TY - CHAP TI - Thermal stability studies of advanced gate stack structures on Si (100) AU - Sivasubramani, P AU - Zhao, P AU - Kim, MJ AU - Gnade, BE AU - Wallace, RM AU - Edge, LF AU - Schlom, DG AU - Parsons, GN AU - Misra, V AU - Seiler, DG AU - Diebold, AC AU - McDonald, R AU - Ayre, CR AU - Khosla, RP AU - Secula, EM T2 - Characterization and Metrology for ULSI Technology 2005 PY - 2005/// VL - 788 SP - 156-160 PB - SE - UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000233588000023&KeyUID=WOS:000233588000023 ER - TY - JOUR TI - Designing interface composition and structure in high dielectric constant gate stacks AU - Parsons, GN AU - Huff, HR AU - Gilmer, DC T2 - High Dielectric Constant Materials DA - 2005/// PY - 2005/// VL - 16 SP - 287-310 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=CCC&KeyUT=CCC:000227551500010&KeyUID=CCC:000227551500010 ER - TY - CONF TI - Present and future challenges in multilayer ceramic devices AU - Randall, CA AU - Yang, G AU - Dickey, E AU - Eitel, RE AU - Shrout, TR AU - Lanagan, MT AU - Kwon, D AU - Semouchkina, E AU - Semouchkin, G AU - Rhee, S AU - Baker, A C2 - 2005/12/1/ C3 - Proceedings - 2005 IMAPS/ACerS 1st International Conference and Exhibition on Ceramic Interconnect and Ceramic Microsystems Technologies, CICMT 2005 DA - 2005/12/1/ SP - 1-8 ER - TY - CONF TI - Electrocatalytic oxidation of methanol on high surface area unsupported catalysts AU - Jambunathan, K AU - Liu, R AU - Pan, L AU - Dickey, E AU - Shallenberger, J AU - Smotkin, E AU - Mallouk, T C2 - 2005/12/13/ C3 - Proceedings - Electrochemical Society DA - 2005/12/13/ VL - PV 2003-30 SP - 108-120 ER - TY - JOUR TI - Evolution of a stable polarization state in lead zirconate titanate ceramics by repeated partial switching AU - Granzow, T. AU - Balke, N. AU - Lupascu, D. C. AU - Rodel, J. T2 - Applied Physics Letters AB - The development of the ferroelectric polarization of lead–zirconate–titanate (PZT) bulk ceramics under varying electric fields is examined. Repeated partial switching and backswitching results in a decrease of the switchable polarization, but has no effect on the effective strain. This is attributed to a stabilization of the domain structure, which leads to a decrease of the electric losses. The results are discussed with respect to the effective strain of PZT ceramics for piezoelectric actuators. DA - 2005/// PY - 2005/// DO - 10.1063/1.2133930 VL - 87 IS - 21 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000233362300058&KeyUID=WOS:000233362300058 ER - TY - JOUR TI - Near electrode fatigue in lead zirconate titanate ceramics AU - Zhang, Y. AU - Lupascu, D. C. AU - Balke, N. AU - Rodel, J. T2 - Journal De Physique Iv AB - Fatigue in ferroelectric materials is partly due to a complex interplay of ferroelectric ceramic and electrode material. Different types of silver electrodes were tested for their effect on fatigue. Material damage mostly occurs in the near-electrode volume. Removal of material to different depths from the electrode yields different degrees of recovery of device properties depending on electrode material and cycle number. Polarization hysteresis, time resolved switching, and small signal dielectric and piezoelectric measurements are equally affected. DA - 2005/// PY - 2005/// DO - 10.1051/jp4:2005128015 VL - 128 SP - 97-103 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000232430400016&KeyUID=WOS:000232430400016 ER - TY - JOUR TI - 2-Chlorobicyclo[2.2.1]hept-5-ene-2-carboxamide and 2-chlorobicyclo[2.2.1]heptane-2-carboxamide as precursors of bicyclo[2.2.1]hept-5-en-2-one and bicyclo[2.2.1]heptan-2-one: resolution, absolute configuration and hydrogen-bonding properties AU - PLETTNER, E AU - MOHLE, A AU - MWANGI, MT AU - GRISCTI, J AU - PATRICK, BO AU - NAIR, R AU - BATCHELOR, RJ AU - EINSTEIN, F T2 - TETRAHEDRON-ASYMMETRY AB - The absolute configuration of bicyclo[2.2.1]heptan-2-one has not been correlated with a crystal structure of a chemical precursor. The only chemical correlation available had an ambiguity, which could have reversed the assignment. Herein, we report the resolution of 2-chlorobicyclo[2.2.1]hept-5-en-2-exo-carboxamide on a cellulose triacetate column and the crystal structures of the enantiomerically pure and racemic α-chloroamide. We found the absolute configuration (1R,2R,4R) for the (+)-enantiomer of the α-chloroamide. This compound was converted to (+)-bicyclo[2.2.1]hept-5-ene-2-one by base hydrolysis, and the 5,6-unsaturated compounds converted to the saturated congeners. This is the first unambiguous experimental determination of the absolute configuration of bicyclo[2.2.1]heptan-2-one and of bicyclo[2.2.1]hept-5-ene-2-one. The three crystal structures of 2-chlorobicyclo[2.2.1]hept-5-en-2-exo-carboxamide reported herein reveal H-bonded dimers, with two distinct orientations of the bicyclic portion relative to the carboxamide dimer. In the racemic crystal, each dimer is composed of two enantiomers, and the bicyclic portions have their bridge carbon atom (C-7) on opposite sides of the H-bonded carboxamide dimer moiety. In the enantiomerically pure crystals, the major dimer had both C-7 atoms on the same side of the carboxamide dimer moiety while the minor dimer had the C-7 atoms on opposite sides. The dimers are present in solution, and can be easily monitored. DA - 2005/// PY - 2005/// DO - 10.1016/j.tetasy.2005.07.016 VL - 16 IS - 16 SP - 2754-2763 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000231719800010&KeyUID=WOS:000231719800010 ER - TY - JOUR TI - Domain texture distributions in tetragonal lead zirconate titanate by x-ray and neutron diffraction AU - Jones, Jacob L. AU - Slamovich, Elliott B. AU - Bowman, Keith J. T2 - Journal of Applied Physics AB - The domain structure of ferroelectric ceramics can be altered by the process of electrical poling. This paper develops quantitative approaches for reflection geometry and spherical harmonic texture analysis, both of which describe these changes at angles parallel to and tilted from the poling axis. The x-ray-diffraction approach uses the relative intensity ratio of ferroelectric poles in poled and unpoled lead zirconate titanate to calculate a domain switching fraction (η) or a multiple of a random distribution, which are shown to be linearly related. An x-ray area detector diffractometer was used for these measurements, although the technique applies to any x-ray reflection geometry. The neutron-diffraction approach employs a Rietveld refinement with a spherical harmonic texture model. Both approaches calculate similar domain textures for two poling fields and the small differences between the approaches can be attributed to surface domain texture. This paper shows that the March–Dollase pole distribution function can inadequately describe domain textures. DA - 2005/2// PY - 2005/2// DO - 10.1063/1.1849821 VL - 97 IS - 3 SP - 034113 J2 - Journal of Applied Physics LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.1849821 DB - Crossref ER - TY - JOUR TI - Saturated domain switching textures and strains in ferroelastic ceramics AU - Jones, Jacob L. AU - Hoffman, Mark AU - Bowman, Keith J. T2 - Journal of Applied Physics AB - This paper introduces saturated domain switching textures of three different ferroelastic ceramic crystal systems. The accompanying extrinsic domain switching strain is calculated exclusively using a volume-weighted integral of a single pole figure. In ceramics which are also ferroelectric, the electromechanical response is defined by the domain switching textures, strains, and strain asymmetry, which are found to be functions of the number and directions of possible ferroelastic structural distortions. DA - 2005/7/15/ PY - 2005/7/15/ DO - 10.1063/1.1988978 VL - 98 IS - 2 SP - 024115 J2 - Journal of Applied Physics LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.1988978 DB - Crossref ER - TY - JOUR TI - Domain switching anisotropy in textured bismuth titanate ceramics AU - Jones, Jacob L. AU - Slamovich, Elliott B. AU - Bowman, Keith J. AU - Lupascu, Doru C. T2 - Journal of Applied Physics AB - In a poled ferroelectric ceramic, the probability of crystallographic poles oriented in any given specimen direction is the multiple of both the initial crystallographic texture and the domain switching fraction. In this paper, the non-180° domain switching fraction is shown to be dependent on the initial crystallographic texture and poling direction in tape cast Na0.5Bi4.5Ti4O15 ceramics. The domain switching fraction is 0.18 out of a maximum of 0.50 when poled in a direction in which most of the possible ferroelastic structural distortions are oriented (tape casting plane) whereas no non-180° domain switching is discernable when poled in a less-preferred direction. The mechanism for domain switching anisotropy in textured bismuth titanate ceramics is suggested to be the synergistic alignment of ferroelastic structural distortions, analogous to the mechanical clamping conditions in poling ferroelastic thin films. DA - 2005/11/15/ PY - 2005/11/15/ DO - 10.1063/1.2128475 VL - 98 IS - 10 SP - 104102 J2 - Journal of Applied Physics LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.2128475 DB - Crossref ER - TY - JOUR TI - Processing of mussel-adhesive protein analog copolymer thin films by matrix-assisted pulsed laser evaporation AU - Patz, T. AU - Cristescu, R. AU - Narayan, R. AU - Menegazzo, N. AU - Mizaikoff, B. AU - Messersmith, P.B. AU - Stamatin, I. AU - Mihailescu, I.N. AU - Chrisey, D.B. T2 - Applied Surface Science AB - We have demonstrated the successful thin film growth of a mussel-adhesive protein analog, DOPA-modified PEO–PPO–PEO block copolymer PF127, using matrix-assisted pulsed laser evaporation (MAPLE). The MAPLE-deposited thin films were examined using Fourier transform infrared spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and contact-angle measurements. We have found that the main functional groups of the mussel-adhesive protein analog are present in the transferred film. These adhesive materials have several potential electronic, medical, and marine applications. DA - 2005/7// PY - 2005/7// DO - 10.1016/j.apsusc.2005.03.056 VL - 248 IS - 1-4 SP - 416-421 J2 - Applied Surface Science LA - en OP - SN - 0169-4332 UR - http://dx.doi.org/10.1016/j.apsusc.2005.03.056 DB - Crossref KW - mussel-adhesive protein KW - matrix-assisted pulsed laser evaporation ER - TY - JOUR TI - Processing of mussel adhesive protein analog thin films by matrix assisted pulsed laser evaporation AU - Cristescu, R. AU - Patz, T. AU - Narayan, R.J. AU - Menegazzo, N. AU - Mizaikoff, B. AU - Mihaiescu, D.E. AU - Messersmith, P.B. AU - Stamatin, I. AU - Mihailescu, I.N. AU - Chrisey, D.B. T2 - Applied Surface Science AB - Mussel adhesive proteins are a new class of biologically-derived materials that possess unique biocompatibility, bioactivity, and adhesion properties. We have demonstrated successful thin film growth of 3,4-dihydroxyphenyl-l-alanine modified poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (DOPA modified- PEO-PPO-PEO) block copolymer, a mussel adhesive protein analog, using matrix assisted pulsed laser evaporation. We have demonstrated that the main functional groups of the mussel adhesive protein analog are present in the transferred film. The effect of increasing of chain length of the mussel adhesive protein analog on film structure was also examined. These novel polymer thin films could have numerous medical and technological applications if their thin film properties are similar to what is found in bulk. This is the first report of successful MAPLE deposition of this material as thin films. DA - 2005/7// PY - 2005/7// DO - 10.1016/j.apsusc.2005.01.066 VL - 247 IS - 1-4 SP - 217-224 J2 - Applied Surface Science LA - en OP - SN - 0169-4332 UR - http://dx.doi.org/10.1016/j.apsusc.2005.01.066 DB - Crossref KW - mussel adhesive protein KW - DOPA-polymer conjugates KW - MAPs analog thin films KW - matrix assisted pulsed laser evaporation ER - TY - JOUR TI - Laser processing of diamond-like carbon–metal composites AU - Narayan, Roger Jagdish T2 - Applied Surface Science AB - Diamond-like carbon (DLC) is a hydrogen-free amorphous material that contains a large fraction of sp3-hybridized carbon atoms. DLC exhibits hardness, corrosion resistance, and wear resistance properties close to those of diamond. Unfortunately, DLC films contain a large amount of compressive stresses and exhibit poor adhesion to many metal substrates. We have adopted a novel pulsed laser deposition process to incorporate metal atoms into diamond-like carbon films. Visible Raman spectroscopy data suggest that DLC–metal composite films possess less internal compressive stress than as-prepared DLC films. DLC–metal composite films have several potential applications, including use in machine tools and medical prostheses. DA - 2005/5// PY - 2005/5// DO - 10.1016/j.apsusc.2004.11.026 VL - 245 IS - 1-4 SP - 420-430 J2 - Applied Surface Science LA - en OP - SN - 0169-4332 UR - http://dx.doi.org/10.1016/j.apsusc.2004.11.026 DB - Crossref KW - pulsed laser deposition KW - diamond-like carbon KW - scanning transmission electron microscopy ER - TY - JOUR TI - Electrical properties of amorphous aluminum oxide thin films AU - Katiyar, P. AU - Jin, C. AU - Narayan, R.J. T2 - Acta Materialia AB - Silicon oxide (SiO2) gate length, gate thickness, junction depth, and source/drain extension scaling have allowed metal–oxide–semiconductor (MOS) gate dimensions to approach the current ⩽100 nm range. High dielectric constant materials for gate insulation and low resistivity junctions must be developed in order to enable further scaling of these devices. Aluminum oxide (Al2O3), with a bandgap of 9.9 eV, is an especially promising material for use as a gate insulator; however, conventional Al2O3 processing techniques suffer from excessive thermal requirements. We have grown α-Al2O3 thin films directly on silicon (1 0 0) at room temperature using pulsed laser deposition (PLD). Atomic-resolution transmission electron microscopy, Z-contrast scanning transmission electron microscopy, capacitance–voltage measurements, and current–voltage measurements were used to determine the nanoscale features and electrical properties of amorphous Al2O3 thin films. Our results suggest that amorphous Al2O3 films prepared using pulsed laser deposition may serve as high dielectric constant materials for next generation electronic devices. DA - 2005/5// PY - 2005/5// DO - 10.1016/j.actamat.2005.02.027 VL - 53 IS - 9 SP - 2617-2622 J2 - Acta Materialia LA - en OP - SN - 1359-6454 UR - http://dx.doi.org/10.1016/j.actamat.2005.02.027 DB - Crossref KW - aluminum oxide KW - pulsed laser deposition KW - thin films KW - high dielectric constant materials ER - TY - JOUR TI - Laser Processing of Advanced Bioceramics AU - Narayan, R. J. AU - Jin, C. AU - Doraiswamy, A. AU - Mihailescu, I. N. AU - Jelinek, M. AU - Ovsianikov, A. AU - Chichkov, B. AU - Chrisey, D. B. T2 - Advanced Engineering Materials AB - Abstract In this article, laser processing of diamondlike carbon‐metal nanocomposite films, hydroxyapatite‐osteoblast composites, and Ormocer® microdevices for medical applications is described. Pulsed laser deposition has been used to process diamondlike carbon‐silver‐platinum nanocomposite films that provide hardness, wear resistance, corrosion resistance, and antimicrobial functionalities to cardiovascular, orthopaedic, biosensor, and MEMS devices. Laser direct writing has been used for fabricating integrated cell‐scaffold structures. Two photon induced polymerization has been used to create Ormocer® tissue engineering scaffolds and microneedles with unique geometries. Pulsed laser deposition, laser direct write, and two photon induced polymerization techniques may provide medical engineers with advanced biomaterials that possess unique structures and functionalities. DA - 2005/12// PY - 2005/12// DO - 10.1002/adem.200500155 VL - 7 IS - 12 SP - 1083-1098 J2 - Adv. Eng. Mater. LA - en OP - SN - 1438-1656 1527-2648 UR - http://dx.doi.org/10.1002/adem.200500155 DB - Crossref ER - TY - JOUR TI - Nanostructured diamondlike carbon thin films for medical applications AU - Narayan, Roger J. T2 - Materials Science and Engineering: C AB - Diamondlike carbon (DLC) is an amorphous form of carbon that may contain a high fraction of sp3-hybridized carbon atoms. DLC thin films possess high hardness values, low coefficient of friction values, chemical inertness, and compatibility with human cells. The cardiovascular, orthopedic, ophthalmic, biosensor, and microelectromechanical system (MEMS) device applications for diamondlike carbon thin films are reviewed. Finally, processing of nanostructured diamondlike carbon thin films for medical applications is presented. DA - 2005/5// PY - 2005/5// DO - 10.1016/j.msec.2005.01.026 VL - 25 IS - 3 SP - 405-416 J2 - Materials Science and Engineering: C LA - en OP - SN - 0928-4931 UR - http://dx.doi.org/10.1016/j.msec.2005.01.026 DB - Crossref KW - pulsed laser deposition KW - diamondlike carbon KW - bioactive ceramics KW - antimicrobial properties ER - TY - JOUR TI - Hydroxyapatite–diamondlike carbon nanocomposite films AU - Narayan, Roger J. T2 - Materials Science and Engineering: C AB - Hydroxyapatite is a bioactive ceramic that mimics the mineral composition of natural bone. Conventional plasma-sprayed hydroxyapatite coatings demonstrate poor adhesion and poor mechanical integrity. We have developed hydroxyapatite–diamondlike carbon bilayer film. The diamondlike carbon interlayer serves to prevent metal ion release and improve adhesion of the hydroxyapatite film. These films were characterized using X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, nanoindentation, and microscratch adhesion testing. Based on the results of this study, hydroxyapatite–diamondlike carbon bilayers demonstrate promise for use in several orthopedic implants. DA - 2005/5// PY - 2005/5// DO - 10.1016/j.msec.2005.01.023 VL - 25 IS - 3 SP - 398-404 J2 - Materials Science and Engineering: C LA - en OP - SN - 0928-4931 UR - http://dx.doi.org/10.1016/j.msec.2005.01.023 DB - Crossref ER - TY - JOUR TI - Two-dimensional differential adherence and alignment of C2C12 myoblasts AU - Patz, T.M. AU - Doraiswamy, A. AU - Narayan, R.J. AU - Modi, R. AU - Chrisey, D.B. T2 - Materials Science and Engineering: B AB - Surface microstructure is a critical parameter for scaffolds used in skeletal muscle tissue engineering. We have developed micromachined surfaces using matrix assisted pulsed laser evaporation-direct write (MAPLE-DW) that demonstrate differential adherence of C2C12 myoblast cells. The 60–400 μm diameter channels were micromachined onto 2% agarose surfaces using an ArF excimer laser and lined with Matrigel® basement membrane matrix solution. Suspensions containing C2C12 myoblast cells were then placed on the surface of these micromachined channels. The C2C12 myoblast cells aligned themselves parallel to the 60–150 μm channels. Live/dead assays over 72 h demonstrated that cell number, cell size, and number of nuclei per cell increased within these channels. In addition, some of the myoblasts fused and differentiated into multinucleated myotubes. These results provide the basis for the development of direct-write scaffolds for skeletal muscle tissue engineering. DA - 2005/11// PY - 2005/11// DO - 10.1016/j.mseb.2005.08.088 VL - 123 IS - 3 SP - 242-247 J2 - Materials Science and Engineering: B LA - en OP - SN - 0921-5107 UR - http://dx.doi.org/10.1016/j.mseb.2005.08.088 DB - Crossref KW - laser processing KW - matrix assisted pulsed laser evaporation-direct write KW - biomaterials ER - TY - JOUR TI - Structural and biological properties of carbon nanotube composite films AU - Narayan, Roger J. AU - Berry, C.J. AU - Brigmon, R.L. T2 - Materials Science and Engineering: B AB - Carbon nanotube composite films have been developed that exhibit unusual structural and biological properties. These novel materials have been created by pulsed laser ablation of graphite and bombardment of nitrogen ions at temperatures between 600 and 700 °C. High-resolution transmission electron microscopy and radial distribution function analysis demonstrate that this material consists of sp2-bonded concentric ribbons that are wrapped approximately 15° normal to the silicon substrate. The interlayer order in this material extends to approximately 15–30 Å. X-ray photoelectron spectroscopy and Raman spectroscopy data suggest that this material is predominantly trigonally coordinated. The carbon nanotube composite structure results from the use of energetic ions, which allow for non-equilibrium growth of graphitic planes. In vitro testing has revealed significant antimicrobial activity of carbon nanotube composite films against Staphylococcus aureus and Staphylococcus warneri colonization. Carbon nanotube composite films may be useful for inhibiting microorganism attachment and biofilm formation in hemodialysis catheters and other medical devices. DA - 2005/11// PY - 2005/11// DO - 10.1016/j.mseb.2005.07.007 VL - 123 IS - 2 SP - 123-129 J2 - Materials Science and Engineering: B LA - en OP - SN - 0921-5107 UR - http://dx.doi.org/10.1016/j.mseb.2005.07.007 DB - Crossref KW - pulsed laser deposition KW - Kaufman ion source KW - antimicrobial materials ER - TY - JOUR TI - Pulsed laser deposition of functionally gradient diamondlike carbon–metal nanocomposites AU - Narayan, Roger Jagdish T2 - Diamond and Related Materials AB - Diamondlike carbon thin films possess atomic smoothness, chemical inertness, and hardness properties close to those of diamond. Unfortunately, these films exhibit poor adhesion to metals and polymers used in medical prostheses. This paper presents the processing and characterization of diamondlike carbon–copper, diamondlike carbon–silver, diamondlike carbon–silicon, and diamondlike carbon–titanium nanocomposite films with enhanced adhesion to Ti–6Al–4V alloy substrates. Silver forms nanoparticle arrays within the diamondlike carbon matrix in diamondlike carbon–silver nanocomposite films. On the other hand, titanium forms layers of titanium carbide within the diamondlike carbon matrix in diamondlike carbon–titanium nanocomposite films. These films were characterized using electron energy loss spectroscopy, transmission electron microscopy, Raman spectroscopy, Rutherford backscattering spectrometry, nanoindentation, wear testing, and scratch adhesion testing. Diamondlike carbon–metal nanocomposite films have numerous potential medical applications, including use on the surfaces of medical prostheses. DA - 2005/8// PY - 2005/8// DO - 10.1016/j.diamond.2004.12.047 VL - 14 IS - 8 SP - 1319-1330 J2 - Diamond and Related Materials LA - en OP - SN - 0925-9635 UR - http://dx.doi.org/10.1016/j.diamond.2004.12.047 DB - Crossref KW - pulse laser deposition KW - diamondlike carbon KW - nanoindentation ER - TY - JOUR TI - Dry-sliding tribological properties of ultrafine-grained Ti prepared by severe plastic deformation AU - La, PeiQing AU - Ma, JiQiang AU - Zhu, Yuntian T. AU - Yang, Jun AU - Liu, WeiMin AU - Xue, QunJi AU - Valiev, Ruslan Z. T2 - Acta Materialia AB - This paper reports the tribological properties of ultrafine-grained (UFG) Ti prepared by severe plastic deformation under dry sliding against AISI52100 steel in ambient environment and at varying load and sliding speed. Worn surfaces of the UFG Ti were examined with a scanning electron microscope and X-ray photoelectron spectroscope. It was found that the wear rate of the UFG Ti under dry sliding was of the magnitude of 10−3 mm3 m−1, which is lower than that of the annealed coarse-grained (CG) Ti. The wear rate of the UFG Ti increased with the load, while it decreased with the sliding speed. The friction coefficient of the UFG Ti was in the range of 0.45–0.60, slightly lower than that of the CG Ti, and did not change with the load and sliding time after the initial transient period. The friction coefficient increased with increasing sliding speed to a maximum point and then decreased. The wear mechanism of the UFG Ti was micro-ploughing and delamination. The worn surfaces were covered by a TiO2 layer. These results demonstrated that UFG structures improved the wear resistance but did not significantly affect the friction coefficient of Ti. DA - 2005/11// PY - 2005/11// DO - 10.1016/j.actamat.2005.07.031 VL - 53 IS - 19 SP - 5167-5173 J2 - Acta Materialia LA - en OP - SN - 1359-6454 UR - http://dx.doi.org/10.1016/j.actamat.2005.07.031 DB - Crossref KW - ultrafine-grained Ti KW - friction and wear behavior KW - wear mechanism ER - TY - BOOK TI - Book Review: Plastic Deformation in Nanocrystalline Materials. By M. Yu. Gutkin and I. A. Ovid'ko. AU - Zhu, Yuntian T. AU - Gutkin, M. Yu. AU - Ovid'ko, I.A. AB - Advanced MaterialsVolume 17, Issue 20 p. 2513-2514 Book Review Book Review: Plastic Deformation in Nanocrystalline Materials. By M. Yu. Gutkin and I. A. Ovid'ko. Yuntian T. Zhu, Search for more papers by this author Yuntian T. Zhu, Search for more papers by this author First published: 07 October 2005 https://doi.org/10.1002/adma.200590101Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume17, Issue20October, 2005Pages 2513-2514 RelatedInformation DA - 2005/10/17/ PY - 2005/10/17/ DO - 10.1002/adma.200590101 VL - 17 PB - Wiley SE - 2513–2514 UR - http://dx.doi.org/10.1002/adma.200590101 ER - TY - JOUR TI - Nucleation of deformation twins in nanocrystalline face-centered-cubic metals processed by severe plastic deformation AU - Zhu, Y. T. AU - Liao, X. Z. AU - Srinivasan, S. G. AU - Lavernia, E. J. T2 - Journal of Applied Physics AB - Nanocrystalline (nc) materials are known to deform via mechanisms not accessible to their coarse-grained counterparts. For example, deformation twins and partial dislocations emitted from grain boundaries have been observed in nc Al and Cu synthesized by severe plastic deformation (SPD). This paper further develops an earlier dislocation-based model on the nucleation of deformation twins in nc face-centered-cubic (fcc) metals. It is found that there exists an optimum grain-size range in which deformation twins nucleate most readily. The critical twinning stress is found determined primarily by the stacking fault energy while the optimum grain size is largely determined by ratio of shear modulus to stacking fault energy. This model formulated herein is applicable to fcc nanomaterials synthesized by SPD techniques and provide a lower bound to the critical twining stress. DA - 2005/8// PY - 2005/8// DO - 10.1063/1.2006974 VL - 98 IS - 3 SP - 034319 J2 - Journal of Applied Physics LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.2006974 DB - Crossref ER - TY - JOUR TI - Formation mechanism of fivefold deformation twins in nanocrystalline face-centered-cubic metals AU - Zhu, Y. T. AU - Liao, X. Z. AU - Valiev, R. Z. T2 - Applied Physics Letters AB - Fivefold deformation twins have been recently observed in nanocrystalline face-centered-cubic (fcc) metals and alloys synthesized by severe plastic deformation techniques. However, numerous molecular dynamics simulations in the literature have not observed fivefold deformation twins in nanocrystalline fcc metals. The discrepancy between experimental observations and molecular dynamics simulations has raised an issue on their formation mechanism and conditions. Here we propose a sequential twinning mechanism that provides a clear path for the formation of fivefold deformation twins. The mechanism requires an orientation change of applied stresses, which explains why molecular dynamics simulations under a constant load orientation do not produce fivefold deformation twins. DA - 2005/3/7/ PY - 2005/3/7/ DO - 10.1063/1.1879111 VL - 86 IS - 10 SP - 103112 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.1879111 DB - Crossref ER - TY - JOUR TI - Disordered Phases in Magnetoresistance Sr2FeMoO6 Induced by Cation Deficiency AU - Liao, X Z AU - MacManus-Driscoll, J L AU - Zhu, Y T AU - Peterson, D E AU - Xu, H F T2 - Microscopy and Microanalysis AB - Extract HTML view is not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button. Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005 DA - 2005/8// PY - 2005/8// DO - 10.1017/S1431927605503593 VL - 11 IS - S02 J2 - MAM LA - en OP - SN - 1431-9276 1435-8115 UR - http://dx.doi.org/10.1017/S1431927605503593 DB - Crossref ER - TY - JOUR TI - The Langdon Symposium: Flow and Forming of Crystalline Materials AU - Zhu, Yuntian T. AU - Horita, Zenji AU - Xia, Kenong AU - Berbon, Patrick B. AU - Raj, Sai V. AU - Chokshi, Atul H. AU - Kostorz, Gernot T2 - Materials Science and Engineering: A DA - 2005/11// PY - 2005/11// DO - 10.1016/j.msea.2005.08.106 VL - 410-411 SP - 1-2 J2 - Materials Science and Engineering: A LA - en OP - SN - 0921-5093 UR - http://dx.doi.org/10.1016/j.msea.2005.08.106 DB - Crossref ER - TY - JOUR TI - Contribution of early works by Terence G. Langdon to modern materials science AU - Valiev, Ruslan Z. AU - Zhu, Yuntian T. T2 - Materials Science and Engineering: A AB - Professor Terence G. Langdon has been ranked as the second most cited author in materials science of the last 10 years by the international Institute for Scientific Information (Philadelphia, PA, USA). An analysis of his works shows that his most highly cited publications are those dealing with recent studies of microstructural evolution and mechanical properties of ultrafine-grained (UFG) materials processed by severe plastic deformation, as well as earlier papers on creep and superplasticity carried out in the 1970–1980s. This paper overviews the landmarks in the research activity of Prof. Langdon, and traces how his early works have affected the current investigations of the mechanical behavior of UFG materials produced by severe plastic deformation. DA - 2005/11// PY - 2005/11// DO - 10.1016/j.msea.2005.08.105 VL - 410-411 SP - 5-7 J2 - Materials Science and Engineering: A LA - en OP - SN - 0921-5093 UR - http://dx.doi.org/10.1016/j.msea.2005.08.105 DB - Crossref KW - creep KW - superplasticity KW - ultrafine grains KW - severe plastic deformation ER - TY - JOUR TI - Nanostructured TiNi-based shape memory alloys processed by severe plastic deformation AU - Pushin, V.G. AU - Stolyarov, V.V. AU - Valiev, R.Z. AU - Lowe, T.C. AU - Zhu, Y.T. T2 - Materials Science and Engineering: A AB - We present the processing, microstructure and properties of nanostructured TiNi-based shape-memory alloys synthesized by severe plastic deformation (SPD), including high-pressure torsion, equal-channel angular pressing, and multi-step SPD deformation (SPD plus cold rolling or drawing). It was found that the SPD processing did not alter the phase transformation sequence of the alloys but changed the morphology of the martensite. Also, we found that the mechanical and shape memory properties were improved by forming nanostructures in these alloys; SPD processing rendered a higher recovery stress (up to 1.5 GPa) and a higher maximum reverse strain (up to 10%) of shape memory, which are desirable in various practical applications. DA - 2005/11// PY - 2005/11// DO - 10.1016/j.msea.2005.08.071 VL - 410-411 SP - 386-389 J2 - Materials Science and Engineering: A LA - en OP - SN - 0921-5093 UR - http://dx.doi.org/10.1016/j.msea.2005.08.071 DB - Crossref KW - TiNi-based alloys KW - severe plastic deformation KW - nanostructure KW - martensitic transformation KW - shape memory KW - physical properties ER - TY - JOUR TI - Formation mechanisms of nanostructures in stainless steel during high-strain-rate severe plastic deformation AU - Xue, Q. AU - Liao, X.Z. AU - Zhu, Y.T. AU - Gray, G.T., III T2 - Materials Science and Engineering: A AB - We have investigated the formation mechanisms of nanostructures within adiabatic shear bands formed in stainless steel samples deformed by high-strain-rate forced shear. Twinning is shown to play a critical role in the initiation of nanostructures. Secondary twins directly led to the formation of elongated subgrains. Microtwins inside shear bands promoted division and break-down of the subgrains, which further refined the microstructures. DA - 2005/11// PY - 2005/11// DO - 10.1016/j.msea.2005.08.022 VL - 410-411 SP - 252-256 J2 - Materials Science and Engineering: A LA - en OP - SN - 0921-5093 UR - http://dx.doi.org/10.1016/j.msea.2005.08.022 DB - Crossref KW - nanostructure KW - grain refinement KW - adiabatic shear localization KW - stainless steel ER - TY - JOUR TI - New frontiers in thin film growth and nanomaterials AU - Narayan, Jagdish T2 - Metallurgical and Materials Transactions B DA - 2005/2// PY - 2005/2// DO - 10.1007/s11663-005-0001-8 VL - 36 IS - 1 SP - 5-22 J2 - Metall and Materi Trans B LA - en OP - SN - 1073-5615 1543-1916 UR - http://dx.doi.org/10.1007/s11663-005-0001-8 DB - Crossref ER - TY - JOUR TI - The effect of interfacial layer on the performance of organic light-emitting diodes AU - Choulis, Stelios A. AU - Choong, Vi-En AU - Mathai, Mathew K. AU - So, Franky T2 - Applied Physics Letters AB - We demonstrate high efficiency organic light-emitting devices by incorporation of a nanoscale interfacial layer between a hole-conducting layer (PEDOT:PSS) and a light-emitting polymer layer (LEP) to improve hole injection. The interfacial layer has appropriate highest occupied molecular orbital level in order to act as a bridge for efficient hole injection from the PEDOT:PSS into the LEP. As an example we have incorporated a suitable interfacial layer into a green-emitting single-layer electrophosphorescent light-emitting diode. Devices with the interfacial layer show a peak efficiency of 41lm∕W, an improvement of more than 25% in their performance over comparable devices without the interfacial layer. The results presented here introduce a novel method to improve hole injection and thus efficiency in organic electroluminescent devices. DA - 2005/9/12/ PY - 2005/9/12/ DO - 10.1063/1.2042635 VL - 87 IS - 11 SP - 113503 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.2042635 DB - Crossref ER - TY - JOUR TI - Bipolar charge transport, injection, and trapping studies in a model green-emitting polyfluorene copolymer AU - Poplavskyy, Dmitry AU - Su, Wencheng AU - So, Franky T2 - Journal of Applied Physics AB - Experimental studies of charge injection and transport of holes and electrons in LUMATION™ Green 1300 Series light-emitting polymer (LEP) by a combination of experimental techniques are reported. It is found that hole mobility is lower than electron mobility and the former exhibits steeper electric-field dependence thus reducing the misbalance between charge mobilities at higher device operating voltages. An approach to quantitatively analyze charge injection and trapping in organic semiconductors is proposed. Based on our analysis, hole current is limited by injection from the anode and trapping in the bulk of the polymer. Further, we found that hole trapping is approximately independent of electric field and injection efficiency increases with increasing electric field. Injection limitation of holes from poly(3,4-ethylenedioxythiophene)/polystyrenesulphonic acid (PEDOT:PSS) electrode is believed to be the result of nonuniform contact between the PEDOT:PSS and LEP rather than the energy barrier. On the other hand, electron injection is close to ohmic and the steady-state electron current is affected by trapping, mainly due to deep traps prevailing at low electric fields and with an estimated concentration of 1016cm−3. Electron trapping is found to be significantly reduced in dual-carrier devices, which is believed to be the effect of faster exciton formation and recombination rates, compared to electron trapping processes. DA - 2005/7// PY - 2005/7// DO - 10.1063/1.1941482 VL - 98 IS - 1 SP - 014501 J2 - Journal of Applied Physics LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.1941482 DB - Crossref ER - TY - JOUR TI - Phosphine Oxide Polymer for Water-Soluble Nanoparticles AU - Kim, Sang-Wook AU - Kim, Sungjee AU - Tracy, Joseph B. AU - Jasanoff, Alan AU - Bawendi, Moungi G. T2 - Journal of the American Chemical Society AB - A phosphine oxide polymer was developed using bis(dichlorophosphino)ethane and poly(ethylene glycol). This polymer system was used to transfer various nanoparticles from organic solvents to water, retaining their physical properties and reactivities. DA - 2005/4// PY - 2005/4// DO - 10.1021/ja043577f VL - 127 IS - 13 SP - 4556-4557 J2 - J. Am. Chem. Soc. LA - en OP - SN - 0002-7863 1520-5126 UR - http://dx.doi.org/10.1021/ja043577f DB - Crossref ER - TY - JOUR TI - Epitaxial growth and properties of Zn1−xVxO diluted magnetic semiconductor thin films AU - Ramachandran, S. AU - Tiwari, A. AU - Narayan, J. AU - Prater, J. T. T2 - Applied Physics Letters AB - Here we report systematic studies on the epitaxial growth and properties of Zn1−xVxO[x=0.001-0.2] thin films deposited onto sapphire c-plane single crystals. The thin films were deposited using pulsed laser deposition technique and were found to be epitaxial in nature. X-ray diffraction and high resolution transmission electron microscopy were employed to study the epitaxial relations of Zn1−xVxO with the sapphire substrate and electron energy loss spectroscopy was used to establish the bonding characteristics and oxidation states of vanadium inside the ZnO host. The main emphasis is on the magnetic properties of this system taking into consideration the phase purity and microstructural characteristics of these films. Our results show that the Zn1−xVxO system, with V in zinc substitutional sites, does not exhibit any signature of ferromagnetism, both at room temperature as well as at lower temperatures down to 10 K. DA - 2005/10/24/ PY - 2005/10/24/ DO - 10.1063/1.2112185 VL - 87 IS - 17 SP - 172502 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.2112185 DB - Crossref ER - TY - JOUR TI - Publisher's Note: “Electrical transport in ZnO1−δfilms: Transition from band-gap insulator to Anderson localized insulator” [J. Appl. Phys. 96, 3827 (2004)] AU - Tiwari, Ashutosh AU - Jin, C. AU - Narayan, J. AU - Park, M. T2 - Journal of Applied Physics DA - 2005/3// PY - 2005/3// DO - 10.1063/1.1861992 VL - 97 IS - 5 SP - 059902 J2 - Journal of Applied Physics LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.1861992 DB - Crossref ER - TY - JOUR TI - Transmission Electron Microtomography (TEMT) of Nanostructured Polymers and Polymer Nanocomposites AU - Spontak, R J AU - Gozen, A O AU - Braunfeld, M B AU - Agard, D A T2 - Microscopy and Microanalysis AB - Extract HTML view is not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button. Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005 DA - 2005/8// PY - 2005/8// DO - 10.1017/S1431927605510341 VL - 11 IS - S02 J2 - MAM LA - en OP - SN - 1431-9276 1435-8115 UR - http://dx.doi.org/10.1017/S1431927605510341 DB - Crossref ER - TY - JOUR TI - DNA-programmed assembly of nanostructures AU - Gothelf, Kurt V. AU - LaBean, Thomas H. T2 - Organic & Biomolecular Chemistry AB - DNA is a unique material for nanotechnology since it is possible to use base sequences to encode instructions for assembly in a predetermined fashion at the nanometre scale. Synthetic oligonucleotides are readily obtained by automated synthesis and numerous techniques have been developed for conjugating DNA with other materials. The exact spatial positioning of materials is crucial for the future development of complex nanodevices and the emerging field of DNA-nanotechnology is now exploring DNA-programmed processes for the assembly of organic compounds, biomolecules, and inorganic materials. DA - 2005/// PY - 2005/// DO - 10.1039/b510551j VL - 3 IS - 22 SP - 4023 J2 - Org. Biomol. Chem. LA - en OP - SN - 1477-0520 1477-0539 UR - http://dx.doi.org/10.1039/b510551j DB - Crossref ER - TY - JOUR TI - Programmable DNA Self-Assemblies for Nanoscale Organization of Ligands and Proteins AU - Park, Sung Ha AU - Yin, Peng AU - Liu, Yan AU - Reif, John H. AU - LaBean, Thomas H. AU - Yan, Hao T2 - Nano Letters AB - We demonstrate the precise control of periodic spacing between individual protein molecules by programming the self-assembly of DNA tile templates. In particular, we report the application of two self-assembled periodic DNA structures, two-dimendional nanogrids, and one-dimensional nanotrack, as template for programmable self-assembly of streptavidin protein arrays with controlled density. DA - 2005/4// PY - 2005/4// DO - 10.1021/nl050175c VL - 5 IS - 4 SP - 729-733 J2 - Nano Lett. LA - en OP - SN - 1530-6984 1530-6992 UR - http://dx.doi.org/10.1021/nl050175c DB - Crossref ER - TY - JOUR TI - Three-Helix Bundle DNA Tiles Self-Assemble into 2D Lattice or 1D Templates for Silver Nanowires AU - Park, Sung Ha AU - Barish, Robert AU - Li, Hanying AU - Reif, John H. AU - Finkelstein, Gleb AU - Yan, Hao AU - LaBean, Thomas H. T2 - Nano Letters AB - We present a DNA nanostructure, the three-helix bundle (3HB), which consists of three double helical DNA domains connected by six immobile crossover junctions such that the helix axes are not coplanar. The 3HB motif presents a triangular cross-section with one helix lying in the groove formed by the other two. By differential programming of sticky-ends, 3HB tiles can be arrayed in two distinct lattice conformations: one-dimensional filaments and two-dimensional lattices. Filaments and lattices have been visualized by high-resolution, tapping mode atomic force microscopy (AFM) under buffer. Their dimensions are shown to be in excellent agreement with designed structures. We also demonstrate an electroless chemical deposition for fabricating metallic nanowires templated on self-assembled filaments. The metallized nanowires have diameters down to 20 nm and display Ohmic current-voltage characteristic. DA - 2005/4// PY - 2005/4// DO - 10.1021/nl050108i VL - 5 IS - 4 SP - 693-696 J2 - Nano Lett. LA - en OP - SN - 1530-6984 1530-6992 UR - http://dx.doi.org/10.1021/nl050108i DB - Crossref ER - TY - CHAP TI - Design, Simulation, and Experimental Demonstration of Self-assembled DNA Nanostructures and Motors AU - Reif, John H. AU - LaBean, Thomas H. AU - Sahu, Sudheer AU - Yan, Hao AU - Yin, Peng T2 - Lecture Notes in Computer Science AB - Self-assembly is the spontaneous self-ordering of substructures into superstructures, driven by the selective affinity of the substructures. Complementarity of DNA bases renders DNA an ideal material for programmable self-assembly of nanostructures. DNA self-assembly is the most advanced and versatile system that has been experimentally demonstrated for programmable construction of patterned systems on the molecular scale. The methodology of DNA self-assembly begins with the synthesis of single strand DNA molecules that self-assemble into macromolecular building blocks called DNA tiles. These tiles have single strand “sticky ends” that complement the sticky ends of other DNA tiles, facilitating further assembly into larger structures known as DNA tiling lattices. In principle, DNA tiling assemblies can form any computable two or three-dimensional pattern, however complex, with the appropriate choice of the tiles’ component DNA. Two-dimensional DNA tiling lattices composed of hundreds of thousands of tiles have been demonstrated experimentally. These assemblies can be used as programmable scaffolding to position molecular electronics and robotics components with precision and specificity, facilitating fabrication of complex nanoscale devices. We overview the evolution of DNA self-assembly techniques from pure theory, through simulation and design, and then to experimental practice. In particular, we begin with an overview of theoretical models and algorithms for DNA lattice self-assembly. Then we describe our software for the simulation and design of DNA tiling assemblies and DNA nano-mechanical devices. As an example, we discuss models, algorithms, and computer simulations for the key problem of error control in DNA lattice self-assembly. We then briefly discuss our laboratory demonstrations of DNA lattices and motors, including those using the designs aided by our software. These experimental demonstrations of DNA self-assemblies include the assembly of patterned objects at the molecular scale, the execution of molecular computations, and the autonomous DNA walking and computing devices. PY - 2005/// DO - 10.1007/11527800_14 SP - 173-187 OP - PB - Springer Berlin Heidelberg SN - 9783540278849 9783540314820 UR - http://dx.doi.org/10.1007/11527800_14 DB - Crossref ER - TY - JOUR TI - Magnetic wires with DNA cores: A magnetic force microscopy study AU - Nyamjav, Dorjderem AU - Kinsella, Joseph M. AU - Ivanisevic, Albena T2 - Applied Physics Letters AB - Magnetic force microscopy (MFM) has been employed to study Fe3O4 nanowires containing DNA cores. The MFM experiments confirmed that long DNA molecules templated with Fe3O4 nanoparticles form a magnetic wire. The components of wires containing particles with sizes below 10 nm were recorded to behave as single domain particles with out-of-plane magnetization. The MFM study showed that one can change the magnetization states of the particles using a magnetic tip. The properties of the magnetic wires with DNA cores make them an attractive material for future magnetostatic devices. DA - 2005/2/28/ PY - 2005/2/28/ DO - 10.1063/1.1875748 VL - 86 IS - 9 SP - 093107 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.1875748 DB - Crossref ER - TY - JOUR TI - Fabrication of positively and negatively charged polyelectrolyte structures by dip-pen nanolithography AU - Yu, Meng AU - Nyamjav, Dorjderem AU - Ivanisevic, Albena T2 - Journal of Materials Chemistry AB - Dip-Pen Nanolithography (DPN) is successfully used to pattern two polyelectrolytes: poly(diallyldimethylammonium) chloride, PDDA and poly(styrenesulfonate), PSS, on two types of surfaces: clean SiOx and SiOx coated with a layer of PDDA. Lateral Force Microscopy, Force Volume Imaging and X-ray Photoelectron Spectroscopy were used to verify the chemical composition of the patterns. DA - 2005/// PY - 2005/// DO - 10.1039/b409406a VL - 15 IS - 6 SP - 649 J2 - J. Mater. Chem. LA - en OP - SN - 0959-9428 1364-5501 UR - http://dx.doi.org/10.1039/b409406a DB - Crossref ER - TY - JOUR TI - Study of the Morphological and Adhesion Properties of Collagen Fibers in the Bruch's Membrane AU - Mallick, Shrestha Basu AU - Ivanisevic, Albena T2 - The Journal of Physical Chemistry B AB - The Bruch's membrane is located beneath the retina in vertebrate eyes. We have used atomic force microscopy to examine the morphological and adhesion properties of collagen fibers located in different portions of the membrane. The D-periodicity of the fibers was 62.54 +/- 4.25 nm and 63.78 +/- 4.14 nm for regions away from the optic nerve and close to it, respectively. The adhesion properties of the collagen fibers were evaluated using force volume imaging on a number of different eye samples. The adhesion force we recorded in regions away from the optic nerve was different compared to regions close to the optic nerve. The reported results allow us to understand the nanoscopic properties of connective tissues in the eye and are important for the design of new and improved biomaterials. DA - 2005/10// PY - 2005/10// DO - 10.1021/jp053605w VL - 109 IS - 41 SP - 19052-19055 J2 - J. Phys. Chem. B LA - en OP - SN - 1520-6106 1520-5207 UR - http://dx.doi.org/10.1021/jp053605w DB - Crossref ER - TY - JOUR TI - Covalent Attachment of TAT Peptides and Thiolated Alkyl Molecules on GaAs Surfaces AU - Cho, Youngnam AU - Ivanisevic, Albena T2 - The Journal of Physical Chemistry B AB - Four TAT peptide fragments were used to functionalize GaAs surfaces by adsorption from solution. In addition, two well-studied alkylthiols, mercaptohexadecanoic acid (MHA) and 1-octadecanethiol (ODT) were utilized as references to understand the structure of the TAT peptide monolayer on GaAs. The different sequences of TAT peptides were employed in recognition experiments where a synthetic RNA sequence was tested to verify the specific interaction with the TAT peptide. The modified GaAs surfaces were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS). AFM studies were used to compare the surface roughness before and after functionalization. XPS allowed us to characterize the chemical composition of the GaAs surface and conclude that the monolayers composed of different sequences of peptides have similar surface chemistries. Finally, FT-IRRAS experiments enabled us to deduce that the TAT peptide monolayers have a fairly ordered and densely packed alkyl chain structure. The recognition experiments showed preferred interaction of the RNA sequence toward peptides with high arginine content. DA - 2005/7// PY - 2005/7// DO - 10.1021/jp0515737 VL - 109 IS - 26 SP - 12731-12737 J2 - J. Phys. Chem. B LA - en OP - SN - 1520-6106 1520-5207 UR - http://dx.doi.org/10.1021/jp0515737 DB - Crossref ER - TY - JOUR TI - TAT Peptide Immobilization on Gold Surfaces:  A Comparison Study with a Thiolated Peptide and Alkylthiols Using AFM, XPS, and FT-IRRAS AU - Cho, Youngnam AU - Ivanisevic, Albena T2 - The Journal of Physical Chemistry B AB - A TAT peptide was used to functionalize a gold surface by three different methods: adsorption from solution, microcontact printing, and dip-pen nanolithography (DPN). The composition and structure of the modified gold was characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Fourier transform -infrared reflection absorption spectroscopy (FT-IRRAS). We used two well-studied alkylthiols, mercaptohexadecanoic acid and 1-octadecanethiol, as a comparison in order to understand the structure of the TAT peptide monolayers prepared by the three methods. AFM studies allowed us to assess the homogeneity after each modification protocol. XPS was used to characterize the chemical composition of the gold surface after each functionalization procedure. The XPS results showed that surfaces modified with the TAT peptide by the three methods exhibit similar surface chemistry. Finally, FT-IRRAS experiments allowed us to conclude that the structure of the alkyl chains of the TAT peptides is fairly disordered and different after each procedure. Regardless of the type of surface functionalization method used, the monolayer of TAT peptide formed on the surface was of "liquidlike" nature. DA - 2005/4// PY - 2005/4// DO - 10.1021/jp045731q VL - 109 IS - 13 SP - 6225-6232 J2 - J. Phys. Chem. B LA - en OP - SN - 1520-6106 1520-5207 UR - http://dx.doi.org/10.1021/jp045731q DB - Crossref ER - TY - JOUR TI - Enzymatic Clipping of DNA Wires Coated with Magnetic Nanoparticles AU - Kinsella, Joseph M. AU - Ivanisevic, Albena T2 - Journal of the American Chemical Society AB - The study describes how DNA coated with magnetic nanoparticles remains biologically active and accessible to the BamH1 restriction enzyme. Long DNA molecules are coated with magnetic nanoparticles using electrostatic interactions. The coated, stretched, and surface-bound DNA is incubated in the restriction enzyme that specifically recognizes any strand containing the GGATCC base sequence and clips the DNA. We show that, despite the presence of the nanoparticles on the DNA, the enzyme is still able to recognize the cleavage site and effectively digest the assembly. DA - 2005/3// PY - 2005/3// DO - 10.1021/ja043865b VL - 127 IS - 10 SP - 3276-3277 J2 - J. Am. Chem. Soc. LA - en OP - SN - 0002-7863 1520-5126 UR - http://dx.doi.org/10.1021/ja043865b DB - Crossref ER - TY - JOUR TI - Structural and adhesion properties of surfaces functionalized with polyelectrolytes and polystyrene particles AU - Nyamjav, D AU - Ivanisevic, A T2 - Talanta AB - Surfaces functionalized with polystyrene particles and polyelectrolytes were used to investigate the morphological and adhesion properties of composite substrates. Atomic force microscopy (AFM) studies showed that surfaces with non-homogeneous topography have non-homogeneous adhesion properties. In addition, the homogeneity of the adhesion properties is dependent upon the chemical species used to functionalize the surface. Force volume (FV) imaging was utilized to map the adhesion of the fabricated substrates with high-resolution. The FV studies revealed that the hydrophobicity of the surface is not uniform despite the fact that the surface was functionalized with the same polyelectrolyte. The analysis methodology we report here opens the possibility to design better surfaces for future tissue engineering applications. DA - 2005/9/15/ PY - 2005/9/15/ DO - 10.1016/j.talanta.2005.06.033 VL - 67 IS - 3 SP - 503-506 J2 - Talanta LA - en OP - SN - 0039-9140 UR - http://dx.doi.org/10.1016/j.talanta.2005.06.033 DB - Crossref KW - AFM KW - adhesion KW - polyelectrolytes ER - TY - JOUR TI - Templates for DNA-templated Fe3O4 nanoparticles AU - Nyamjav, Dorjderem AU - Ivanisevic, Albena T2 - Biomaterials AB - Two different strategies are reported that result in the site-specific placement of long DNA molecules, templated with Fe(3)O(4) nanoparticles, on SiO(x) surfaces. The strategies combine solution templating of inorganic nanoparticles onto biomolecules, molecular combing, the layer-by-layer method, and dip-pen nanolithography (DPN). In one methodology, the first step is to place and stretch DNA molecules via a DPN template containing features of poly(allylamine hydrochloride) (PAH). In the second step the elongated DNA is templated with Fe(3)O(4) nanoparticles allowing them to assemble onto the DNA molecules based on electrostatic interactions. In the second methodology, DPN templates composed of PSS patterns are used to comb in a site-specific manner DNA molecules that have been pre-tempated in solution with the Fe(3)O(4) nanoparticles. The templates generated by the two methods can serve as building blocks for the fabrication of future higher order assemblies. DA - 2005/5// PY - 2005/5// DO - 10.1016/j.biomaterials.2004.07.025 VL - 26 IS - 15 SP - 2749-2757 J2 - Biomaterials LA - en OP - SN - 0142-9612 UR - http://dx.doi.org/10.1016/j.biomaterials.2004.07.025 DB - Crossref KW - lithography KW - nanoparticles KW - DNA ER - TY - JOUR TI - Chromophore binding to in vitro engineered bio-mimetic surfaces AU - Kinsella, Joseph M. AU - Ivanisevic, Albena T2 - Applied Surface Science AB - In the retina, a chromophore isomerizes and the protein to which it binds changes shape. In this proof-of-concept experiment we engineer an artificial surface to mimic the physiochemical environment of the retina and the key reaction of the visual cycle. We immobilized small peptides on silicon and assessed changes in their surface properties upon chromophore binding via ellipsometry, X-ray photoelectron spectroscopy and atomic force microscopy. Our observations suggest that when binding occurs it is accompanied by changes in the properties of the film composed of surface-anchored peptides. DA - 2005/4// PY - 2005/4// DO - 10.1016/j.apsusc.2004.09.108 VL - 243 IS - 1-4 SP - 7-10 J2 - Applied Surface Science LA - en OP - SN - 0169-4332 UR - http://dx.doi.org/10.1016/j.apsusc.2004.09.108 DB - Crossref KW - bio-mimetic surfaces KW - peptides KW - X-ray photoelectron spectroscopy ER - TY - JOUR TI - Diamond-Hexagonal Semiconductor Nanocones with Controllable Apex Angle AU - Cao, Linyou AU - Laim, Lee AU - Ni, Chaoying AU - Nabet, Bahram AU - Spanier, Jonathan E. T2 - Journal of the American Chemical Society AB - We report on the synthesis of nanostructured and crystalline tapered Si and Ge polyhedra via metal-catalyzed chemical vapor deposition. These Si and Ge nanocones (SiNCs, GeNCs) possess tips with near-atomic sharpness, micron-scaled bases, hexagonal cross-sections, and controllable apex angles. High-resolution transmission electron microscopy, selected-area electron diffraction and Raman scattering spectroscopy and analysis indicate that the SiNCs are of the diamond-hexagonal Si(IV) phase. DA - 2005/10// PY - 2005/10// DO - 10.1021/ja0544814 VL - 127 IS - 40 SP - 13782-13783 J2 - J. Am. Chem. Soc. LA - en OP - SN - 0002-7863 1520-5126 UR - http://dx.doi.org/10.1021/ja0544814 DB - Crossref ER - TY - JOUR TI - Efficient self-assembly of transition metal oxide nanoclusters on silicon substrates AU - Cao, Linyou AU - Chai, Yang AU - Li, Pingjian AU - Shen, Zhiyong AU - Wu, Jinlei T2 - Thin Solid Films AB - Self-assembled monolayers (SAMs) of nanoclusters (< 10 nm) on silicon wafer have been prepared via simply immersing the substrate into a FeCl3/HCl solution. The clusters are hydrous iron oxide resulting from the hydrolysis of FeCl3, and their deposition is driven by the electrostatic attraction between the clusters and the substrate, the surface groups of which are oppositely charged at suitable pH value. HCl is used to enhance the repulsive force among the clusters and cause them uniformly distributed; in this regard, it can be replaced by KCl, NH4Cl, or NH2·HCl. This result provides a general guidance to prepare self-assemblies of transition metal oxide nanoclusters onto silicon substrates and others with appropriate hydroxyl (–OH) groups. DA - 2005/12// PY - 2005/12// DO - 10.1016/j.tsf.2005.06.022 VL - 492 IS - 1-2 SP - 13-18 J2 - Thin Solid Films LA - en OP - SN - 0040-6090 UR - http://dx.doi.org/10.1016/j.tsf.2005.06.022 DB - Crossref KW - nanoparticles KW - self-assembly KW - transition metal oxide KW - electrostatic interaction ER - TY - JOUR TI - Surface-Enhanced Raman Scattering ofp-Aminothiophenol on a Au(core)/Cu(shell) Nanoparticle Assembly AU - Cao, Linyou AU - Diao, Peng AU - Tong, Lianming AU - Zhu, Tao AU - Liu, Zhongfan T2 - ChemPhysChem AB - Abstract Surface‐enhanced Raman scattering (SERS) of p ‐aminothiophenol (PATP) molecules adsorbed onto assemblies of Au(core)/Cu(shell) nanoparticles is reported. We compare it with the SERS spectrum of PATP adsorbed onto gold nanoparticles: both the absolute and relative scattered intensities of various bands in the two spectra are very different. The difference in relative intensity can be ascribed to chemical effects; the chemical enhancement ratio of the two substrates is ≈3–5. A theoretical analysis based on a charge‐transfer model is carried out, which yields a consistent result and shows that the difference in chemical enhancement is mainly due to the state densities and Fermi levels of the substrates. The difference in absolute intensity originates from electromagnetic (EM) enhancement. EM enhancement of Au(core)/Cu(shell) nanoparticles is unlike that of single‐component gold or copper SERS‐active substrates. The core/shell particle size for optimal enhancement is about 20 nm in the case of a 632.8 nm incident laser (the size ratio of the core and shell layers is about 0.6). DA - 2005/5/13/ PY - 2005/5/13/ DO - 10.1002/cphc.200400254 VL - 6 IS - 5 SP - 913-918 J2 - ChemPhysChem LA - en OP - SN - 1439-4235 1439-7641 UR - http://dx.doi.org/10.1002/cphc.200400254 DB - Crossref KW - copper KW - gold KW - nanostructures KW - Raman spectroscopy KW - self-assembly ER - TY - JOUR TI - Contribution of low-temperature degrees of freedom to the anisotropy in Co/CoO exchange coupled bilayers AU - Venus, D. AU - Hunte, F. AU - Dan Dahlberg, E. T2 - Journal of Magnetism and Magnetic Materials AB - Abstract Measurements of the transverse magnetic AC-susceptibility χ ( T ) of exchange coupled polycrystalline Co/CoO bilayers have been made via the anisotropic magnetoresistance using a small AC field of 2–5 Oe and frequencies from 40 to 400 Hz. A step increase in Re χ is observed at 50–100 K, with an accompanying dissipation peak in Im χ . This feature is independent of the CoO thickness, but its dispersion with frequency suggests a thermally activated degree of freedom with an activation energy Ea∼150 K. This is consistent with a contribution to the anisotropy field due to the dynamics of the ferromagnetic rather than the antiferromagnetic grains. DA - 2005/2// PY - 2005/2// DO - 10.1016/j.jmmm.2004.09.038 VL - 286 SP - 191-195 J2 - Journal of Magnetism and Magnetic Materials LA - en OP - SN - 0304-8853 UR - http://dx.doi.org/10.1016/j.jmmm.2004.09.038 DB - Crossref KW - interfacial exchange KW - exchange anisotropy KW - exchange bias KW - anisotropic magnetoresistance KW - Co/CoO KW - magnetic susceptibility ER - TY - JOUR TI - Emission properties of a-plane GaN grown by metal-organic chemical-vapor deposition AU - Paskov, P. P. AU - Schifano, R. AU - Monemar, B. AU - Paskova, T. AU - Figge, S. AU - Hommel, D. T2 - Journal of Applied Physics AB - We report on the emission properties of nonpolar a-plane GaN layers grown on r-plane sapphire. Temperature-, excitation-density-, and polarization-dependent photoluminescences and spatially resolved microphotoluminescence and cathodoluminescence are employed in order to clarify the nature of the different emission bands in the 3.0–3.5eV spectral range. In the near band-edge region the emission lines of the donor-bound excitons (3.472eV) and free excitons (3.478eV) are resolved in the polarized low-temperature spectra, indicating a good quality of the layers. At low energies two other emissions bands with intensity and shape varying with the excited area are observed. The 3.42eV emission commonly attributed to the excitons bound to basal plane stacking faults shows thermal quenching with two activation energies (7 and 30meV) and an S-shaped temperature dependence of the peak position. This behavior is analyzed in terms of hole localization in the vicinity of the stacking faults. The emission band that peaked at 3.29eV is found to blueshift and saturate with increasing excitation intensity. The spatially resolved cathodoluminesence measurements show that the emission is asymmetrically distributed around the triangular-shaped pits occurring at the surface. The 3.29eV emission is suggested to involve impurities, which decorate the partial dislocation terminating the basal stacking faults. DA - 2005/11// PY - 2005/11// DO - 10.1063/1.2128496 VL - 98 IS - 9 SP - 093519 J2 - Journal of Applied Physics LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.2128496 DB - Crossref ER - TY - JOUR TI - Donor-acceptor pair emission enhancement in mass-transport-grown GaN AU - Paskova, T. AU - Arnaudov, B. AU - Paskov, P. P. AU - Goldys, E. M. AU - Hautakangas, S. AU - Saarinen, K. AU - Södervall, U. AU - Monemar, B. T2 - Journal of Applied Physics AB - A dominating donor-acceptor pair (DAP) emission at about 3.27eV is observed in the photoluminescence and cathodoluminescence spectra of intentionally undoped mass-transport (MT)-grown GaN, while only a weak presence of the DAP emission is recorded in the as-grown hydride vapor phase epitaxial GaN. A comparative study of impurity and native defect incorporation in the as-grown and MT GaN was performed, showing a significant increase of oxygen and empty clusters involving Ga vacancy and oxygen in the MT GaN. Based on the observed results as well as on doping analysis of the structure and kinetic analysis of the emission intensities, we propose an acceptorlike complex, creating a state as a semiclassical potential well near the valence-band top due to the local tensile strain caused by the empty clusters to be responsible for the dominating behavior of the DAP emission. DA - 2005/8// PY - 2005/8// DO - 10.1063/1.1994943 VL - 98 IS - 3 SP - 033508 J2 - Journal of Applied Physics LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.1994943 DB - Crossref ER - TY - JOUR TI - Structural characteristics and lattice parameters of hydride vapor phase epitaxial GaN free-standing quasisubstrates AU - Darakchieva, V. AU - Paskova, T. AU - Paskov, P. P. AU - Monemar, B. AU - Ashkenov, N. AU - Schubert, M. T2 - Journal of Applied Physics AB - We have studied the lattice parameters of hydride vapor phase epitaxy (HVPE)-GaN quasisubstrates in relation to their structural properties. Layers grown on single-layer metalorganic vapor phase epitaxy (MOVPE) templates and on epitaxial lateral overgrown MOVPE templates are characterized by Raman scattering, high-resolution x-ray diffraction, and reciprocal space mapping. The strain relaxation in the films versus their thickness was found to proceed similarly in the GaN samples grown using the two types of templates but the strain saturates at different nonzero levels. The lattice parameters of relatively thin HVPE-GaN free-standing quasisubstrates indicate that no total strain relaxation is achieved after the sapphire removal. The lattice parameters of the thick quasisubstrates grown on different templates are not affected by the separation process and are found to have values very close to the reference strain-free lattice parameters of GaN powder. DA - 2005/1// PY - 2005/1// DO - 10.1063/1.1823024 VL - 97 IS - 1 SP - 013517 J2 - Journal of Applied Physics LA - en OP - SN - 0021-8979 1089-7550 UR - http://dx.doi.org/10.1063/1.1823024 DB - Crossref ER - TY - JOUR TI - Properties of nonpolar a-plane GaN films grown by HVPE with AlN buffers AU - Paskova, T. AU - Darakchieva, V. AU - Paskov, P.P. AU - Birch, J. AU - Valcheva, E. AU - Persson, P.O.A. AU - Arnaudov, B. AU - Tungasmitta, S. AU - Monemar, B. T2 - Journal of Crystal Growth AB - The influence of high temperature AlN buffer layers on the morphology, structural and optical characteristics of a-plane GaN grown by hydride vapour phase epitaxy on r-plane sapphire was investigated. While the morphology of the a-GaN was found to be significantly improved by using a-plane AlN buffer layer similarly to the effect observed in c-plane hydride vapour phase epitaxy GaN growth, the microstructure ensemble was revealed to be more complicated in comparison to that of the c-plane GaN. Higher dislocation density and prismatic stacking faults were observed. Moreover, in-plane anisotropic structural characteristics were revealed by high resolution X-ray diffraction employing azimuthal dependent and edge X-ray measurement symmetric geometry. In addition, the near band edge photoluminescence peaks, red-shifted with respect to that in c-plane GaN were observed. The latter were explained by the influence of the higher defect density and more complex strain distribution. DA - 2005/7// PY - 2005/7// DO - 10.1016/j.jcrysgro.2005.03.013 VL - 281 IS - 1 SP - 55-61 J2 - Journal of Crystal Growth LA - en OP - SN - 0022-0248 UR - http://dx.doi.org/10.1016/j.jcrysgro.2005.03.013 DB - Crossref KW - GaN KW - a-plane KW - AlN buffer KW - morphology KW - microstructure KW - strain KW - PL KW - HRXRD ER - TY - JOUR TI - Optoelectronic devices on bulk GaN AU - Figge, S. AU - Böttcher, T. AU - Dennemarck, J. AU - Kröger, R. AU - Paskova, T. AU - Monemar, B. AU - Hommel, D. T2 - Journal of Crystal Growth AB - The homoeptaxial fabrication of GaN-based devices has advantages against heteroepitaxial realization on substrates such as sapphire or SiC, since heteroepitaxy implies a lot of problems like lattice mismatch, different thermal expansion coefficients, and needs an extensive optimization of the growth at the heterointerface. In this paper we will discuss GaN-based light-emitting devices grown by homoepitaxy in comparison to devices grown on sapphire. A special emphasis is laid on the pretreatment of the GaN substrate and the device characteristics on different substrates. In detail will be discussed the advantages of the higher thermal conductivity of GaN and how this effects the device performance. DA - 2005/7// PY - 2005/7// DO - 10.1016/j.jcrysgro.2005.03.017 VL - 281 IS - 1 SP - 101-106 J2 - Journal of Crystal Growth LA - en OP - SN - 0022-0248 UR - http://dx.doi.org/10.1016/j.jcrysgro.2005.03.017 DB - Crossref KW - hydride vapor phase epitaxy KW - metalorganic vapor phase epitaxy KW - nitrides ER - TY - JOUR TI - Nonpolara-plane HVPE GaN: growth and in-plane anisotropic properties AU - Paskova, T. AU - Darakchieva, V. AU - Paskov, P. P. AU - Birch, J. AU - Valcheva, E. AU - Persson, P. O. �. AU - Arnaudov, B. AU - Tungasmita, S. AU - Monemar, B. T2 - physica status solidi (c) AB - Nonpolar GaN thick films with [11-20] orientation were grown on [1-102] oriented sapphire by hydride vapour phase epitaxy (HVPE) utilizing reactively sputtered AlN buffers. Growth rate and microstructure of such films were investigated and compared to those in HVPE [0001] oriented GaN thick films. The structural parameters show an angular azimuth dependence implying in-plane non-homogeneity. The lattice parameters and strain components were determined by using plane and edge symmetric measurement geometries. A red shift observed in the near band edge photoluminescence is explained by the specific strain distribution studied independently by X-ray diffraction. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) DA - 2005/5// PY - 2005/5// DO - 10.1002/pssc.200461481 VL - 2 IS - 7 SP - 2027-2031 J2 - phys. stat. sol. (c) LA - en OP - SN - 1610-1634 1610-1642 UR - http://dx.doi.org/10.1002/pssc.200461481 DB - Crossref ER - TY - JOUR TI - Photoluminescence of GaN/AlN superlattices grown by MOCVD AU - Paskov, P. P. AU - Bergman, J. P. AU - Darakchieva, V. AU - Paskova, T. AU - Monemar, B. AU - Iwaya, M. AU - Kamiyama, S. AU - Amano, H. AU - Akasaki, I. T2 - physica status solidi (c) AB - We report on the emission properties of GaN/AlN superlattice (SL) structures grown by MOCVD. A set of samples with AlN thickness below 3 nm and different well/barrier thickness ratios has been studied. The SLs with a period between 3 and 8 nm show a photoluminescence (PL) peak in the range 3.3–3.9 eV with a full width at half maximum of about 100 meV. The difference in the transition energies, linewidths and recombination dynamics is described in terms of varying polarization field and electron filling in the wells. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) DA - 2005/5// PY - 2005/5// DO - 10.1002/pssc.200461367 VL - 2 IS - 7 SP - 2345-2348 J2 - phys. stat. sol. (c) LA - en OP - SN - 1610-1634 1610-1642 UR - http://dx.doi.org/10.1002/pssc.200461367 DB - Crossref ER - TY - JOUR TI - Thrust force, torque, and tool wear in drilling the bulk metallic glass AU - Bakkal, Mustafa AU - Shih, Albert J. AU - McSpadden, Samuel B. AU - Scattergood, Ronald O. T2 - International Journal of Machine Tools and Manufacture AB - The thrust force, torque, and tool wear in drilling of Zr-based bulk metallic glass (BMG) material are investigated. Drilling the BMG at high speed generates the chip light emission, high tool temperature, and severe tool wear. At low spindle speed, the BMG work-material builds up at the major and margin cutting edges and may break the drill. A range of feasible spindle speed and feed rate for the efficient drilling of BMG without the detrimental chip light emission and cutting edge work-material build-up has been identified in this study. Under the same drilling condition, the WC-Co tool generally requires less thrust force and about the same torque than the high-speed steel tool. The progressive wear of the major and margin cutting edges for BMG drilling is examined. Severe drill wear is associated with the bright BMG chip light emission. Without chip light emission, the drill wear is visible but not severe. This study concluded that precision holes in BMG could be generated with proper selection of tooling and process parameters. DA - 2005/6// PY - 2005/6// DO - 10.1016/j.ijmachtools.2004.11.005 VL - 45 IS - 7-8 SP - 863-872 J2 - International Journal of Machine Tools and Manufacture LA - en OP - SN - 0890-6955 UR - http://dx.doi.org/10.1016/j.ijmachtools.2004.11.005 DB - Crossref KW - bulk metallic glass KW - drilling KW - drilling force and torque KW - drill wear ER - TY - JOUR TI - Flow Control through Polymer-Grafted Smart Nanofluidic Channels:  Molecular Dynamics Simulations AU - Adiga, Shashishekar P. AU - Brenner, Donald W. T2 - Nano Letters AB - Presented are results of molecular dynamics simulations that demonstrate flow gating through a polymer-grafted nanopore as a function of effective solvent quality. Analysis of density and flow profiles from the simulations show that the difference in drag force exerted on the flowing solvent due to different polymer brush configurations produces the effective fluid gating. Shear-induced permeability changes through these nanopores has also been investigated. These results establish a critical starting point in nanofluidics from which continuum modeling can be developed to design this emerging class of smart nanoporous materials with tailor-made properties. DA - 2005/12// PY - 2005/12// DO - 10.1021/nl051843x VL - 5 IS - 12 SP - 2509-2514 J2 - Nano Lett. LA - en OP - SN - 1530-6984 1530-6992 UR - http://dx.doi.org/10.1021/nl051843x DB - Crossref ER - TY - JOUR TI - Evaluation of mechanical properties using shear–punch testing AU - Guduru, R.K. AU - Darling, K.A. AU - Kishore, R. AU - Scattergood, R.O. AU - Koch, C.C. AU - Murty, K.L. T2 - Materials Science and Engineering: A AB - The evaluation of mechanical properties like yield and ultimate tensile strengths from shear–punch tests is important when the availability of material is limited. A shear–punch test setup was built in our laboratory and the mechanical properties for different materials; mild steel, pure Al, Zn, brass (Cu–30% Zn by wt.), Al 6061, Austenitic and Martensitic stainless steels were evaluated. A new method using 1% offset criterion in conjunction with normalized shear–punch curves was used to measure the shear yield strength. A linear correlation between the shear data and tensile data was established for yield and ultimate strengths. The variation of the yield and ultimate shear strength was studied as a function of the sample thickness and die–punch clearance for soft, medium and high strength materials. DA - 2005/3// PY - 2005/3// DO - 10.1016/j.msea.2004.12.048 VL - 395 IS - 1-2 SP - 307-314 J2 - Materials Science and Engineering: A LA - en OP - SN - 0921-5093 UR - http://dx.doi.org/10.1016/j.msea.2004.12.048 DB - Crossref KW - shear-punch test KW - mechanical properties KW - yield strengths specimen thickness KW - die-punch clearance ER - TY - JOUR TI - Creep deformation characteristics of tin and tin-based electronic solder alloys AU - Mathew, M. D. AU - Yang, H. AU - Movva, S. AU - Murty, K. L. T2 - Metallurgical and Materials Transactions A DA - 2005/1// PY - 2005/1// DO - 10.1007/s11661-005-0142-z VL - 36 IS - 1 SP - 99-105 J2 - Metall and Mat Trans A LA - en OP - SN - 1073-5623 1543-1940 UR - http://dx.doi.org/10.1007/s11661-005-0142-z DB - Crossref ER - TY - JOUR TI - Breakthroughs in Optimization of Mechanical Properties of Nanostructured Metals and Alloys AU - Koch, C. C. AU - Youssef, K. M. AU - Scattergood, R. O. AU - Murty, K. L. T2 - Advanced Engineering Materials AB - Abstract While nanocrystalline metals can have strength and hardness values factors of 10 or more greater than their conventional grain size counterparts, ductility in tension has been disappointing, typically less than 2% elongation. This paper reviews the limitations to ductility in nanocrystalline materials and presents the results of recent breakthroughs wherein both high strength and good ductility are observed. DA - 2005/9// PY - 2005/9// DO - 10.1002/adem.200500094 VL - 7 IS - 9 SP - 787-794 J2 - Adv. Eng. Mater. LA - en OP - SN - 1438-1656 1527-2648 UR - http://dx.doi.org/10.1002/adem.200500094 DB - Crossref ER - TY - JOUR TI - Magnetic properties of Mn-doped GaN andp-i-n junctions AU - Reed, M.L. AU - Reed, M.J. AU - Luen, M.O. AU - Berkman, E.A. AU - Arkun, F.E. AU - Bedair, S.M. AU - Zavada, J.M. AU - El-Masry, N. A. T2 - physica status solidi (c) AB - We report on the growth and magnetic properties of GaMnN films and p-i-n junctions grown by metal-organic chemical vapor deposition. The magnetic properties of MOCVD grown GaMnN were found to depend upon the type and concentration of the co-dopant. Si or Mg co-doping of GaMnN films led to either ferromagnetic or paramagnetic behavior depending on the concentration. The magnetic properties within the GaMnN material system appear to correlate with the position of the Fermi level. Ferromagnetism was observed only when the Fermi energy level was within or very close to the Mn energy band. The presence of the Fermi energy level within the Mn energy band allows the presence of carriers that mediate ferromagnetism. These results further confirm that the ferromagnetic properties result from a solid solution of Mn in the GaN. Mn-doped GaN p-i-n junctions which were grown to study the effect of the magnetic properties on the I/V characteristics. These devices consist of GaN:Si/GaMnN/GaN:Mg layers grown by metal-organic chemical vapor deposition. The carrier concentrations for the n and p-type layers are ∼5 × 1018/cm3 and 1 × 1018/cm3 respectively, where the GaMnN i layer is approximately 0.2–0.45 µm thick with up to 0.5% Mn. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) DA - 2005/5// PY - 2005/5// DO - 10.1002/pssc.200461517 VL - 2 IS - 7 SP - 2403-2406 J2 - phys. stat. sol. (c) LA - en OP - SN - 1610-1634 1610-1642 UR - http://dx.doi.org/10.1002/pssc.200461517 DB - Crossref ER - TY - JOUR TI - Polarity control of GaN thin films grown by metalorganic vapor phase epitaxy AU - Collazo, R. AU - Mita, S. AU - Schlesser, R. AU - Sitar, Z. T2 - physica status solidi (c) AB - Control of the polarity of GaN thin films grown on c-plane sapphire by low-pressure metalorganic vapor phase epitaxy has been achieved. Growth of either polarity was realized by identifying and selecting appropriate substrate pre-treatments and AlN LT-buffer growth conditions. N-face (–c) GaN films were only obtained by pre-nitridation of the sapphire substrate after a H2 anneal. Smooth films of each type of polarity were obtained by using N2 as a transport and dilution gas and a V/III ratio of less than 500. The same growth rate of 1.2 µm/h was observed for both types of polarities under the same growth conditions. Further analysis of the growth conditions demonstrated that by using N2 as the dilution gas the transport was mass-transfer limited. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) DA - 2005/5// PY - 2005/5// DO - 10.1002/pssc.200461546 VL - 2 IS - 7 SP - 2117-2120 J2 - phys. stat. sol. (c) LA - en OP - SN - 1610-1634 1610-1642 UR - http://dx.doi.org/10.1002/pssc.200461546 DB - Crossref ER - TY - JOUR TI - Growth of gallium nitride via iodine vapor phase growth AU - Mecouch, W. J. AU - Reitmeier, Z. J. AU - Park, J.-S. AU - Davis, R. F. AU - Sitar, Z. T2 - physica status solidi (c) AB - Thick layers of gallium nitride have been deposited on 1µm thick MOVPE GaN(0001) thin film substrates using a novel vertical iodine vapor phase epitaxy system. The system features three concentric flow zones that separate the reactant gasses until they reached the substrate. Nitrogen flows through the innermost zone and delivers iodine vapor from an external bubbler to the molten Ga maintained at ∼1040 °C and GaI to the substrate; high-purity ammonia flows through the outermost zone; and nitrogen flows through the middle zone to prevent reaction between the growth species at the GaI nozzle. Growth rates greater than 75 µm/hr have been achieved at a V/III ratio of 75. The use of higher V/III ratios resulted in lower growth rates. Optical microscopy of the final growth surfaces revealed spiral hillocks with base diameters as large as 1mm. Increased Ga in the vapor phase resulted in a duplex microstructure containing both hillocks and faceted, oriented crystals overgrowing the hillocks. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) DA - 2005/5// PY - 2005/5// DO - 10.1002/pssc.200461532 VL - 2 IS - 7 SP - 2129-2132 J2 - phys. stat. sol. (c) LA - en OP - SN - 1610-1634 1610-1642 UR - http://dx.doi.org/10.1002/pssc.200461532 DB - Crossref ER - TY - JOUR TI - Polarity and morphology in seeded growth of bulk AlN on SiC AU - Dalmau, R. AU - Schlesser, R. AU - Sitar, Z. T2 - physica status solidi (c) AB - Growth of AlN bulk crystals on on-axis and off-axis (0001), Si-face SiC seeds was performed by physical vapor transport (PVT) using an AlN powder source. AlN layers between 0.1–3 mm thickness were grown on inch-sized seeds. Cracks formed in the AlN layers due to the thermal expansion mismatch between AlN and SiC were observed to decrease with increasing AlN thickness. AlN grown on on-axis SiC was primarily Al-polar, but contained N-polar inversion domains (IDs) revealed buy wet etching in hot, aqueous phosphoric acid or potassium hydroxide solutions. IDs were not observed in crystals grown on off-axis seeds. Using X-ray diffraction and scanning electron microscopy results, the influence of SiC seed orientation on the polarity and morphology of the AlN layers is discussed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) DA - 2005/5// PY - 2005/5// DO - 10.1002/pssc.200461511 VL - 2 IS - 7 SP - 2036-2039 J2 - phys. stat. sol. (c) LA - en OP - SN - 1610-1634 1610-1642 UR - http://dx.doi.org/10.1002/pssc.200461511 DB - Crossref ER - TY - JOUR TI - Raman, photoluminescence and absorption studies on high quality AlN single crystals AU - Senawiratne, J. AU - Strassburg, M. AU - Dietz, N. AU - Haboeck, U. AU - Hoffmann, A. AU - Noveski, V. AU - Dalmau, R. AU - Schlesser, R. AU - Sitar, Z. T2 - physica status solidi (c) AB - High quality AlN single crystals grown by physical vapour transport and by sublimation of AlN powder were investigated by Raman, photoluminescence (PL) and absorption spectroscopy. Absorption edges of the AlN single crystals varying from 4.1 eV to 5.9 eV as determined by transmission measurements. Near band edge absorption, PL and glow discharge mass spectroscopy identified impurities such as oxygen, silicon, carbon, and boron that contribute to the absorption and emission bands below the bandgap. The absorption coefficients were derived from UV (6 eV) to FIR (60 meV) spectral range. The exact crystal orientation of the samples, and their low carrier density were confirmed by Raman spectroscopy. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) DA - 2005/5// PY - 2005/5// DO - 10.1002/pssc.200461509 VL - 2 IS - 7 SP - 2774-2778 J2 - phys. stat. sol. (c) LA - en OP - SN - 1610-1634 1610-1642 UR - http://dx.doi.org/10.1002/pssc.200461509 DB - Crossref ER - TY - CONF TI - Properties of titanium-nitride for high level waste packaging enhancement AU - Scheffing, C.C. AU - Yim, M.-S. AU - Bourham, M. AU - Kasichainula, J. C2 - 2005/// C3 - Transactions of the American Nuclear Society DA - 2005/// VL - 93 SP - 709-710 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-33244457450&partnerID=MN8TOARS ER - TY - JOUR TI - Dynamic Behavior of the Telomerase RNA Hairpin Structure and its Relationship to Dyskeratosis Congenita AU - Yingling, Yaroslava G. AU - Shapiro, Bruce A. T2 - Journal of Molecular Biology AB - In this paper, we present the results from a comprehensive study of nanosecond-scale implicit and explicit solvent molecular dynamics simulations of the wild-type telomerase RNA hairpin. The effects of various mutations on telomerase RNA dynamics are also investigated. Overall, we found that the human telomerase hairpin is a very flexible molecule. In particular, periodically the molecule exhibits dramatic structural fluctuations represented by the opening and closing of a non-canonical base-pair region. These structural deviations correspond to significant disruptions of the direct hydrogen bonding network in the helix, widening of the major groove of the hairpin structure, and causing several U and C nucleotides to protrude into the major groove from the helix permitting them to hydrogen bond with, for example, the P3 domain of the telomerase RNA. We suggest that these structural fluctuations expose a nucleation point for pseudoknot formation. We also found that mutations in the pentaloop and non-canonical region stabilize the hairpin. Moreover, our results show that the hairpin with dyskeratosis congenita mutations is more stable and less flexible than the wild-type hairpin due to base stacking in the pentaloop. The results from our molecular dynamics simulations are in agreement with experimental observations. In addition, they suggest a possible mechanism for pseudoknot formation based on the dynamics of the hairpin structure and also may explain the mutational aspects of dyskeratosis congenita. DA - 2005/4// PY - 2005/4// DO - 10.1016/j.jmb.2005.02.015 VL - 348 IS - 1 SP - 27-42 J2 - Journal of Molecular Biology LA - en OP - SN - 0022-2836 UR - http://dx.doi.org/10.1016/j.jmb.2005.02.015 DB - Crossref KW - telomerase KW - RNA KW - molecular dynamics simulations KW - dyskeratosis congenita KW - pseudoknot ER - TY - JOUR TI - Coarse-Grained Model of the Interaction of Light with Polymeric Material: Onset of Ablation AU - Yingling, Yaroslava G. AU - Garrison, Barbara J. T2 - The Journal of Physical Chemistry B AB - A coarse-grained model has been developed for molecular dynamics simulations of the interaction of light with polymeric materials. The photon energy can result in a vibrational excitation (photothermal process) or disruption of a chemical bond (photochemical process) in a polymer. In the latter case, the formation of active radial sites and the occurrence of chemical reactions have to be taken into consideration. The novel feature of this model is the incorporation of chemical reactions into the united atom approximate representation of the polymer structure, which permits the study of laser ablation, degradation, or the effect of various chemical reactions on large time and length scales. The chemical reactions are included in the model in a probabilistic manner as in the kinetic Monte Carlo method. This model adopts physically and experimentally known quantities such as enthalpies and probabilities of reactions. Properties such as laser irradiation time, laser fluence, and wavelength are explicitly included. Moreover, no chemically correct interaction potential is required to incorporate the effects of chemical reactions on the dynamics of the system after energy deposition. We find that the model provides a plausible description of the essential processes. The laser-induced pressure relaxation is the main mechanism responsible for the onset of polymer ablation. Since the pressure relaxation processes are slow, there is a delay in the onset of ablation after the end of the laser pulse as is observed experimentally. The vaporization processes are not efficient for material removal, and the effect is minimal for both photochemical and photothermal processes. A lower fluence is needed for the onset of ablation with photochemical processes than photothermal processes. DA - 2005/9// PY - 2005/9// DO - 10.1021/jp0527711 VL - 109 IS - 34 SP - 16482-16489 J2 - J. Phys. Chem. B LA - en OP - SN - 1520-6106 1520-5207 UR - http://dx.doi.org/10.1021/jp0527711 DB - Crossref ER - TY - JOUR TI - Raman spectroscopy and imaging of ultralong carbon nanotubes AU - DOORN, SK AU - ZHENG, LX AU - O’CONNELL, MJ AU - al., T2 - JOURNAL OF PHYSICAL CHEMISTRY B AB - Raman spectroscopy and confocal Raman imaging with 514 nm excitation was performed on recently developed ultralong carbon nanotubes grown by the "fast-heating" chemical vapor deposition (CVD) method. The ultralong nanotubes are found to consist of both semiconducting and metallic types, with spectra that are consistent with the nanotubes being single walled. Characterization of nanotube diameters shows that short nanotubes appearing near the sample catalyst region have a broader distribution than is observed for the ultralong nanotubes. The narrow diameter distribution is determined by uniformity of catalyst particle size and gives additional evidence for the proposed "kite" mechanism for long nanotube growth. Raman imaging was performed over large length scales (up to 140 microm). Imaging reveals the ultralong nanotubes to be of high quality, with a very low defect density. Variations in G-band frequencies and intensity demonstrate the occurrence of minor structural changes and variations in nanotube-substrate interaction along the length of the nanotubes. Evidence also demonstrates that larger structural changes resulting in a full chirality change can occur in these nanotube types to produce a metal-to-semiconductor intramolecular junction. DA - 2005/// PY - 2005/// DO - 10.1021/jp0463159 VL - 109 IS - 9 SP - 3751-3758 ER - TY - JOUR TI - Raman spectral imaging of a carbon nanotube intramolecular junction AU - DOORN, SK AU - O’CONNELL, MJ AU - ZHENG, LX AU - al., T2 - PHYSICAL REVIEW LETTERS DA - 2005/// PY - 2005/// VL - 94 IS - 1 ER - TY - JOUR TI - Nucleation of deformation twins in nanocrystalline face-centered-cubic metals processed by severe plastic deformation AU - ZHU, YT AU - LIAO, XZ AU - SRINIVASAN, SG AU - al., T2 - JOURNAL OF APPLIED PHYSICS DA - 2005/// PY - 2005/// VL - 98 IS - 3 ER - TY - JOUR TI - Nanostructured TiNi-based shape memory alloys processed by severe plastic deformation AU - PUSHIN, VG AU - STOLYAROV, , VV AU - VALIEV, RZ AU - al., T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING DA - 2005/// PY - 2005/// VL - 410 SP - 386-389 ER - TY - JOUR TI - Influence of stacking fault energy on nanostructure formation under high pressure torsion AU - ZHAO, YH AU - LIAO, XZ AU - ZHU, YT AU - al., T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING AB - Copper, bronze (Cu–10 wt.% Zn) and brass (Cu–30 wt.% Zn) were deformed by high pressure torsion (HPT) under a pressure of 6 GPa for five rotations. The stacking fault energies (SFEs) of copper, bronze and brass are 78, 35 and 14 mJ/m2, respectively, and their average grain sizes after the HPT processing were about 84, 54 and 17 nm, respectively. Deformation twins were found in all samples and their densities increased with decreasing SFE. This work demonstrates that under the same conditions of HPT a low SFE promotes the formation of nanostructures and deformation twins. DA - 2005/// PY - 2005/// DO - 10.1016/j.msea.2005.08.074 VL - 410 SP - 188-193 KW - stacking fault energy KW - copper and copper alloys KW - high pressure torsion KW - microstructure KW - deformation twins ER - TY - JOUR TI - Influence of grain size on deformation mechanisms: An extension to nanocrystalline materials AU - Zhu, Yuntian T. AU - Langdon, Terence G. T2 - Materials Science and Engineering: A AB - The deformation mechanisms occurring in coarse-grained polycrystalline materials are now understood reasonably well. The primary deformation processes are associated with the intragranular movement of dislocations either through crystallographic slip at low temperatures or through a combination of dislocation climb and glide at high temperatures. Intergranular processes become important in polycrystalline materials with small grain sizes including stress-directed vacancy diffusion and grain boundary sliding. It has been shown using molecular dynamic simulations, and confirmed in experiments, that different processes may become important when the grain size is reduced to the nanometer level. Partial dislocation emission from grain boundaries becomes a dominant process at grain sizes of 10–50 nm and this leads to the formation of deformation twins even in materials with high stacking-fault energies such as aluminum. Grain boundary sliding also becomes dominant at grain sizes below ∼10 nm at low temperatures. This paper examines the influence of grain size on the deformation mechanisms in polycrystalline materials with special emphasis on the new mechanisms that become important at the nanocrystalline level. DA - 2005/11// PY - 2005/11// DO - 10.1016/j.msea.2005.05.111 VL - 409 IS - 1-2 SP - 234-242 J2 - Materials Science and Engineering: A LA - en OP - SN - 0921-5093 UR - http://dx.doi.org/10.1016/j.msea.2005.05.111 DB - Crossref KW - creep KW - deformation mechanisms KW - grain size KW - nanostructured materials KW - twinning ER - TY - JOUR TI - Formation mechanisms of nanostructures in stainless steel during high-strain-rate severe plastic deformation AU - XUE, Q AU - LIAO, XZ AU - ZHU, YT AU - al., T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING DA - 2005/// PY - 2005/// VL - 410 SP - 252-256 ER - TY - JOUR TI - Formation mechanism of fivefold deformation twins in nanocrystalline face-centered-cubic metals AU - ZHU, YT AU - LIAO, XZ T2 - APPLIED PHYSICS LETTERS DA - 2005/// PY - 2005/// VL - 86 IS - 10 ER - TY - JOUR TI - Enhanced mechanical properties in ultrafine grained 7075 Al alloy AU - ZHAO, YH AU - LIAO, XZ AU - ZHU, YT AU - al., T2 - JOURNAL OF MATERIALS RESEARCH DA - 2005/// PY - 2005/// VL - 20 IS - 2 SP - 288-291 ER - TY - JOUR TI - Effects of Eu interfacial mobility on the growth of epitaxial EuBa2Cu3O7-delta films AU - WANG, H AU - LIAO, XZ AU - XU, HF AU - al., T2 - APPLIED PHYSICS LETTERS AB - By inserting a thin YBa2Cu3O7−δ (Y123) seed layer, high quality EuBa2Cu3O7−δ (Eu123) films can grow with epitaxial c-axis orientation on SrTiO3 (STO) substrate without increasing the growth temperature. The interfacial structures of Eu123∕STO and Eu123∕Y123∕STO were investigated using scanning transmission electron microscopy. Results show that the Eu mobility on the STO substrate is very low at the regular deposition temperature. This leads to nonuniform composition distribution at the Eu123∕STO interface and a mixture of c-axis and a-axis growth. A thin Y123 seed layer greatly improves the Eu mobility and therefore facilitates high quality c-axis growth. DA - 2005/// PY - 2005/// DO - 10.1063/1.1881779 VL - 86 IS - 10 ER - TY - JOUR TI - Dry-sliding tribological properties of ultrafine-grained Ti prepared by severe plastic deformation AU - LA, PQ AU - MA, JQ AU - ZHU, YT AU - al., T2 - ACTA MATERIALIA DA - 2005/// PY - 2005/// VL - 53 IS - 19 SP - 5167-5173 ER - TY - JOUR TI - Deformation twinning in nanocrystalline metals AU - ZHU, YT T2 - JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE DA - 2005/// PY - 2005/// VL - 14 IS - 4 SP - 467-472 ER - TY - JOUR TI - Compact and dissociated dislocations in aluminum: Implications for deformation AU - SRINIVASAN, SG AU - LIAO, XZ AU - BASKES, MI AU - al., T2 - PHYSICAL REVIEW LETTERS DA - 2005/// PY - 2005/// VL - 94 IS - 12 ER - TY - JOUR TI - Use of phosphine as an n-type dopant source for vapor-liquid-solid growth of silicon nanowires AU - Wang, YF AU - Lew, KK AU - Ho, TT AU - Pan, L AU - Novak, SW AU - Dickey, EC AU - Redwing, JM AU - Mayer, TS T2 - Nano Letters AB - Phosphine (PH3) was investigated as an n-type dopant source for Au-catalyzed vapor-liquid-solid (VLS) growth of phosphorus-doped silicon nanowires (SiNWs). Transmission electron microscopy characterization revealed that the as-grown SiNWs were predominately single crystal even at high phosphorus concentrations. Four-point resistance and gate-dependent conductance measurements confirmed that electrically active phosphorus was incorporated into the SiNWs during VLS growth. A transition was observed from p-type conduction for nominally undoped SiNWs to n-type conduction upon the introduction of PH3 to the inlet gas. The resistivity of the n-type SiNWs decreased by approximately 3 orders of magnitude as the inlet PH3 to silane (SiH4) gas ratio was increased from 2 x 10(-5) to 2 x 10(-3). These results demonstrate that PH3 can be used to produce n-type SiNWs with properties that are suitable for electronic and optoelectronic device applications. DA - 2005/// PY - 2005/// DO - 10.1021/nl051442h VL - 5 IS - 11 SP - 2139-2143 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000233481700005&KeyUID=WOS:000233481700005 ER - TY - JOUR TI - Study on Axial and Radial Heterostructures of Si-Ge and Si-SiGe Nanowires. AU - Pan, L AU - Lew, K-K AU - Redwing, J AU - Dickey, E T2 - Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada AB - Journal Article Study on Axial and Radial Heterostructures of Si-Ge and Si-SiGe Nanowires Get access L Pan, L Pan Pennsylvania State University Search for other works by this author on: Oxford Academic Google Scholar K-K Lew, K-K Lew Pennsylvania State University Search for other works by this author on: Oxford Academic Google Scholar J Redwing, J Redwing Pennsylvania State University Search for other works by this author on: Oxford Academic Google Scholar E Dickey E Dickey Pennsylvania State University Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 11, Issue S02, 1 August 2005, Pages 1722–1723, https://doi.org/10.1017/S1431927605507505 Published: 01 August 2005 DA - 2005/// PY - 2005/// DO - 10.1017/S1431927605507505 VL - 11 Suppl 2 IS - S02 SP - 1722-3 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=MEDLINE&KeyUT=MEDLINE:24017729&KeyUID=MEDLINE:24017729 ER - TY - JOUR TI - Stranski-Krastanow growth of germanium on silicon nanowires AU - Pan, L AU - Lew, KK AU - Redwing, JM AU - Dickey, EC T2 - Nano Letters AB - There have been extensive studies of germanium (Ge) grown on planar silicon (Si) substrates by the Stranski-Krastanow (S-K) mechanism. In this study, we present S-K growth of Ge on Si nanowires. The Si nanowires were grown at 500 degrees C by a vapor-liquid-solid (VLS) method, using silane (SiH4) as the gaseous precursor. By switching the gas source from SiH4 to germane (GeH4) during the growth and maintaining the growth conditions, epitaxial Ge islands deposited on the outer surface of the initially formed Si nanowires. Transmission electron microscopy (TEM), scanning TEM, and energy-dispersive X-ray spectroscopy techniques were utilized to identify the thin wetting layer and the three-dimensional Ge islands formed around the Si core nanowires. Cross-sectional TEM verified the surface faceting of the Si core nanowires as well as the Ge islands. DA - 2005/// PY - 2005/// DO - 10.1021/nl050605z VL - 5 IS - 6 SP - 1081-1085 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000229729900016&KeyUID=WOS:000229729900016 ER - TY - JOUR TI - Interfacial Reactions Between Ni and BaTiO3: An Analytical Transmission Electron Microscopy Study. AU - Yang, G Y AU - Dickey, E C AU - Randall, C A T2 - Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada AB - Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005 DA - 2005/// PY - 2005/// DO - 10.1017/S1431927605502307 VL - 11 Suppl 2 IS - SUPPL. 2 SP - 232-3 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=MEDLINE&KeyUT=MEDLINE:24016988&KeyUID=MEDLINE:24016988 ER - TY - JOUR TI - Interfaces in Next Generation Ta and NbO Solid Electrolytic Capacitors. AU - Olszta, M AU - Sloppy, J AU - Wang, J AU - Dickey, E C T2 - Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada AB - Extract HTML view is not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button. Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005 DA - 2005/// PY - 2005/// DO - 10.1017/S1431927605508122 VL - 11 Suppl 2 IS - S02 SP - 578-9 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=MEDLINE&KeyUT=MEDLINE:24017160&KeyUID=MEDLINE:24017160 ER - TY - JOUR TI - Effect of diborane on the microstructure of boron-doped silicon nanowires AU - Pan, L AU - Lew, KK AU - Redwing, JM AU - Dickey, EC T2 - Journal of Crystal Growth AB - Boron-doped silicon (Si) nanowires, with nominal diameters of 80 nm, were grown via the vapor–liquid–solid (VLS) mechanism using gold (Au) as a catalyst and silane (SiH4) and diborane (B2H6) as precursors. The microstructure of the nanowires was studied by scanning electron microscopy, transmission electron microscopy and electron energy-loss spectroscopy. At lower B2H6 partial pressure and thus lower doping levels (⩽1×1018 cm−3), most of the boron-doped Si nanowires exhibited high crystallinity. At higher B2H6 partial pressure (∼2×1019 cm−3 doping level), the majority of the wires exhibited a core–shell structure with an amorphous Si shell (20–30 nm thick) surrounding a crystalline Si core. Au nanoparticles on the outer surface of the nanowires were also observed in structures grown with high B/Si gas ratios. The structural changes are believed to result from an increase in the rate of Si thin-film deposition on the outer surface of the nanowire at high B2H6 partial pressure, which produces the amorphous coating and also causes an instability at the liquid/solid interface resulting in a loss of Au during nanowire growth. DA - 2005/// PY - 2005/// DO - 10.1016/j.jcrysgro.2005.01.091 VL - 277 IS - 1-4 SP - 428-436 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000228737900068&KeyUID=WOS:000228737900068 ER - TY - JOUR TI - Effect of AlN interlayers on growth stress in GaN layers deposited on (111) Si AU - Raghavan, S AU - Weng, XJ AU - Dickey, E AU - Redwing, JM T2 - Applied Physics Letters AB - Thin (∼10nm) AlN interlayers have previously been used to mitigate stress and cracking in GaN epitaxial layers grown on Si substrates. However, multiple AlN interlayers are typically required for the growth of thick (&gt;1μm) GaN as the initial compressive mismatch stress introduced by the AlN interlayer transitions to a tensile stress within 0.5μm. To better understand the reasons for the transition, in situ monitoring and transmission electron microscopy have been used to study stress and structural evolution in undoped GaN layers deposited on high temperature (1050–1100°C) AlN interlayers by metal-organic chemical-vapor deposition. The results show that transition of the initial compressive stress to a final tensile stress is associated with a reduction in the density of dislocations introduced either by the pseudosubstrate or the interlayer itself. DA - 2005/// PY - 2005/// DO - 10.1063/1.2081128 VL - 87 IS - 14 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000232225700028&KeyUID=WOS:000232225700028 ER - TY - JOUR TI - Crystallographic Orientation Relationships and Interface Structures in Directionally Solidified LaB6-ZrB2 Eutectics. AU - Deng, H AU - Dickey, E AU - Paderno, Y AU - Paderno, V AU - Filippov, V T2 - Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada AB - Extract HTML view is not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button. Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005 DA - 2005/// PY - 2005/// DO - 10.1017/S1431927605503623 VL - 11 Suppl 2 IS - S02 SP - 1724-5 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=MEDLINE&KeyUT=MEDLINE:24017730&KeyUID=MEDLINE:24017730 ER - TY - JOUR TI - A novel approach to sintering nanocrystalline barium titanate ceramics AU - Polotai, A AU - Breece, K AU - Dickey, E AU - Randall, C AU - Ragulya, A T2 - Journal of the American Ceramic Society AB - A novel approach to pressureless sintering based on the combination of rapid‐rate sintering, rate‐controlled sintering, and two‐step sintering under a controlled atmosphere is proposed. This combined sintering method facilitates control of grain and pore morphology. The application of this sintering approach for pure nanocrystalline barium titanate powder enables the suppression of grain growth during the intermediate and final stages of sintering and the production of fully dense ceramics with 108 nm grain size. The grain growth factor is 3.5, which is three and 17 times smaller than rate‐controlled and conventional sintering, respectively. DA - 2005/// PY - 2005/// DO - 10.1111/j.1551-2916.2005.00552.x VL - 88 IS - 11 SP - 3008-3012 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000232773100004&KeyUID=WOS:000232773100004 ER - TY - JOUR TI - Phosphine oxide polymer for water-soluble nanoparticles AU - KIM, SW AU - KIM, S AU - TRACY, JB AU - JASANOFF, A AU - BAWENDI, MG T2 - JOURNAL OF THE AMERICAN CHEMICAL SOCIETY DA - 2005/// PY - 2005/// DO - 10.1021/ja043511f VL - 127 IS - 13 SP - 4556-4557 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000228089300007&KeyUID=WOS:000228089300007 ER - TY - JOUR TI - Exchange biasing and magnetic properties of partially and fully oxidized colloidal cobalt nanoparticles AU - TRACY, JB AU - WEISS, DN AU - DINEGA, DP AU - BAWENDI, MG T2 - PHYSICAL REVIEW B AB - Colloidal magnetic nanoparticles (NPs) have been applied in magnetic separations, in medicine and in biochemistry. They are also potentially applicable in magnetic recording media. In this paper, we report a systematic investigation of the magnetic properties of colloidal Co NPs after three extents of oxidation. The native sample has a thin (1.0 nm) CoO shell and exhibits no exchange biasing. The purposefully partially oxidized sample has a thicker CoO shell (3.2 nm), and is exchange biased. The sample fully oxidized to CoO loses exchange biasing. We observe three distinct magnetic properties that result from the finite-thickness antiferromagnet shell exchange coupled to a finite-size ferromagnet core, and from crystal and stoichiometric defects: (1) an enhancement of the thermal stability of the orientation of the magnetic moment due to exchange biasing in the partially oxidized sample, (2) a low-temperature paramagnetic response in the partially and fully oxidized samples due to defects in the CoO shell, and (3) an asymmetry in the field-dependent magnetization for the partially oxidized sample at low temperature due to small clusters of Co in a diffusion layer around the Co core. We propose a simple model to interpret these effects. DA - 2005/// PY - 2005/// DO - 10.1103/PhysRevB.72.064404 VL - 72 IS - 6 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000231564400071&KeyUID=WOS:000231564400071 ER - TY - JOUR TI - Engineering InAsxP1-x/InP/ZnSe III−V Alloyed Core/Shell Quantum Dots for the Near-Infrared AU - Kim, Sang-Wook AU - Zimmer, John P. AU - Ohnishi, Shunsuke AU - Tracy, Joseph B. AU - Frangioni, John V. AU - Bawendi, Moungi G. T2 - Journal of the American Chemical Society AB - Quantum dots with a core/shell/shell structure consisting of an alloyed core of InAsxP1-x, an intermediate shell of InP, and an outer shell of ZnSe were developed. The InAsxP1-x alloyed core has a graded internal composition with increasing arsenic content from the center to the edge of the dots. This compositional gradient results from two apparent effects: (1) the faster reaction kinetics of the phosphorus precursor compared to the arsenic precursor, and (2) a post-growth arsenic−phosphorus exchange reaction that increases the arsenic content. The cores have a zinc blend structure for all compositions and show tunable emission in the near-infrared (NIR) region. A first shell of InP leads to a red-shift and an increase in quantum yield. The final shell of ZnSe serves to stabilize the dots for applications in aqueous environments, including NIR biomedical fluorescence imaging. These NIR-emitting core/shell/shell InAsxP1-x/InP/ZnSe were successfully used in a sentinel lymph node mapping experiment. DA - 2005/8// PY - 2005/8// DO - 10.1021/ja0434331 VL - 127 IS - 30 SP - 10526-10532 J2 - J. Am. Chem. Soc. LA - en OP - SN - 0002-7863 1520-5126 UR - http://dx.doi.org/10.1021/ja0434331 DB - Crossref ER - TY - CONF TI - Defects in CoO dominate exchange biasing in Co(core)/CoO(shell) nanoparticles. AU - TRACY, JB AU - BAWENDI, MG C2 - 2005/// C3 - 229th National Meeting of the American-Chemical-Society DA - 2005/// VL - 229 SP - U976 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000228177707104&KeyUID=WOS:000228177707104 ER - TY - JOUR TI - Mitochondrial mutation detection using enhanced multiplex denaturing high-performance liquid chromatography AU - Bayat, A AU - Walter, J AU - Lamb, H AU - Marino, M AU - Ferguson, MWJ AU - Ollier, WER T2 - INTERNATIONAL JOURNAL OF IMMUNOGENETICS AB - Summary In this study, we investigated the presence of mutations within the mitochondrial genome in 40 Caucasian subjects using an enhanced multiplex denaturing high‐performance liquid chromatography (DHPLC) approach. The enhanced DHPLC approach has increased sensitivity and throughput, and reduced analysis time per individual sample compared to conventional methods. This technique involved amplifying the mitochondrial genome in 18 fragments ranging in size from 300 to 2000 bp using a novel proofreading polymerase (Optimase TM , Transgenomic Inc., Omaha, NE) with a low misincorporation rate. Fourteen of these fragments underwent subsequent restriction digestion using a combination of five restriction enzymes to enable multiplex DHPLC analysis; the remaining four underwent conventional DHPLC. Using this complete mitochondrial genome‐screening approach, we confirmed a number of previously reported mutations and additionally identified a large number of novel mutations using an enhanced DHPLC technique. DA - 2005/6// PY - 2005/6// DO - 10.1111/j.1744-313x.2005.00508.x VL - 32 IS - 3 SP - 199-205 SN - 1744-313X ER - TY - PAT TI - Scintillation detector, system and method providing energy and position information AU - Schreiner, R. S. AU - White, J. A. AU - Mayhugh, M. R. AU - Mataranza, G. AU - Rozsa, C. M. AU - Herr, D. J. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Patterning methods and systems using reflected interference patterns AU - Herr, D. J. C. AU - Joy, D. C. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Electrical device including dielectric layer formed by direct patterning process AU - Gleason, K. K. AU - Ober, C. AU - Herr, D. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Method for depositing in particular crystalline layers, and device for carrying out the method AU - Bremser, M. AU - Dauelsberg, M. AU - Strauch, G. K. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Multi-layer conductor-dielectric oxide structure AU - Maria, J.-P. AU - Kingon, A. AU - Dunn, G. J. AU - Streiffer, S. AU - Cheek, K. AU - Zhang, M.-X. AU - Savic, J. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Gallium nitride materials including thermally conductive regions AU - Borges, R. AU - Linthicum, K. J. AU - Weeks, T. W. AU - Gehrke, T. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Thin film capacitor with substantially homogenous stoichiometry AU - Basceri, C. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Structures and methods for enhancing capacitors in integrated circuits AU - Basceri, C. AU - Sandhu, G. S. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Semiconductor manufacturing process and apparatus for modifying in-film stress of thin films, and product formed thereby AU - Basceri, C. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Reactors having gas distributors and methods for depositing materials onto micro-device workpieces AU - Basceri, C. AU - Sandhu, G. S. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Mixed composition interface layer and method of forming AU - Basceri, C. AU - Sandhu, G. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Methods of forming rugged electrically conductive surfaces and layers AU - Pontoh, M. AU - Basceri, C. AU - Greattinger, T. M. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Methods of forming perovskite-type dielectric materials with chemical vapor deposition AU - Basceri, C. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Methods of forming conductive metal silicides by reaction of metal with silicon AU - Derderian, G. J. AU - Basceri, C. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Methods of forming conductive connections, and methods of forming nanofeatures AU - Basceri, C. AU - Derderian, G. J. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Methods of forming capacitor constructions AU - Basceri, C. AU - Derderian, G. J. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Method of forming haze-free BST films AU - Basceri, C. AU - Sandhu, G. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Method of forming a MIM capacitor with metal nitride electrode AU - Basceri, C. AU - Braettinger, T. M. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Method for controlling deposition of dielectric films AU - Basceri, C. AU - Gealy, D. AU - Sandhu, G. S. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Integrated capacitors fabricated with conductive metal oxides AU - Rhodes, H. E. AU - Visokay, M. AU - Graettinger, T. AU - Gealy, D. AU - Sandhu, G. AU - Basceri, C. AU - Cummings, S. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Haze-free BST films AU - Basceri, C. AU - Sandhu, G. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Gas delivery system for pulsed-type deposition processes used in the manufacturing of micro-devices AU - Basceri, C. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Dielectric cure for reducing oxygen vacancies AU - Basceri, C. AU - Sandhu, G. S. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Deposition methods AU - Sarigiannis, D. AU - Derderian, G. J. AU - Basceri, C. AU - Sandhu, G. S. AU - Gealy, F. D. AU - Carlson, C. M. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Conductive semiconductor structures containing metal oxide regions AU - Basceri, C. AU - Sandhu, G. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Chemical vapor deposition methods of forming barium strontium titanate comprising dielectric layers AU - Basceri, C. AU - Azola, N. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Chemical vapor deposition method for depositing a high k dielectric film AU - Basceri, C. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Capacitor constructions comprising perovskite-type dielectric materials and having different degrees of crystallinity within the perovskite-type dielectric materials AU - Basceri, C. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Atomic layer deposition apparatus and methods AU - Derderian, G. J. AU - Basceri, C. AU - Sandhu, G. S. AU - Sarigiannis, D. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - JOUR TI - Surfactant effects on carbon nanotube interactions with human keratinocytes AU - Monteiro-Riviere, Nancy A. AU - Inman, Alfred O. AU - Wang, Yunyu Y. AU - Nemanich, Robert J. T2 - NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE AB - Interactions of multiwalled carbon nanotubes (MWCNTs) with human epidermal keratinocytes (HEKs) were studied with respect to the effect of surfactant on dispersion of MWCNT aggregates and cytotoxicity. Our earlier studies had shown that the unmodified MWCNTs were localized within the cytoplasmic vacuoles of HEKs and elicited an inflammatory response. However, MWCNTs in solution tend to aggregate and, therefore, cells are exposed to large MWCNT aggregates. The purpose of this study was to find a surfactant that prevents the formation of large aggregates of MWCNTs without being toxic to the HEKs. HEKs were exposed to serial dilutions (10% to 0.1%) of L61, L92, and F127 Pluronic and 20 or 60 Tween for 24 hours. HEK viability, proportional to surfactant concentration, ranged from 27.1% to 98.5% with Pluronic F127; viability with the other surfactants was less than 10%. Surfactants dispersed and reduced MWCNT aggregation in medium. MWCNTs at 0.4 mg/mL in 5% or 1% Pluronic F127 were incubated with HEKs and assayed for interleukin 8 (IL-8). MWCNTs were cytotoxic to HEKs independent of surfactant exposure. In contrast, MWCNT-induced IL-8 release was reduced when exposed to 1% or 5% Pluronic F127 (P < .05). However, both MWCNTs and surfactant, alone or in combination, increased IL-8 release compared with control exposures at 12 and 24 hours. These results suggest that the surfactant-MWCNT interaction is more complex than simple dispersion alone and should be investigated to determine the mode of interaction. DA - 2005/12// PY - 2005/12// DO - 10.1016/j.nano.2005.10.007 VL - 1 IS - 4 SP - 293-299 SN - 1549-9642 KW - Surfactant KW - Multiwalled carbon nanotubes KW - Human epidermal keratinocytes ER - TY - PAT TI - Supermolecular structureS and devices made from same AU - Herr, D. J. C. AU - Zhirnov, V. V. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Second gallium nitride layers that extend into trenches in first gallium nitride layers AU - Zheleva, T. AU - Thomson, D. B. AU - Smith, S. A. AU - Linthicum, K. J. AU - Gehrke, T. AU - Davis, R. F. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Optoelectronic devices having arrays of quantum-dot compound semiconductor superlattices therein AU - Zhang, Z. AU - Misra, V. AU - Bedair, S. M. A. AU - Ozturk, M. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Methods of controlling oxygen partial pressure during annealing of a perovskite dielectric layer AU - Maria, J.-P. AU - Kingon, A. I. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - PAT TI - Culture system for mouse tracheal epithelial cells AU - Martin, L. D. AU - Adler, K. B. AU - Macchione, M. AU - Akley, N. J. AU - McKane, S. A. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - JOUR TI - Tunable CO2 transport through mixed polyether membranes AU - Patel, NP AU - Hunt, MA AU - Lin-Gibson, S AU - Bencherif, S AU - Spontak, RJ T2 - JOURNAL OF MEMBRANE SCIENCE AB - Gas-separation membranes composed of polyethers such as poly(ethylene glycol)diacrylate (PEGda) or poly(propylene glycol)diacrylate (PPGda) exhibit high CO2 solubility selectivity, which makes them attractive for use in H2 and air purification. In this work, we investigate the factors governing CO2 and H2 transport in mixed polyether matrices. Addition of semicrystalline poly(ethylene oxide)s to amorphous PEGda lowers the net CO2 permeability and CO2/H2 selectivity due to crystal formation. Gas permeation through the amorphous fraction, however, remains unaffected, confirming the existence of a molecular weight limit below which the entire membrane participates in gas transport. The permeabilities of CO2 and H2, as well as their activation energy of permeation, in miscible PEGda/PPGda blends follow the linear rule of mixtures over the temperature range explored. Incorporation of amine moieties employed in liquid membranes into either the PEGda matrix during crosslinking or the PEG backbone generally reduces CO2/H2 selectivity but occasionally improves CO2 permeability. DA - 2005/4/1/ PY - 2005/4/1/ DO - 10.1016/j.memsci.2004.11.003 VL - 251 IS - 1-2 SP - 51-57 SN - 1873-3123 KW - polyether KW - gas-separation membrane KW - reverse selectivity ER - TY - PCOMM TI - Transmission electron microscopy studies of the bonded SiC-SiC interface AU - Yushin, GN AU - Kvit, AV AU - Sitar, Z DA - 2005/8// PY - 2005/8// DO - 10.1007/s10853-005-0779-4 SP - 4369-4371 ER - TY - JOUR TI - Strategies and tactics for external corporate venturing AU - Markham, SK AU - Gentry, ST AU - Hume, D AU - Ramachandran, R AU - Kingon, AI T2 - RESEARCH-TECHNOLOGY MANAGEMENT AB - OVERVIEW:By providing a window on emerging technologies, market opportunities, new business models, and distribution channels, corporate venturing can be an important source of technological innovation for corporations. However, effective implementation requires a clear view of the objectives, dedication to understanding the process, and discipline. There are two major tactics for external investing: invest in a venture capital fund, or invest directly in a start-up company, and the strategy a company chooses should be tied to its objectives. For example, best-of-class companies whose objective is to acquire a window on technology will invest in VC funds to gain access to their wider deal flow. One of the most challenging aspects of corporate venturing is finding the right people, and corporations must be willing to devote significant time and resources to working closely with their portfolio companies if they wish to gain satisfactory value from their external investments. DA - 2005/// PY - 2005/// DO - 10.1080/08956308.2005.11657305 VL - 48 IS - 2 SP - 49-59 SN - 1930-0166 KW - venture capital KW - corporate venturing KW - external investment KW - new business development ER - TY - JOUR TI - Simultaneous elastic and electromechanical imaging by scanning probe microscopy: Theory and applications to ferroelectric and biological materials AU - Shin, J. AU - Rodriguez, B. J. AU - Baddorf, A. P. AU - Thundat, T. AU - Karapetian, E. AU - Kachanov, M. AU - Gruverman, A. AU - Kalinin, S. V. T2 - Journal of Vacuum Science & Technology. B, Microelectronics and Nanometer Structures DA - 2005/// PY - 2005/// VL - 23 IS - 5 SP - 2102-2108 ER - TY - JOUR TI - Property and morphology development in nanocomposite thermoplastic elastomer gels AU - Maanen, GJ AU - Seeley, SL AU - Capracotta, MD AU - White, SA AU - Bukovnik, RR AU - Hartmann, J AU - Martin, JD AU - Spontak, RJ T2 - LANGMUIR AB - Thermoplastic elastomer gels (TPEGs), molecular networks composed of a microphase-separated multiblock copolymer swollen to a large extent by a low-volatility midblock-selective solvent, are ubiquitous in a wide range of contemporary technologies, including home and office products, athletic equipment, and telecommunications devices. In this work, we investigate the effect of several network-forming nanoscale modifiers-two different silica nanoparticles, three different nanoclays, and a multiwalled carbon nanotube-on the property and morphology development of a TPEG prepared from a microphase-ordered poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) triblock copolymer imbibed with an EB-compatible aliphatic mineral oil. Dynamic rheological measurements of the resultant nanocomposite TPEGs confirm that addition of these modifiers affects the linear viscoelastic threshold and increases, to different extents, the dynamic elastic modulus, the dynamic yield stress, and the maximum operating temperature of the parent TPEG. X-ray diffraction analysis reveals that the nanoclays used to generate three series of modified TPEGs are generally swollen with copolymer and/or solvent. DA - 2005/3/29/ PY - 2005/3/29/ DO - 10.1021/la047837i VL - 21 IS - 7 SP - 3106-3115 SN - 0743-7463 ER - TY - JOUR TI - Outdiffusion of La and Al from amorphous LaAlO3 in direct contact with Si(001) AU - Sivasubramani, P AU - Kim, MJ AU - Gnade, BE AU - Wallace, RM AU - Edge, LF AU - Schlom, DG AU - Craft, HS AU - Maria, JP T2 - APPLIED PHYSICS LETTERS AB - We have evaluated the thermal stability of Al2O3/LaAlO3/Si (001) stacks with atomic force microscopy, x-ray diffraction, transmission electron microscopy, and secondary ion mass spectrometry using a back side polishing approach. Crystallization of the amorphous LaAlO3 film was found to occur for rapid thermal anneals (RTA) above 935 °C for 20 s, in flowing N2. Penetration of Al and La into the underlying Si (001) is clearly observed for RTA at or above 950 °C for 20 s in flowing N2. DA - 2005/5/16/ PY - 2005/5/16/ DO - 10.1063/1.1928316 VL - 86 IS - 20 SP - SN - 1077-3118 ER - TY - JOUR TI - On lattice and material-frame rotations and crystal hardening in high-symmetry axial loading AU - Havner, KS T2 - PHILOSOPHICAL MAGAZINE AB - A diverse range of experimental behaviour in high-symmetry tensile loading of fcc crystals has been reported in a number of classic papers in the literature (1960–1982). This behaviour includes: (i) axis stability and axisymmetric deformation in ⟨111⟩ and ⟨100⟩ load orientations; (ii) axis rotation toward a ⟨111⟩ orientation in coplanar double-slip in ⟨110⟩ loading; and (iii) axis rotations toward (from an initial misalignment) or away from precise ⟨111⟩ and ⟨100⟩ load orientations, with a reduced number of active slip planes. In this paper extensive kinematic analyses of coincident and relative rotations among material, lattice, and loading frames in each of these orientations, together with additional kinematic solutions for load-axis rotations, are combined with experimental information and perspectives connecting relative hardening and geometric slip-system interactions to determine probable active systems and slip rates in this diverse set of experiments. It is found that a set of basic hardening inequalities, which follow from classic latent hardening experiments in single slip, is consistent with the full range of experimental behaviour in high-symmetry axial-load orientations. DA - 2005/9/1/ PY - 2005/9/1/ DO - 10.1080/14786430500154315 VL - 85 IS - 25 SP - 2861-2894 SN - 1478-6435 ER - TY - JOUR TI - Nanoscience and technology: Firms take first steps AU - Bean, A. S. AU - Chapas, R. AU - Collins, M. J. AU - Kingon, A. I. T2 - Research Technology Management DA - 2005/// PY - 2005/// VL - 48 IS - 3 SP - 07- ER - TY - JOUR TI - Nanoelectromechanics of polarization switching in piezoresponse force microscopy AU - Kalinin, S. V. AU - Gruverman, A. AU - Rodriguez, B. J. AU - Shin, J. AU - Baddorf, A. P. AU - Karapetian, E. AU - Kachanov, M. T2 - Journal of Applied Physics DA - 2005/// PY - 2005/// VL - 97 IS - 7 ER - TY - JOUR TI - NO decomposition over a Pd/MgO catalyst prepared from [Pd(acac)(2)] AU - Wang, XQ AU - Spivey, JJ AU - Lamb, HH T2 - APPLIED CATALYSIS B-ENVIRONMENTAL AB - A Pd/MgO catalyst was prepared by adsorption of palladium bis-acetylacetonate [Pd(acac)2] onto highly dehydroxylated MgO from toluene solution and subsequent reduction in flowing H2 at 300 °C. The resultant catalyst was characterized by Pd K-edge X-ray absorption fine structure (XAFS) spectroscopy, temperature-programmed desorption (TPD), and Fourier transform infrared (FTIR) spectroscopy of adsorbed NO. The adsorbed [Pd(acac)2] species decomposes on heating in H2 to form 20–25 Å supported Pd particles; however, organic residues from the acetylacetonate ligands remain on the catalyst surface. The FTIR spectrum of NO adsorbed on the reduced Pd/MgO catalyst at 25 °C contains one principal band at 1722 cm−1 due to atop Pd nitrosyl species. In situ XAFS of the Pd/MgO catalyst indicates that neither Pd oxidation nor particle sintering occurs during heating in flowing 1% NO/He to 300 °C. NO decomposition over the Pd/MgO catalyst was investigated using temperature-programmed reaction spectroscopy (TPRS) and steady-state activity measurements. During the initial TPRS cycle in flowing 1% NO/He, nearly complete NO consumption occurs at ∼270 °C due to oxidation of organic residues. O2 evolution commences at approximately 350 °C, and steady-state catalytic decomposition of NO to N2 and O2 occurs at 600 °C. Transient NO consumption during rapid cooling in 1% NO/He (after steady-state catalysis) is attributed to NOx adsorption on the Pd/MgO catalyst. DA - 2005/4/8/ PY - 2005/4/8/ DO - 10.1016/j.apcatb.2004.09.014 VL - 56 IS - 4 SP - 261-268 SN - 1873-3883 KW - NO decomposition KW - temperature-programmed reaction KW - temperature-programmed desorption KW - X-ray absorption fine structure spectroscopy KW - Fourier transform infrared spectroscopy ER - TY - JOUR TI - Mechanobiology of mandibular distraction osteogenesis: finite element analyses with a rat model AU - Loboa, EG AU - Fang, TD AU - Parker, DW AU - Warren, SM AU - Fong, KD AU - Longaker, MT AU - Carter, DR T2 - JOURNAL OF ORTHOPAEDIC RESEARCH AB - Three-dimensional finite element (FE) analyses were performed to characterize the local mechanical environment created within the tissue regenerate during mandibular distraction osteogenesis (DO) in a rat model. Finite element models were created from three-dimensional computed tomography image data of rat hemi-mandibles at four different time points during an optimal distraction osteogenesis protocol (i.e., most successful protocol for bone formation): end latency (post-operative day (POD) 5), distraction day 2 (POD 7), distraction day 5 (POD 10), and distraction day 8 (POD 13). A 0.25 mm distraction was simulated and the resulting hydrostatic stresses and maximum principal tensile strains were determined within the tissue regenerate. When compared to previous histological findings, finite element analyses showed that tensile strains up to 13% corresponded to regions of new bone formation and regions of periosteal hydrostatic pressure with magnitudes less than 17 kPa corresponded to locations of cartilage formation. Tensile strains within the center of the gap were much higher, leading us to conclude that tissue damage would occur there if the tissue was not compliant enough to withstand such high strains, and that this damage would trigger formation of new mesenchymal tissue. These data were consistent with histological evidence showing mesenchymal tissue present in the center of the gap throughout distraction. Finite element analyses performed at different time points during distraction were instrumental in determining the changes in hydrostatic stress and tensile strain fields throughout distraction, providing a mechanical environment rationale for the different levels of bone formation in end latency, and distraction day 2, 5, and 8 specimens. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. DA - 2005/5// PY - 2005/5// DO - 10.1016/j.orthres.2004.09.010 VL - 23 IS - 3 SP - 663-670 SN - 1554-527X KW - mechanobiology KW - mandibular distraction osteogenesis KW - finite element analysis KW - computed tomography KW - mesenchymal tissue differentiation ER - TY - JOUR TI - Low-temperature reactive coupling at polymer-polymer interfaces facilitated by supercritical CO2 AU - Harton, SE AU - Stevie, FA AU - Spontak, RJ AU - Koga, T AU - Rafailovich, MH AU - Sokolov, JC AU - Ade, H T2 - POLYMER AB - Supercritical CO2 (scCO2) has been used to facilitate reactions in thin film bilayers between functionalized polystyrene and poly(methyl methacrylate) at temperatures far below the glass transition temperatures of the respective polymers. Secondary ion mass spectrometry (SIMS) is used to monitor the reaction progression directly by measuring the interfacial excess of deuterated PS. Complementary X-ray reflectometry (XR) yields the interfacial width and surface roughness of bilayer films for reactive systems with and without the addition of scCO2, and comparisons are made with unreactive reference systems. From XR and SIMS analyses, the interfacial width and roughness have been found to be effectively independent of the reaction conditions employed here, and the primary impact of incorporated scCO2 is enhanced mobility of the reactive polymer chains. The use of scCO2 can change polymer mobility significantly enough over a very small temperature range (DTw15 8C) so that both diffusion- and reaction-controlled type behavior can be observed for otherwise identical systems. q 2005 Elsevier Ltd. All rights reserved. DA - 2005/11/14/ PY - 2005/11/14/ DO - 10.1016/j.polymer.2005.07.085 VL - 46 IS - 23 SP - 10173-10179 SN - 1873-2291 KW - polymer bends KW - reactive compatibilization KW - supercritical fluids ER - TY - JOUR TI - Light emission, chip morphology, and burr formation in drilling the bulk metallic glass AU - Bakkal, M AU - Shih, AJ AU - McSpadden, SB AU - Liu, CT AU - Scattergood, RO T2 - INTERNATIONAL JOURNAL OF MACHINE TOOLS & MANUFACTURE AB - The chip light emission, chip morphology, burr formation and machined surface in drilling of Zr-based bulk metallic glass (BMG) material are investigated. This study demonstrates that the work- and tool-material as well as the feed rate and spindle speed, two drilling process parameters, all affect the onset of chip light emission. Slow feed rate and high spindle speed increase the specific cutting energy and promote the exothermic oxidation and light emission of the chip. Six types of chip morphology, powder, short ribbon, long ribbon, long spiral, long ribbon tangled, and fan, are observed in BMG drilling. The long ribbon tangled chip morphology is unique for BMG material. On the machined surface under quick stop condition, the fracture topography unique to metallic glass with tributary, void, and vein patterns is observed. Different burr formations are observed: the roll-over shape in the entry and the crown shape in the exit edge. The size of burr in the exit edge is typically larger than that in the entrance edge. High feed rate helps to reduce the size of burr in both entrance and exit edges. This study concludes that the WC–Co tool-material, due to its high thermal conductivity and hardness, performs better in drilling BMG than the high speed steel tool. DA - 2005/6// PY - 2005/6// DO - 10.1016/j.ijmachtools.2004.11.004 VL - 45 IS - 7-8 SP - 741-752 SN - 1879-2170 KW - bulk metallic glass KW - drilling KW - light emission KW - chip morphology KW - burr formation ER - TY - JOUR TI - Intrinsic band edge traps in nano-crystalline HfO2 gate dielectrics AU - Lucovsky, G AU - Zhang, Y AU - Luning, J AU - Afanase'v, , VV AU - Stesmans, A AU - Zollner, S AU - Triyoso, D AU - Rogers, BR AU - Whitten, JL T2 - MICROELECTRONIC ENGINEERING AB - Chemically pure thin films of HfO2, as well as other transition metal and rare earth elemental and complex oxides, e.g., LaScO3 and LaAlO3, are nanocrystalline as-deposited. The local bonding environments of the transition and rare earth atoms are distorted with respect to ideal octahedral or cubic bonding, and degeneracies of the respective band edge d-states are completely removed by Jahn-Teller (J-T) distortions. Spectroscopic studies have revealed these J-T term splittings, and also a band edge localized state which is assigned to an electronically-active bonding defect at nanocrystalline grain boundaries. DA - 2005/6// PY - 2005/6// DO - 10.1016/j.mee.2005.04.052 VL - 80 SP - 110-113 SN - 0167-9317 KW - conduction band states KW - Jahn-Teller term splittings KW - x-ray absorption spectroscopy KW - spectroscopic ellipsometry KW - photoconductivity KW - band edge traps ER - TY - JOUR TI - Influence of Zn doping profiles on excitation dependence of photoluminescence intensity in InGaAsP heterostructures AU - Young, DK AU - Reynolds, CL AU - Swarninathan, V AU - Walters, FS T2 - ELECTRONICS LETTERS AB - It is known that the Zn doping profile in strained multi-quantum-well (MQW) InGaAsP lasers strongly affects the electro-optical characteristics of these devices and their temperature sensitivity. A systematic investigation of the excitation dependence of the active layer photoluminescence (PL) intensity from compressively strained InGaAsP MQW pin laser material with different Zn doping profiles is described. When the pn junction lies within the active region, the excitation dependence of the PL intensity is superlinear at low excitation and linear at higher excitation. As the Zn profile is set back from the heterointerface creating a displaced pn junction from the active region, the excitation dependence is superlinear and linear at 300 K but becomes linear for all excitation powers at 77 K. The implications of these observations are discussed. DA - 2005/9/1/ PY - 2005/9/1/ DO - 10.1049/el:20052347 VL - 41 IS - 18 SP - 1008-1010 SN - 1350-911X ER - TY - JOUR TI - High negative ion yield from light molecule scattering AU - Scheer, JA AU - Wieser, M AU - Wurz, P AU - Bochsler, P AU - Hertzberg, E AU - Fuselier, SA AU - Koeck, FA AU - Nemanich, RJ AU - Schleberger, M T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS AB - Molecular oxygen and hydrogen ions were scattered at grazing incidence from several diamond-like carbon (DLC) surfaces in the energy range from 190 eV to 2400 eV. Most surfaces were hydrogen terminated. For incident positive oxygen ions, scattered negative ion fractions of up to 33% were recorded, and for incident positive hydrogen ions, negative ion fractions of more than 5% were measured. These values are among the highest ever reported, especially for oxygen. They have been matched only by results of scattering experiments using a hydrogen terminated surface of natural diamond. DA - 2005/4// PY - 2005/4// DO - 10.1016/j.nimb.2004.12.063 VL - 230 SP - 330-339 SN - 0168-583X KW - diamond like carbon (DLC) KW - neutral particle imaging KW - particle scattering KW - surface ionization KW - tetrahedral amorphous carbon KW - ta-C ER - TY - JOUR TI - Epitaxial growth of zinc oxide thin films on silicon AU - Jin, Chunming AU - Narayan, Roger AU - Tiwari, Ashutosh AU - Zhou, Honghui AU - Kvit, Alex AU - Narayan, Jagdish T2 - Materials Science and Engineering: B AB - Epitaxial zinc oxide thin films were grown on Si(1 1 1) using aluminum nitride and magnesium oxide/titanium nitride buffer layers. The resultant films were examined using transmission electron microscopy, X-ray diffraction, electrical conductivity, and photoluminescence spectroscopy. The following epitaxial relationships were observed in the ZnO/AlN/Si(1 1 1) heterostructure: ZnO[0 0 0 1] || AlN[0 0 0 1] || Si[1 1 1] along the growth direction, and ZnO[21¯1¯0] || AlN[21¯1¯0] || Si[011¯] along the in-plane direction. Domain-matching epitaxial growth of TiN on Si(1 1 1) substrate allows successful epitaxial growth of MgO and ZnO layers in a ZnO/MgO/TiN/Si(1 1 1) heterostructure. The epitaxial relationships observed for this heterostructure were ZnO[0 0 0 1] || MgO/TiN/Si[1 1 1] along the growth direction and ZnO[21¯1¯0] || MgO/TiN/Si[011¯] along in-plane direction. The resultant ZnO films demonstrate excellent electrical and optical properties. ZnO thin films exhibit extremely bright ultraviolet luminescence with relatively weak green-band emission. DA - 2005/3// PY - 2005/3// DO - 10.1016/j.mseb.2004.12.003 VL - 117 IS - 3 SP - 348-354 J2 - Materials Science and Engineering: B LA - en OP - SN - 0921-5107 UR - http://dx.doi.org/10.1016/j.mseb.2004.12.003 DB - Crossref KW - Pulsed laser deposition KW - epitaxy of thin films KW - zinc oxide ER - TY - JOUR TI - Enhanced photoconductivity of ZnO films Co-doped with nitrogen and tellurium AU - Porter, H. L. AU - Cai, A. L. AU - Muth, J. F. AU - Narayan, J. T2 - Applied Physics Letters AB - Zinc oxide films are typically found to be n type, and conductive under most growth conditions and growth methods. Co-doping with multiple elements is one strategy for improving the electrical and optical properties of zinc oxide materials for optoelectronic device applications. Using pulsed-laser deposition, thin ZnO films were grown on c-axis oriented sapphire. The films were co-doped with nitrogen and tellurium. Depending on the relative concentrations of the dopants, the resistivity of the films was observed to increase by several orders of magnitude, significantly improving the photoconductive response. The enhancement of the photosensitivity reached a maximum at a tellurium concentration of around 1020cm−3. DA - 2005/5/23/ PY - 2005/5/23/ DO - 10.1063/1.1923194 VL - 86 IS - 21 SP - 211918 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.1923194 DB - Crossref ER - TY - JOUR TI - Effect of doping on the magnetic properties of GaMnN: Fermi level engineering AU - Reed, MJ AU - Arkun, FE AU - Berkman, EA AU - Elmasry, NA AU - Zavada, J AU - Luen, MO AU - Reed, ML AU - Bedair, SM T2 - APPLIED PHYSICS LETTERS AB - GaMnN dilute magnetic semiconductor samples, prepared by metalorganic chemical vapor deposition, are shown to exhibit ferromagnetism or even paramagnetism depending upon the type and concentration of extrinsic impurity present in the film. In addition, GaMnN deposited using growth parameters normally yielding a nonferromagnetic film becomes strongly ferromagnetic with the addition of magnesium, an acceptor dopant. Based upon these observations, it seems that ferromagnetism in this material system depends on the relative position of the Mn energy band and the Fermi level within the GaMnN band gap. Only when the Fermi level closely coincides with the Mn-energy level is ferromagnetism achieved. By actively engineering the Fermi energy to be within or near the Mn energy band, room temperature ferromagnetism is realized. DA - 2005/3/7/ PY - 2005/3/7/ DO - 10.1063/1.1881786 VL - 86 IS - 10 SP - SN - 1077-3118 ER - TY - CONF TI - EBIC study of electrical activity of stacking faults in multicrystalline sheet silicon AU - Lu, J. G. AU - Rozgonyi, G. AU - Rand, J. AU - Jonczyk, R. C2 - 2005/// C3 - Proceedings of the 9th International Autumn Meeting: Gettering and defect engineering in semiconductor technology: GADEST 2001, S. Tecla, Italy, September 30-October 3, 2001 (Solid state phenomena) CN - TK7871.85 .I574 2001 [Hill & Electronic Resource] DA - 2005/// VL - 108-109 SP - 627-630 PB - Uetikon-Zurich, Switzerland: Sci-Tech Pub. Ltd.; Enfield, N.H.: Trans Tech Pub. Ltd. SN - 3908450640 ER - TY - JOUR TI - Direct imaging of quantum antidots in MgO dispersed with Au nanoclusters AU - Wang, C. M. AU - Shutthanandan, V. AU - Thevuthasan, S. AU - Duscher, G. T2 - Applied Physics Letters DA - 2005/// PY - 2005/// VL - 87 IS - 15 SP - 153104 ER - TY - JOUR TI - Dipole-radiation model for terahertz radiation from semiconductors AU - Peng, HJ AU - Aspnes, DE T2 - APPLIED PHYSICS LETTERS AB - We present a simple dipole-radiation model for the generation of terahertz radiation from semiconductors under short-pulse excitation. Using a one-dimensional force model applied to bond charges and free carriers, we evaluate both current-surge and frequency-mixing contributions to obtain analytic expressions that provide an integrated description of previous results. DA - 2005/5/23/ PY - 2005/5/23/ DO - 10.1063/1.1937992 VL - 86 IS - 21 SP - SN - 0003-6951 ER - TY - JOUR TI - Conduction band-edge states associated with the removal of d-state degeneracies by the Jahn-Teller effect AU - Lucovsky, G AU - Fulton, CC AU - Zhang, Y AU - Zou, Y AU - Luning, J AU - Edge, LF AU - Whitten, JL AU - Nemanich, RJ AU - Ade, H AU - Schlom, DG AU - Afanase'v, , VV AU - Stesmans, A AU - Zollner, S AU - Triyoso, D AU - Rogers, BR T2 - IEEE TRANSACTIONS ON DEVICE AND MATERIALS RELIABILITY AB - X-ray absorption spectroscopy (XAS) is used to study band edge electronic structure of high-/spl kappa/ transition metal (TM) and trivalent lanthanide rare earth (RE) oxide gate dielectrics. The lowest conduction band d/sup */-states in TiO/sub 2/, ZrO/sub 2/ and HfO/sub 2/ are correlated with: 1) features in the O K/sub 1/ edge, and 2) transitions from occupied Ti 2p, Zr 3p and Hf 4p states to empty Ti 3d-, Zr 4d-, and Hf 5d-states, respectively. The relative energies of d-state features indicate that the respective optical bandgaps, E/sub opt/ (or equivalently, E/sub g/), and conduction band offset energy with respect to Si, E/sub B/, scale monotonically with the d-state energies of the TM/RE atoms. The multiplicity of d-state features in the Ti L/sub 2,3/ spectrum of TiO/sub 2/, and in the derivative of the O K/sub 1/ spectra for ZrO/sub 2/ and HfO/sub 2/ indicate a removal of d-state degeneracies that results from a static Jahn-Teller effect in these nanocrystalline thin film oxides. Similar removals of d-state degeneracies are demonstrated for complex TM/RE oxides including Zr and Hf titanates, and La, Gd and Dy scandates. Analysis of XAS and band edge spectra indicate an additional band edge state that is assigned Jahn-Teller distortions at internal grain boundaries. These band edges defect states are electronically active in photoconductivity (PC), internal photoemission (IPE), and act as bulk traps in metal oxide semiconductor (MOS) devices, contributing to asymmetries in tunneling and Frenkel-Poole transport that have important consequences for performance and reliability in advanced Si devices. DA - 2005/3// PY - 2005/3// DO - 10.1109/TDMR.2005.845804 VL - 5 IS - 1 SP - 65-83 SN - 1558-2574 KW - complex oxides KW - conduction band edge states KW - d-state degeneracy KW - high-k dielectrics KW - Jahn-Teller splittings KW - photoconductivity KW - spectroscopic ellipsometry KW - x-ray absorption spectroscopy ER - TY - JOUR TI - Capacitive response of doped CuO/ZnO heterocontacts to hydrogen AU - Kwon, S. AU - Aygun, S. AU - Cann, D. P. T2 - Sensor Letters DA - 2005/// PY - 2005/// VL - 3 IS - 3 SP - 258-262 ER - TY - JOUR TI - Ball indentation tests for a Zr-based bulk metallic glass AU - Trichy, GR AU - Scattergood, RO AU - Koch, CC AU - Murty, KL T2 - SCRIPTA MATERIALIA AB - Zr52.5Ti5Cu17.9Ni14.6Al10 bulk metallic glass was characterized using ball indentation tests. Comparison of the data with the expanding cavity model revealed that the deformation is pressure insensitive for compressive loading. The plastic flow curves obtained from indentation tests showed perfectly plastic response and no strain rate sensitivity up to 15% strain. DA - 2005/12// PY - 2005/12// DO - 10.1016/j.scriptamat.2005.08.010 VL - 53 IS - 12 SP - 1461-1465 SN - 1872-8456 KW - ball indentation tests KW - bulk metallic glass KW - pressure sensitivity KW - strain rate sensitivity ER - TY - JOUR TI - Sulfur doped nanocrystalline diamond films as field enhancement based thermionic emitters and their role in energy conversion AU - Koeck, FAM AU - Nemanich, RJ T2 - DIAMOND AND RELATED MATERIALS AB - Sulfur doped nanocrystalline diamond films, like other nanostructured carbon films, exhibit electron emission characterized by a spatial non-uniformity of the field enhancement factor. While field emission effects are observed at room temperature, an increase in emitter temperature is accompanied by an amplified emission current with a simultaneous drop in the threshold field. At low extraction fields a fit of the emission current to the Richardson equation indicates a material work function of ∼2.5 eV. The Schottky formula describes thermionic emission at a moderate field and is utilized to determine the work function at an electric field of 0.8 V/μm with a value of ∼1.7 eV and a concurrently reduced Richardson constant. This significant difference in the work function of 2.5 and 1.7 eV for 0.5 and 0.8V/μm, respectively can be attributed to field enhancement effects. DA - 2005/// PY - 2005/// DO - 10.1016/j.diamond.2005.09.001 VL - 14 IS - 11-12 SP - 2051-2054 SN - 0925-9635 KW - doped nanocrystalline diamond KW - thermionic emission KW - field emission KW - energy conversion KW - CVD ER - TY - JOUR TI - Scanning probe investigation of surface charge and surface potential of GaN-based heterostructures AU - Rodriguez, BJ AU - Yang, WC AU - Nemanich, RJ AU - Gruverman, A T2 - APPLIED PHYSICS LETTERS AB - Scanning Kelvin probe microscopy (SKPM) and electrostatic force microscopy (EFM) have been employed to measure the surface potentials and the surface charge densities of the Ga- and the N-face of a GaN lateral polarity heterostructure (LPH). The surface was subjected to an HCl surface treatment to address the role of adsorbed charge on polarization screening. It has been found that while the Ga-face surface appears to be unaffected by the surface treatment, the N-face surface exhibited an increase in adsorbed screening charge density (1.6±0.5×1010cm−2), and a reduction of 0.3±0.1V in the surface potential difference between the N- and Ga-face surfaces. DA - 2005/3/14/ PY - 2005/3/14/ DO - 10.1063/1.1869535 VL - 86 IS - 11 SP - SN - 1077-3118 ER - TY - JOUR TI - Real-time diagnostics for metalorganic vapor phase epitaxy AU - Aspnes, DE T2 - PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS AB - Abstract Metalorganic vapor phase epitaxy is a complicated process whereby constituents of incoming reactant species are incorporated into the growing crystal through a number of stages. A range of optical probes has been developed to provide detailed information about these stages and the sample as growth proceeds. While many of these probes are mature, spectroscopic ellipsometry (SE) and polarimetry (SP) are both undergoing rapid improvements as a result of applications in integrated‐circuits technology. Here, I review some of these advances and the motivation behind them, and illustrate capabilities with an application regarding the heteroepitaxial growth of GaSb on GaAs. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) DA - 2005/11// PY - 2005/11// DO - 10.1002/pssb.200541109 VL - 242 IS - 13 SP - 2551-2560 SN - 0370-1972 ER - TY - JOUR TI - Preparation of sputtered (Ba-x,Sr1-x)TiO3 thin films directly on copper AU - Laughlin, B AU - Ihlefeld, J AU - Maria, JP T2 - JOURNAL OF THE AMERICAN CERAMIC SOCIETY AB - (Ba 0.6 ,Sr 0.4 )TiO 3 (BST) films were deposited on copper foils by radio frequency magnetron sputtering. By the use of controlled p O 2 high‐temperature anneals, the films were completely crystallized in the absence of substrate oxidation. X‐ray diffraction and transmission electron microscopy (TEM) revealed an abrupt Cu/BST interface. The deposited BST films exhibit a zero bias permittivity and loss tangent values of 600 and 0.018, respectively. An electrical tunability ratio of 3.5:1 is observed on these metal–insulator–metal devices. Devices show leakage currents of 10 −8 A/cm 2 at ±10 V/μm, and loss tangents as low as 0.003 in fields approaching 40 V/μm. DA - 2005/9// PY - 2005/9// DO - 10.1111/j.1551-2916.2005.00488.x VL - 88 IS - 9 SP - 2652-2654 SN - 1551-2916 ER - TY - JOUR TI - Large negative magnetoresistance of the rare-earth transition-metal intermetallic compound PrMnSi2 AU - Kim, SH AU - Seo, DK AU - Kremer, RK AU - Kohler, M AU - Villesuzanne, A AU - Whangbo, MH T2 - CHEMISTRY OF MATERIALS AB - The rare-earth intermetallic compound PrMnSi2 consists of two magnetic sublattices, i.e., layers of Mn atoms and layers of Pr atoms, which repeat in the (−Mn−Pr−Pr−)∞ sequence. Electrical resistivity measurements were carried out for PrMnSi2 between 2 and 350 K under various magnetic fields. PrMnSi2 is a metal with two metal-to-metal transitions at ∼20 and ∼50 K, and its resistivity vs temperature curves show a significant hysteresis in the absence and presence of an external magnetic field. The resistivity is reduced by an external magnetic field, and this negative magnetoresistance reaches up to 47% at 9 T around 17 K where PrMnSi2 is antiferromagnetic at zero field. The magnetoresistance vs temperature curves of PrMnSi2 reveal three peaks at fields up to ∼3 T, which correspond to the three magnetic phase transitions of PrMnSi2 observed from magnetic susceptibility and heat capacity measurements. The negative magnetoresistance and the resistivity hysteresis of PrMnSi2 were accounted for by considering how the scattering of the electrons at the Fermi level is reduced by an applied field. DA - 2005/12/13/ PY - 2005/12/13/ DO - 10.1021/cm051669d VL - 17 IS - 25 SP - 6338-6341 SN - 0897-4756 ER - TY - JOUR TI - Grain size softening in nanocrystalline TiN AU - Conrad, H AU - Narayan, J AU - Jung, K T2 - INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS AB - The effect of grain size d on the hardness H of TiN is considered, with focus on the nanometer grain size range. H increases from ∼22 GPa to ∼32 GPa with decrease in d from single crystals to d = 50 nm. Three sets of data show that H decreases with further reduction in d below 50 nm, i.e., grain size softening occurs. The softening is not in complete or unequivocal accord with any of the three models normally proposed for such softening, namely Coble creep, grain boundary shear and dislocation line tension modification. Factors which could have contributed to the softening are: (a) changes in texture and in turn the corresponding value of the Taylor orientation factor M and (b) the presence of weakening imperfections produced during fabrication. DA - 2005/// PY - 2005/// DO - 10.1016/j.ijrmhm.2005.04.016 VL - 23 IS - 4-6 SP - 301-305 SN - 0263-4368 KW - TiN KW - nanocrystalline KW - grain size KW - hardness KW - grain size softening KW - texture ER - TY - JOUR TI - Effect of grain size from mm to nm on the flow stress and plastic deformation kinetics of Au at low homologous temperatures AU - Conrad, H AU - Jung, K T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING AB - Three grain size regimes were identified: Regime I (d > ∼0.5 μm), Regime II (d ≈ 10–500 nm) and Regime III (d < ∼10 nm). Grain size hardening in accord with the Hall–Petch (H–P) equation occurred in Regimes I and II, grain size softening with the flow stress proportional to d−1 occurred in III. The rate-controlling mechanism in Regime I was concluded to be the intersection of dislocations, that in II grain boundary shear promoted by the pile-up of dislocations and that in III grain boundary shear without pile-ups. The transition from I to II occurred when the dislocation cell size became larger than the grain size, that from II to III when the dislocation elastic interaction spacing became larger than the grain size. The H–P behavior in Regime I is in accord with the dislocation density model, that in II with the dislocation pile-up model. The general behavior of Au is similar to that reported previously for Cu and Ag. DA - 2005/10/15/ PY - 2005/10/15/ DO - 10.1016/j.msea.2005.06.051 VL - 406 IS - 1-2 SP - 78-85 SN - 1873-4936 KW - gold KW - grain size KW - Hall-Petch KW - rate-controlling mechanism KW - grain boundary shear ER - TY - JOUR TI - Effect of carrier blocking layers on the emission characteristics of AlGaN-based ultraviolet light emitting diodes AU - Park, JS AU - Fothergill, DW AU - Zhang, XY AU - Reitmeier, ZJ AU - Muth, JF AU - Davis, RF T2 - JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS AB - AlGaN-based thin film heterostructures suitable for ultraviolet light emitting diodes have been grown and fabricated into working devices with and without p-type and n-type AlGaN carrier-blocking layers at the top and the bottom of the quantum wells, respectively. The principal emission from each device occurred at 353 nm. The highest intensities of this peak were measured at all values of the injection current in the device with a p-type carrier-blocking layer at the top of the quantum well; this device also exhibited the highest values of light output power. Growth of an n-type carrier-blocking layer at the bottom of the quantum wells had an adverse effect on the light emitting diode characteristics. A broad peak centered at ∼540 nm exhibited yellow luminescence and was present in the spectra acquired from all the devices. This peak is attributed to absorption of the UV emission by and re-emission from the p-GaN and/or to the luminescence from the AlGaN within quantum wells by current injection. The intensity of this peak increased and saturated by the same order of magnitude as the intensity of the UV emission at 353 nm. DA - 2005/10// PY - 2005/10// DO - 10.1143/jjap.44.7254 VL - 44 IS - 10 SP - 7254-7259 SN - 0021-4922 KW - light emitting diode KW - ultraviolet KW - AlGaN KW - carrier blocking layer KW - quantum well ER - TY - JOUR TI - Effect of beta-sheet crystals on the thermal and rheological behavior of protein-based hydrogels derived from gelatin and silk fibroin AU - Gil, ES AU - Spontak, RJ AU - Hudson, SM T2 - MACROMOLECULAR BIOSCIENCE AB - Novel protein-based hydrogels have been prepared by blending gelatin (G) with amorphous Bombyx mori silk fibroin (SF) and subsequently promoting the formation of beta-sheet crystals in SF upon exposure to methanol or methanol/water solutions. Differential scanning calorimetry of the resultant hydrogels confirms the presence and thermoreversibility of the G helix-coil transition between ambient and body temperature at high G concentrations. At low G concentrations, this transition is shifted to higher temperatures and becomes progressively less pronounced. Complementary dynamic rheological measurements reveal solid-liquid cross-over at the G helix-coil transition temperature typically between 30 and 36 degrees C in blends prior to the formation of beta-sheet crystals. Introducing the beta-sheet conformation in SF stabilizes the hydrogel network and extends the solid-like behavior of the hydrogels to elevated temperatures beyond body temperature with as little as 10 wt.-% SF. The temperature-dependent elastic modulus across the G helix-coil transition is reversible, indicating that the conformational change in G can be used in stabilized G/SF hydrogels to induce thermally triggered encapsulant release. DA - 2005/8/12/ PY - 2005/8/12/ DO - 10.1002/mabi.200500076 VL - 5 IS - 8 SP - 702-709 SN - 1616-5187 KW - gelatin KW - helix-coil transition KW - hydrogels KW - polymer network KW - silk fibroin ER - TY - JOUR TI - Conduction band states of transition metal (TM) high-k gate dielectrics as determined from X-ray absorption spectra AU - Lucovsky, G AU - Hong, JG AU - Fulton, CC AU - Stoute, NA AU - Zou, Y AU - Nemanich, RJ AU - Aspnes, DE AU - Ade, H AU - Schlom, DG T2 - MICROELECTRONICS RELIABILITY AB - This paper uses X-ray absorption spectroscopy to study the electronic structure of the high-k gate dielectrics including TM and RE oxides. The results are applicable to TM and rare earth (RE) silicate and aluminate alloys, as well as complex oxides comprised of mixed TM/TM and TM/RE oxides. These studies identify the nature of the lowest conduction band d∗ states, which define the optical band gap, Eg, and the conduction band offset energy with respect to crystalline Si, EB. Eg and EB scale with the atomic properties of the TM and RE atoms providing important insights for identification high-k dielectrics that meet performance targets for advanced CMOS devices. DA - 2005/// PY - 2005/// DO - 10.1016/j.microrel.2004.11.038 VL - 45 IS - 5-6 SP - 827-830 SN - 0026-2714 ER - TY - JOUR TI - Characterization of remote inductively coupled CH4-N-2 plasma for carbon nitride thin-film deposition AU - Seo, H. AU - Kim, J. H. AU - Chung, K. H. AU - Kim, J. Y. AU - Kim, S. H. AU - Jeon, H. T2 - Journal of Applied Physics DA - 2005/// PY - 2005/// VL - 98 IS - 4 ER - TY - JOUR TI - A printable form of single-crystalline gallium nitride for flexible optoelectronic systems AU - Lee, K. J. AU - Lee, J. AU - Hwang, H. D. AU - Reitmeier, Z. J. AU - Davis, R. F. AU - Rogers, J. A. AU - Nuzzo, R. G. T2 - Small (Weinheim An Der Bergstrasse, Germany) DA - 2005/// PY - 2005/// VL - 1 IS - 12 SP - 1164-1168 ER - TY - JOUR TI - Void formation during early stages of passivation: Initial oxidation of iron nanoparticles at room temperature AU - Wang, C. M. AU - Baer, D. R. AU - Thomas, L. E. AU - Amonette, J. E. AU - Antony, J. AU - Qiang, Y. AU - Duscher, G. T2 - Journal of Applied Physics DA - 2005/// PY - 2005/// VL - 98 IS - 9 ER - TY - JOUR TI - Ultraviolet-illumination-enhanced photoluminescence effect in zinc oxide thin films AU - Jin, CM AU - Tiwari, A AU - Narayan, RJ T2 - JOURNAL OF APPLIED PHYSICS AB - We report an enhancement effect of ultraviolet illumination on the photoluminescence intensities of zinc oxide thin films. Large-grain ⟨0001⟩-textured zinc oxide thin films were deposited on amorphous-fused silica substrates using pulsed laser deposition. We found that the intensities of excitonic emission and green-band emission increased with ultraviolet light exposure time until a maximum value was achieved. We attribute this ultraviolet radiation enhancement effect to oxygen desorption on the surface of the zinc oxide thin film. We have proposed a phenomenological model to explain this interesting photoluminescence behavior. DA - 2005/10/15/ PY - 2005/10/15/ DO - 10.1063/1.2108156 VL - 98 IS - 8 SP - SN - 1089-7550 ER - TY - JOUR TI - Ultrahigh strength and high ductility of bulk nanocrystalline copper AU - Youssef, KM AU - Scattergood, RO AU - Murty, KL AU - Horton, JA AU - Koch, CC T2 - APPLIED PHYSICS LETTERS AB - We have synthesized artifact-free bulk nanocrystalline copper samples with a narrow grain size distribution (mean grain size of 23nm) that exhibited tensile yield strength about 11 times higher than that of conventional coarse-grained copper, while retaining a 14% uniform tensile elongation. In situ dynamic straining transmission electron microscope observations of the nanocrystalline copper are also reported, which showed individual dislocation motion and dislocation pile-ups. This suggests a dislocation-controlled deformation mechanism that allows for the high strain hardening observed. Trapped dislocations are observed in the individual nanograins. DA - 2005/8/29/ PY - 2005/8/29/ DO - 10.1063/1.2034122 VL - 87 IS - 9 SP - SN - 1077-3118 ER - TY - JOUR TI - Thermionic field emission from nanocrystalline diamond-coated silicon tip arrays AU - Garguilo, JM AU - Koeck, FAM AU - Nemanich, RJ AU - Xiao, XC AU - Carlisle, JA AU - Auciello, O T2 - PHYSICAL REVIEW B AB - Thermionic field emission properties of nitrogen doped ultrananocrystalline diamond (UNCD) coated silicon tip arrays are examined using thermionic field emission electron microscopy (TFEEM). Nitrogen doping has been shown to enhance the emission properties of diamond by the introduction of a donor level $1.7\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ below the conduction band minimum. The field enhancing geometry of the films initiates accelerated electron emission at the tipped structures which may be beneficial to thermionic energy converter design where space charge effects can significantly limit attainable current densities. Two temperature regimes of electron emission are observed; $600--800\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$, where the emission is enabled because of the H passivation and $900--1100\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$, where the emission is attributed to tunneling from nitrogen related states through the barrier of a clean diamond surface. DA - 2005/10// PY - 2005/10// DO - 10.1103/physrevb.72.165404 VL - 72 IS - 16 SP - SN - 2469-9969 ER - TY - JOUR TI - Swelling behavior and morphological evolution of mixed gelatin/silk fibroin hydrogels AU - Gil, ES AU - Frankowski, DJ AU - Spontak, RJ AU - Hudson, SM T2 - BIOMACROMOLECULES AB - Mixed protein-based hydrogels have been prepared by blending gelatin (G) with amorphous Bombyx mori silk fibroin (SF) and promoting β-crystallization of SF via subsequent exposure to methanol or methanol/water solutions. The introduction of β crystals in SF serves to stabilize the hydrogel network and extend the solidlike behavior of these thermally responsive materials to elevated temperatures beyond the helix→coil (h→c) transition of G. In this work, we investigate the swelling and protein release kinetics of G/SF hydrogels varying in composition at temperatures below and above the G h→c transition. At 20 °C, G and G-rich mixed hydrogels display evidence of moderate swelling with negligible mass loss in aqueous solution, resulting in porous polymer matrixes upon solvent removal according to electron microscopy. When the solution temperature is increased beyond the G h→c transition to body temperature (37 °C), these gels exhibit much higher swelling with considerable mass loss due to dissolution and release of G. The extent to which these properties respond to temperature decreases systematically with increasing SF content. The unique temperature- and composition-dependent properties of G/SF hydrogels dictate the efficacy of these novel materials as stimuli-responsive delivery vehicles. DA - 2005/// PY - 2005/// DO - 10.1021/bm050396c VL - 6 IS - 6 SP - 3079-3087 SN - 1526-4602 ER - TY - JOUR TI - Processing TiPdNi base thin-film shape memory alloys using ion beam assisted deposition AU - Baldwin, E AU - Thomas, B AU - Lee, JW AU - Rabiei, A T2 - SURFACE & COATINGS TECHNOLOGY AB - A new generation of thin-film shape memory alloys (SMA) has been developed with less than 2 μm thickness for MEMS microactuator applications. In this study, thin-film TiPdNi SMA was processed using ion beam assisted deposition (IBAD) with and without in situ heat treatment. As-deposited films were found to be amorphous. Postdeposition annealing lead to bulk diffusion of palladium to the substrate interface and silicon into the bulk film, creating a porous cross section. Various forms of tensile failures were observed including decohesion and delamination as a result of postdeposition annealing. Effect of heating and cooling rates was studied as well as in situ heat treatment during deposition. Deposition using the IBAD technique with in situ heat treatment was successful in producing fully martensitic films 1.5 μm thick and with reduced grain size and film defects, compared to the other sputter deposited films and IBAD deposited followed by postdeposition heat treatment. The effects of various processing parameters, and heat treatment conditions, on film properties have been studied. DA - 2005/12/21/ PY - 2005/12/21/ DO - 10.1016/j.surfcoat.2004.08.172 VL - 200 IS - 7 SP - 2571-2579 SN - 0257-8972 KW - shape memory alloy KW - ion beam assisted deposition KW - thin film KW - TiPdNi KW - heat treatment ER - TY - JOUR TI - Investigation of blend miscibility of a ternary PS/PCHMA/PMMA system using SIMS and mean-field theory AU - Harton, SE AU - Koga, T AU - Stevie, FA AU - Araki, T AU - Ade, H T2 - MACROMOLECULES AB - Poly(cyclohexyl methacrylate) (PCHMA) and polystyrene (PS) are miscible with each other, but each is highly immiscible with PMMA. Identifiable by the asymmetries in the binary mean-field interaction parameters χ, PS preferentially segregates to the PCHMA/PMMA interface. Secondary ion mass spectrometry was used to provide real-space depth profiles of deuterated PS (dPS) in a miscible blend with PCHMA. The initial dPS concentration was varied from 5 to 20% (v/v), and the blend film was annealed at 150 °C on a film of PMMA for 42 h. X-ray reflectometry was used to determine the interfacial width between PCHMA and PMMA at 150 °C. Using self-consistent mean-field theory, good agreement was found between the experimental and theoretical interfacial excess Z* of dPS at each concentration. Because of their similar glass transition temperatures (∼100 °C for PS and PCHMA) and the ability of PS and PCHMA to be controllably synthesized with low polydispersities, we anticipate this blend to be a model system for future investigations of such phenomena as diffusion in miscible blends and diffusion near surfaces and interfaces. DA - 2005/12/13/ PY - 2005/12/13/ DO - 10.1021/ma051595r VL - 38 IS - 25 SP - 10511-10515 SN - 1520-5835 ER - TY - JOUR TI - In-situ infrared spectroscopy and density functional theory modeling of hafnium alkylamine adsorption on Si-OH and Si-H surfaces AU - Kelly, MJ AU - Han, JH AU - Musgrave, CB AU - Parsons, GN T2 - CHEMISTRY OF MATERIALS AB - In-situ attenuated total internal reflection infrared spectroscopy has been used to examine initial adsorption and reaction steps in atomic layer deposition of HfO2 from tetrakis(diethylamino) hafnium (TDEAHf) on SiO2 and hydrogen-terminated Si(100) surfaces. At low deposition temperatures (25−250 °C), TDEAHf directly reacts with the Si−H surface, resulting in partial removal of Si−H bonds and formation of a four-membered Si−O−Hf−Si bonding structure that can rapidly oxidize. The hydrogen removal process is observed to continue through many cycles of TDEAHf/H2O exposure, signifying continued reactivity of the Hf precursor with the silicon surface. Density functional theory calculations have been performed for various reactions between tetrakis(dimethylamino) hafnium and Si−H surfaces, and several possible reaction pathways for hydrogen removal have been identified and analyzed. The calculations suggest that hydrogen removal proceeds by H abstraction by an amine ligand of the Hf precursor and that the abstraction reaction is made more facile by the presence of OH on the otherwise H-terminated Si surface. DA - 2005/10/18/ PY - 2005/10/18/ DO - 10.1021/cm051064h VL - 17 IS - 21 SP - 5305-5314 SN - 1520-5002 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000232743700015&KeyUID=WOS:000232743700015 ER - TY - JOUR TI - Electrochemical preparation of a stable accumulation layer on Si: A synchrotron radiation photoelectron spectroscopy study AU - Skorupska, K AU - Lublow, M AU - Kanis, M AU - Jungblut, H AU - Lewerenz, HJ T2 - APPLIED PHYSICS LETTERS AB - Chronoamperometric conditioning of float zone n-Si(111) in 2M NaOH solution in the potential range negative from open-circuit potential is performed in a combined electrochemistry/ultrahigh-vacuum surface analysis experiment. Synchrotron Radiation Photoelectron Spectroscopy measurements at the U49/2 beamline at Bessy II using the SoLiAs facility show formation of a ultrahigh-vacuum-stable permanent accumulation layer without junction formation. Comparison of the Thomas–Fermi screening potential and the mean inelastic scattering length λesc of photoelectrons at hν=150eV (λesc=4Å) and hν=585eV (λesc=15Å) indicates a surface electron concentration of 3×1018cm−3 for a bulk doping level of 1015cm−3. The observed shift of the Si2p3∕2 and 2p1∕2 core level with photon energy is in excellent agreement with the shifted onset of the x-ray photoelectron spectroscopy valence-band spectrum measured at hν=150eV. DA - 2005/12/26/ PY - 2005/12/26/ DO - 10.1063/1.2150267 VL - 87 IS - 26 SP - SN - 1077-3118 ER - TY - CHAP TI - Effect of annealing temperature on texture and creep anisotropy in Ti3Al2.5V alloy AU - Murty, K. L. AU - Kishore, R. AU - Yan, J. AU - Scattergood, R. O. AU - Helsel, A. W. T2 - Textures of materials: ICOTOM 14: Proceedings of the 14th International Conference on Textures of Materials, held in Leuven, Belgium, July 11-15, 2005 / Paul van Houtte; Leo Kestens. Uetikon-Zuerich, Switzerland ; Enfield, NH: Trans Tech Publications, 2005. (Materials science forum ; 495-497) AB - Effect of annealing temperature is investigated on texture and creep anisotropy in a thinwalled tubing of titanium alloy. Creep anisotropy is studied under equibiaxial loading using internally pressurized tubing superimposed with axial load while monitoring in-situ the time variations of both hoop and axial strains. Relatively weak hoop direction in the cold-worked material became stronger following complete recrystallization. The analyses of the data reveal that the anisotropy parameter, P which is the contractile strain ratio for testing along hoop direction increases from around 0.6 for the cold-worked material to around 1.5 following complete recrystallization. Results indicate that planar isotropy should occur following annealing at around 800K. Work on the effects of annealing on the textures and deformation microstructures is in progress. We summarize here results from some of our earlier work on a different lot of Ti3Al2.5V tubing in the recrystallized states where the ODFs were used in conjunction with crystal slip models to predict creep anisotropy. CN - [Not currently held by TRLN member libraries.] PY - 2005/// DO - 10.4028/www.scientific.net/msf.495-497.1645 VL - 495-497 SP - 1645-1650 PB - Utikon-Zurich, Switzerland: Trans Tech Publications ER - TY - JOUR TI - Dielectric functions of AlxGa1-xSb (0.00 <= x <= 0.39) alloys from 1.5 to 6.0 eV AU - Choi, SG AU - Palmstrom, CJ AU - Kim, YD AU - Cooper, SL AU - Aspnes, DE T2 - JOURNAL OF APPLIED PHYSICS AB - Room-temperature pseudodielectric function spectra ⟨ε(ω)⟩=⟨ε1(ω)⟩+i⟨ε2(ω)⟩ of AlxGa1−xSb (0.00⩽x⩽0.39) alloys were measured from 1.5to6.0eV by spectroscopic ellipsometry. Effects of surface overlayers on the measured spectra have been minimized as far as possible by performing in situ chemical etching on samples immediately before the measurements rather than correcting the measured data mathematically for the presence of overlayers. Analysis of second energy derivatives numerically calculated from the measured data yielded the critical-point energies of the E1, E1+Δ1, E0′, E2, and E1′ interband transitions. Dependence of the critical-point energies on composition x is obtained. DA - 2005/11/15/ PY - 2005/11/15/ DO - 10.1063/1.2134890 VL - 98 IS - 10 SP - SN - 1089-7550 ER - TY - JOUR TI - Defects and defect relaxation at internal interfaces between high-k transition metal and rare earth dielectrics and interfacial native oxides in metal oxide semiconductor (MOS) structures AU - Lucovsky, G AU - Phillips, JC T2 - THIN SOLID FILMS AB - Composite gate dielectrics for advanced Si devices that include high-k dielectrics have two interfaces that determine performance and reliability: (i) the Si–SiO2 interface, and (ii) the internal interface between SiO2 and the high-k dielectric. Spectroscopic studies combined with ab initio electronic structure calculations and bond constraint theory (BCT) identify quantitative relationships between electronic and/or mechanical strain and densities of defects and defect precursors at these interfaces. Discontinuities in the number of bonds/atom, Nav at these dielectric interfaces introduce high densities of defects that scale as the square of Nav. BCT also explains the driving force for nano-scale self-organizations at these interfaces, and the effect this has on defect densities, and other interfacial properties. DA - 2005/8/22/ PY - 2005/8/22/ DO - 10.1016/j.tsf.2004.11.224 VL - 486 IS - 1-2 SP - 200-204 SN - 0040-6090 KW - interfacial defects and defect precursors KW - interfacial transition regions KW - internal dielectric interfaces KW - self-organization KW - bond constraint theory ER - TY - JOUR TI - Conduction band-edge d-states in high-k dielectrics due to Jahn-Teller term splittings AU - Lucovsky, G AU - Fulton, CC AU - Zhang, Y AU - Luning, J AU - Edge, L AU - Whitten, JL AU - Nemanich, RJ AU - Schlom, DG AU - Afanase'v, , VV T2 - THIN SOLID FILMS AB - X-ray absorption spectroscopy (XAS) is used to study conduction band edge electronic structure of high-k transition metal (TM) and trivalent lanthanide series rare earth (RE) oxide dielectrics. Empty TM/RE d-states are studied by intra-atomic transitions originating in core level spin-orbit split p-states, and conduction band states are studied in inter-atomic transitions which originate in the oxygen atom 1s core level state. In non-crystalline Zr and Hf silicate alloys, the local bonding symmetry, or crystal field splits these d-states into doubly and triply degenerate features. In nano-crystalline oxides, there are additional d-state splittings due to contributions of more distant neighbors that completely remove d-state degeneracies via the Jahn–Teller effect mechanism. This gives rise to highly localized band edge states that are electronically active in photoconductivity, internal photoemission, and act as bulk traps in metal oxide semiconductor (MOS) devices. DA - 2005/8/22/ PY - 2005/8/22/ DO - 10.1016/j.tsf.2004.11.233 VL - 486 IS - 1-2 SP - 129-135 SN - 0040-6090 KW - transition metal/rare earth oxides KW - complex oxides KW - band edge d-states KW - Jahn-Teller term splittings KW - localized band edge states KW - bulk trapping ER - TY - JOUR TI - Characterization of dried whey protein concentrate and isolate flavor AU - Whetstine, MEC AU - Croissant, AE AU - Drake, MA T2 - JOURNAL OF DAIRY SCIENCE AB - The flavor of whey protein concentrates (WPC 80) and whey protein isolates (WPI) was studied using instrumental and sensory techniques. Four WPC 80 and 4 WPI, less than 3 mo old, were collected in duplicate from 6 manufacturers in the United States. Samples were rehydrated and evaluated in duplicate by descriptive sensory analysis. Duplicate samples with internal standards were extracted with diethyl ether. Extracts were then distilled to remove nonvolatile material using high vacuum distillation. Volatile extracts were analyzed using gas chromatography/olfactometry with post peak intensity analysis and aroma extract dilution analysis. Compounds were identified by comparison of retention indices, odor properties, and gas chromatography/mass spectrometry against reference standards. Whey proteins exhibited sweet aromatic, cardboard/wet paper, animal/wet dog, soapy, brothy, cucumber, and cooked/milky flavors, along with the basic taste bitter, and the feeling factor astringency. Key volatile flavor compounds in WPC 80 and WPI were butanoic acid (cheesy), 2-acetyl-1-pyrroline (popcorn), 2-methyl-3-furanthiol (brothy/burnt), 2,5-dimethyl-4-hydroxy-3-(2H)-furanone (maple/spicy), 2-nonenal (fatty/old books), (E,Z)-2,6-nonadienal (cucumber), and (E,Z)-2,4-decadienal (fatty/oxidized). This baseline data on flavor and flavor sources in whey proteins will aid ongoing and future research and will help to identify the most appropriate whey ingredients to use to control or minimize flavor variability in whey enhanced products. DA - 2005/11// PY - 2005/11// DO - 10.3168/jds.S0022-0302(05)73068-X VL - 88 IS - 11 SP - 3826-3839 SN - 1525-3198 KW - whey protein concentrate KW - whey protein isolate KW - flavor ER - TY - JOUR TI - Analysis of variable scale surface roughness on Si(111): a comparative Brewster angle, ellipsometry and atomic force microscopy investigation AU - Lublow, M AU - Lewerenz, HJ T2 - TRANSACTIONS OF THE INSTITUTE OF METAL FINISHING AB - AbstractBrewster angle analysis (BAA) and single wavelength ellipsometry (SWE) were used to investigate the optical response of Si(111), exposed to subsequent 40% NH4F etching steps, each persisting for 20 s. During native oxide layer etchback and anisotropic etching of the silicon substrate, ultrasmall variations were accurately observed. Contact mode atomic force microscopy (CM AFM) was performed to describe the scale dependence of roughness analysis and to correlate optical and micro-topographical information. It can be shown that BAA and SWE are of comparable sensitivity with respect to variations in film thickness and surface roughness. Quantitative analysis, however, leads to new insights into the information obtainable from the optical methods. BAA data, i.e. the Brewster angle and the reflectance at the Brewster angle, change each in a unique direction, if a clean and smooth surface slightly deteriorates. Ellipsometry, however, shows more complicated variations of the data depending on the concurrent presence of small and long correlation length surface roughness. A combination of both methods allows separating and quantification of these roughness contributions.Keywords: SILICON ETCHINGTHIN FILMSROUGHNESSELLIPSOMETRYREFLECTOMETRYAFM DA - 2005/9// PY - 2005/9// DO - 10.1179/002029605X70450 VL - 83 IS - 5 SP - 238-247 SN - 1745-9192 KW - silicon etching KW - thin films KW - roughness KW - ellipsometry KW - reflectometry KW - AFM ER - TY - JOUR TI - An electronically tunable microstrip bandpass filter using thin-film barium-strontium-titanate (BST) varactors AU - Nath, J AU - Ghosh, D AU - Maria, JP AU - Kingon, AI AU - Fathelbab, W AU - Franzon, PD AU - Steer, MB T2 - IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES AB - A tunable third-order combline bandpass filter using thin-film barium-strontium-titanate varactors and fabricated on a sapphire substrate is reported. Application of 0-200-V bias varied the center frequency of the filter from 2.44 to 2.88 GHz (16% tuning) while achieving a 1-dB bandwidth of 400 MHz. The insertion loss varied from 5.1 dB at zero bias to 3.3 dB at full bias, while the return loss exceeded 13 dB over the range. The third-order intercept of the filter was found to be 41 dBm. DA - 2005/9// PY - 2005/9// DO - 10.1109/TMTT.2005.854196 VL - 53 IS - 9 SP - 2707-2712 SN - 1557-9670 KW - barium strontium titanate (BST) KW - combline filter KW - ferroelectric films KW - intermodulation distortion KW - microstrip filters KW - resonators KW - thin-film devices KW - tunable filters KW - varactor ER - TY - JOUR TI - A new understanding of near-threshold damage for 200 keV irradiation in silicon AU - Stoddard, N AU - Duscher, G AU - Windl, W AU - Rozgonyi, G T2 - JOURNAL OF MATERIALS SCIENCE DA - 2005/7// PY - 2005/7// DO - 10.1007/s10853-005-1059-z VL - 40 IS - 14 SP - 3639-3650 SN - 1573-4803 ER - TY - JOUR TI - Studies of the coupling of final d*-states in mixed Hf and Ti oxides (HfO2)(x)(TiOx)(1-x) and other complex oxides AU - Fulton, CC AU - Lucovsky, G AU - Zhang, Y AU - Zou, Y AU - Nemanich, RJ AU - Ade, H AU - Whitten, JL T2 - JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA AB - Abstract X-ray absorption spectroscopy and vacuum ultra-violet spectroscopic ellipsometry are used to study the electronic structure of complex oxides comprised of mixed TM/TM and TM/RE oxides. Experimental spectra for HfTiO 4 and Gd(Dy)ScO 3 indicate multiple d-state features in the O K 1 edge. These are compared with the empirical models for atomic d-state mixing. It is concluded that a mean field, virtual alloy model does not apply, and that the effects associated with the differences in atomic coordination and deviations from ideal octahedral or cubic bonding play a determinant role in d-state atom mixing. The results are applied band edge engineering options for high- k dielectric applications. DA - 2005/6// PY - 2005/6// DO - 10.1016/j.elspec.2005.01.098 VL - 144 SP - 913-916 SN - 1873-2526 KW - complex oxides KW - x-ray absorption spectra KW - spectroscopic ellipsometry KW - d-State coupling KW - band gap engineering ER - TY - JOUR TI - Structural defects and luminescence features in heteroepitaxial GaN grown on on-axis and misoriented substrates AU - Bai, J. AU - Dudley, M. AU - Chen, L. AU - Skromme, B. J. AU - Wagner, B. AU - Davis, R. F. AU - Chowdhury, U. AU - Dupuis, R. D. T2 - Journal of Applied Physics DA - 2005/// PY - 2005/// VL - 97 IS - 11 ER - TY - JOUR TI - Structural TEM study of nonpolar a-plane gallium nitride grown on (1120) 4H-SiC by organometallic vapor phase epitaxy AU - Zakharov, D. N. AU - Liliental-Weber, Z. AU - Wagner, B. AU - Reitmeier, Z. J. AU - Preble, E. A. AU - Davis, R. F. T2 - Physical Review. B, Condensed Matter and Materials Physics DA - 2005/// PY - 2005/// VL - 71 IS - 23 ER - TY - JOUR TI - Silicon-on-diamond: An advanced silicon-on-insulator technology AU - Aleksov, A AU - Li, X AU - Govindaraju, N AU - Gobien, JM AU - Wolter, SD AU - Prater, JT AU - Sitar, Z T2 - DIAMOND AND RELATED MATERIALS AB - Silicon-on-diamond (SOD) technology is proposed as an advanced alternative to conventional silicon-on-insulator (SOI) technology. In SOD, the electrical insulator is diamond, the best thermal conductor in nature. In our SOD concept, the diamond film is highly oriented (HOD), 75–100 μm thick and serves as an electrical insulator, heat spreader and substrate. In this paper, we focus on the thermal evaluation of SOD with a Si device layer on the nucleation side of the diamond film. The obtained results indicated that SOD can sustain up to 10-times higher power loads than SOI. The results were experimentally obtained by R(T) measurements of micro-heaters deposited on the Si device layer and by thermal imaging. 3D finite element thermal simulations using ANSYS confirmed that these numbers are in good agreement with expectations. DA - 2005/// PY - 2005/// DO - 10.1016/j.diamond.2005.01.019 VL - 14 IS - 3-7 SP - 308-313 SN - 1879-0062 KW - silicon-on-diamond (SOD) KW - heaters KW - IR-imaging KW - 3D-FE ER - TY - JOUR TI - Self-assembling of nanocavities in TiO2 dispersed with Au nanoclusters AU - Wang, C. M. AU - Zhang, Y. AU - Shutthanandan, V. AU - Baer, D. R. AU - Weber, W. J. AU - Thomas, L. E. AU - Thevuthasan, S. AU - Duscher, G. T2 - Physical Review. B, Condensed Matter and Materials Physics DA - 2005/// PY - 2005/// VL - 72 IS - 24 ER - TY - JOUR TI - Relative bulk and interface contributions to optical second-harmonic generation in silicon AU - Peng, HJ AU - Adles, EJ AU - Wang, JFT AU - Aspnes, DE T2 - PHYSICAL REVIEW B AB - Using the simplified bond-hyperpolarizability model, we obtain analytic expressions for the first-forbidden (spatial dispersion, magnetic dipole/electric quadrupole) bulk contributions to second-harmonic generation for centrosymmetric materials. Applying these to oxidized Si, we show theoretically and by comparison to experiment that the relative bulk contribution near $800\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ is minor, less than half that of the interface, but that the coherent superposition of bulk and interface contributions is important and cannot be neglected. DA - 2005/11// PY - 2005/11// DO - 10.1103/physrevb.72.205203 VL - 72 IS - 20 SP - SN - 1098-0121 ER - TY - JOUR TI - Optical properties of (GaSb)(3n)(AlSb)(n) (1 <= n <= 5) superlattices AU - Choi, SG AU - Srivastava, SK AU - Palmstrom, CJ AU - Kim, YD AU - Cooper, SL AU - Aspnes, DE T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B AB - We report room-temperature pseudodielectric function spectra ⟨ε(ω)⟩=⟨ε1(ω)⟩+i⟨ε2(ω)⟩ from 1.5 to 6.0 eV of a series of (GaSb)3n(AlSb)n(1⩽n⩽5) short-period superlattices (SLs) and the corresponding ternary alloy, Al0.3Ga0.7Sb, as determined by spectroscopic ellipsometry. An in situ chemical etching procedure was performed to minimize the effect of surface oxides and other overlayers. For small periods (n⩽2), the dielectric responses of the SLs are similar to those of the random alloy. For larger n, structures due to the E1, E1+Δ1, E0′, E2, and E1′ interband transitions can be seen, with the E1, E1+Δ1, and E0′ structures showing a clear SL-period dependence. Two additional features were also observed near the E1+Δ1 structure for n⩾4. DA - 2005/// PY - 2005/// DO - 10.1116/1.1881552 VL - 23 IS - 3 SP - 1149-1153 SN - 2166-2746 ER - TY - JOUR TI - On the strain rate sensitivity of the flow stress of ultrafine-grained Cu processed by equal channel angular extrusion (ECAE) AU - Conrad, H AU - Jung, K T2 - SCRIPTA MATERIALIA AB - The strain rate sensitivity of the flow stress of ultrafine-grained Cu processed by ECAE is compared with that of vapor-deposited and electrodeposited Cu. The results for all three processing methods were in accord with the model of grain boundary shear promoted by the pile-up of dislocations. DA - 2005/9// PY - 2005/9// DO - 10.1016/j.scriptamat.2005.04.030 VL - 53 IS - 5 SP - 581-584 SN - 1359-6462 KW - Cu KW - ultrafine grain size KW - flow stress KW - strain-rate sensitivity KW - grain boundary shear ER - TY - JOUR TI - Growth and field emission properties of small diameter carbon nanotube films AU - Wang, YY AU - Gupta, S AU - Garguilo, JM AU - Liu, ZJ AU - Qin, LC AU - Nemanich, RJ T2 - DIAMOND AND RELATED MATERIALS AB - Vertically aligned carbon nanotube films with diameters smaller than 5 nm, high densities up to 1012/cm2, and lengths of ∼ 5–8 μm were deposited by microwave plasma-assisted chemical vapor deposition. Experiments show that, by continuous reduction in the thickness of the iron film (i.e., ∼0.3–0.5 nm), small diameter carbon nanotubes can be achieved with diameters that ranged from 1–5 nm, and the films are comprised of both single- and double-wall nanotubes. The electron field emission properties of the films were investigated by variable distance field emission and temperature-dependent field electron emission microscopy (T-FEEM). The films showed an emission site density of ∼104/cm2 and a threshold field of 2.8 V/μm similar to multiwalled nanotubes (1.9 V/μm). In addition, they also exhibited a temperature dependence of the emission site intensity. DA - 2005/// PY - 2005/// DO - 10.1016/j.diamond.2004.10.003 VL - 14 IS - 3-7 SP - 714-718 SN - 1879-0062 KW - small diameter carbon nanotubes KW - MWCVD KW - growth KW - field emission ER - TY - JOUR TI - Formation of stable titanium germanosilicide thin films on Si1-xGex AU - Burnette, JE AU - Nemanich, RJ AU - Sayers, DE T2 - JOURNAL OF APPLIED PHYSICS AB - The sequential deposition of strained Si1−xGex with concentrations x=0.20 and 0.30, amorphous silicon, and titanium on Si (100) after annealing at 700°C leads to the formation of a C54 Ti(Si1−yGey)2∕Si1−xGex bilayer, the phase formation and interface stability of which are studied. The use of an amorphous layer of Si is employed to eliminate or decrease the formation of germanium-rich Si1−zGez alloy precipitates found in the solid-phase reaction of Ti and Si1−xGex. It has been proposed that the precipitation phenomenon was driven by differences in the enthalpy of formation as a function of concentration in the Ti(Si1−yGey)2 layer, resulting from the enthalpy difference between TiSi2 and TiGe2 compounds, both of which are assumed to be completely miscible with one another. Layers of amorphous silicon of varying thicknesses were incorporated between a 300-Å Ti layer and the strained Si1−xGex substrate layer to achieve Ti(Si1−yGey)2 films that are in equilibrium with the Si1−xGex substrate. The use of amorphous silicon layers of varying thicknesses indicated that Ti(Si1−yGey)2∕Si1−xGex films could be formed with the absence of germanium-rich precipitates at the grain boundaries, depending on the amorphous silicon layer thickness. DA - 2005/6/1/ PY - 2005/6/1/ DO - 10.1063/1.1923164 VL - 97 IS - 11 SP - SN - 1089-7550 ER - TY - JOUR TI - Final state effects in VUV and soft X-ray absorption spectra of transition metal oxides and silicate alloys: comparisons between experiment and ab initio calculations AU - Lucovsky, G AU - Zhang, Y AU - Fulton, CC AU - Zou, Y AU - Nemanich, RJ AU - Ade, H AU - Whitten, JL T2 - JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA AB - This paper uses X-ray absorption spectroscopy and vacuum ultra-violet spectroscopic ellipsometry to study the electronic structure of high-k transition metal (TM) oxide gate dielectrics. The results are applicable to TM and rare earth (RE) silicate and aluminate alloys, as well as complex oxides comprised of mixed TM/TM and TM/RE oxides. These studies identify the nature of the lowest conduction band d* states, which define the optical band gap, including their relationship to the band gap, Eg, of the oxide. DA - 2005/6// PY - 2005/6// DO - 10.1016/j.elspec.2005.01.251 VL - 144 SP - 917-919 SN - 1873-2526 KW - transition metal oxides KW - x-ray absorption spectra KW - intra- and inter-atomic transitions KW - spectroscopic ellipsometry ER - TY - JOUR TI - Field enhanced thermionic electron emission from sulfur doped nanocrystalline diamond films AU - Kock, FAM AU - Garguilo, JM AU - Nemanich, RJ T2 - DIAMOND AND RELATED MATERIALS AB - Thermal activation of field enhancement based emitters can provide efficient means of lowering the emission barrier, thus enabling high current density electron sources. Microwave plasma assisted chemical vapour deposition was employed to synthesize sulfur doped nanocrystalline diamond films with various sulfur/carbon concentrations. Electron emission at elevated temperatures was characterized by direct imaging of the emission utilizing electron emission microscopy. Sulfur doped nanocrystalline diamond films exhibit electron emission from singular sites indicating a non-uniform distribution of the local field enhancement. The threshold field for electron emission changes significantly by varying the sulfur/carbon concentration in the gas phase. At elevated temperatures the emission is strongly enhanced but remains confined to the intense emission sites. DA - 2005/// PY - 2005/// DO - 10.1016/j.diamond.2004.12.056 VL - 14 IS - 3-7 SP - 704-708 SN - 1879-0062 KW - nanocrystalline KW - doping KW - thermionic emission KW - energy conversion ER - TY - JOUR TI - Enhanced phenomena in metals with electric and magnetic fields: I Electric fields AU - Conrad, H T2 - MATERIALS TRANSACTIONS AB - The effects of an externally-applied electric field on the equilibria and kinetics of solid state transformations in metals and alloys are reviewed. Regarding equilibria, electric fields have been found to affect the solubility of solutes and the composition as well as volume fraction of phases present. Regarding kinetics, electric fields have been shown to affect recovery and recrystallization, precipitation, phase coarsening, hardenability and sintering. Electric fields thus offer an additional means of controlling microstructure and in turn properties. Our understanding of the effects of an electric field on solid state transformations in metals and alloys is very meager. It appears that most of the observed effects on kinetics are through its influence on vacancies. DA - 2005/6// PY - 2005/6// DO - 10.2320/matertrans.46.1083 VL - 46 IS - 6 SP - 1083-1087 SN - 1347-5320 KW - electric field KW - solubility KW - recovery KW - recrystallization KW - precipitation KW - phase coarsening KW - hardenability KW - sintering ER - TY - JOUR TI - Effects of processing conditions on the dielectric properties of CaCu3Ti4O12 AU - Aygun, S AU - Tan, XL AU - Maria, JP AU - Cann, D T2 - JOURNAL OF ELECTROCERAMICS DA - 2005/12// PY - 2005/12// DO - 10.1007/s10832-005-3191-1 VL - 15 IS - 3 SP - 203-208 SN - 1573-8663 KW - dielectric materials KW - space charge KW - perovskite KW - Maxwell-Wagner ER - TY - JOUR TI - Effect of temperature on transitions in creep mechanisms in class-A alloys AU - Murty, KL AU - Dentel, G AU - Britt, J T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING AB - Alloy class materials exhibit viscous glide controlled creep, where dislocations are locked by solute atoms thereby decreasing their glide velocity while dislocation annihilation by climb still occurs. The creep-rate here varies as cube of the applied stress (stress exponent, n = 3) while the activation energy for creep becomes equal to that for solute atom diffusion. At high enough stress, the dislocations get freed from solute atom locking and transition to climb controlled creep is noted with n ∼ 5 while at still higher stresses, power-law breakdown is observed. For relatively small grain-sizes, viscous creep mechanisms such as Nabarro–Herring or Coble creep usually occur at low stresses. A close examination of the model equations reveals that at temperatures below a critical temperature, a transition from diffusional viscous creep to dislocation climb occurs without the intermediate viscous glide creep. Recent experimental results on a Zr–Nb sheet clearly follow these formulations exhibiting narrower intermediate region with decreasing temperature. DA - 2005/11/25/ PY - 2005/11/25/ DO - 10.1016/j.msea.2005.08.006 VL - 410 SP - 28-31 SN - 0921-5093 KW - creep KW - transitions KW - climb KW - glide KW - zirconium KW - diffusion ER - TY - JOUR TI - Dislocation density model for the effect of grain size on the flow stress of a Ti-15.2 at.% Mo beta-alloy at 4.2-650 K AU - Chia, KH AU - Jung, K AU - Conrad, H T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING AB - Hall–Petch (H–P) plots of the effect of grain size d = 4.6–22 μm on the flow stress σ at 4.2–650 K of a β-Ti–15.2 at.% Mo alloy gave that the parameter σi increased with strain ɛ and with decrease in temperature T. In contrast, the parameter KH–P was relatively independent of ɛ and T. The corresponding dislocation density ρ increased with ɛ and with decrease in d, giving the well-known relation σ/M ≈0.5 μbρ1/2, where M is the Taylor factor. The magnitudes of σi and KH–P calculated from ρ were in reasonable agreement with those obtained from the H–P plots. The grain size dependence of σ was in accord with Li's grain boundary ledge mechanism. DA - 2005/11/15/ PY - 2005/11/15/ DO - 10.1016/j.msea.2005.03.117 VL - 409 IS - 1-2 SP - 32-38 SN - 1873-4936 KW - Ti-Mo KW - grain size KW - Hall-Petch KW - dislocation density KW - grain boundary ledges ER - TY - JOUR TI - Direct studies of domain switching dynamics in thin film ferroelectric capacitors AU - Gruverman, A AU - Rodriguez, BJ AU - Dehoff, C AU - Waldrep, JD AU - Kingon, AI AU - Nemanich, RJ AU - Cross, JS T2 - APPLIED PHYSICS LETTERS AB - An experimental approach for direct studies of the polarization reversal mechanism in thin film ferroelectric capacitors based on piezoresponse force microscopy (PFM) in conjunction with pulse switching capabilities is presented. Instant domain configurations developing in a 3×3μm2 capacitor at different stages of the polarization reversal process have been registered using step-by-step switching and subsequent PFM imaging. The developed approach allows direct comparison of experimentally measured microscopic switching behavior with parameters used by phenomenological switching models. It has been found that in the low field regime (just above the threshold value) used in the present study, the mechanism of polarization reversal changes during the switching cycle from the initial nucleation-dominated process to the lateral domain expansion at the later stages. The classical nucleation model of Kolmogorov–Avrami–Ishibashi (KAI) provides reasonable approximation for the nucleation-dominated stage of switching but is inapplicable to the slow switching stage. It has been suggested that the switching dynamics can be approximated by averaging the KAI model over a broad distribution of switching times. DA - 2005/8/22/ PY - 2005/8/22/ DO - 10.1063/1.2010605 VL - 87 IS - 8 SP - SN - 1077-3118 ER - TY - JOUR TI - Dielectric and microstructural properties of barium titanate zirconate thin films on copper substrates AU - Ihlefeld, JF AU - Maria, JP AU - Borland, W T2 - JOURNAL OF MATERIALS RESEARCH DA - 2005/10// PY - 2005/10// DO - 10.1557/JMR.2005.0342 VL - 20 IS - 10 SP - 2838-2844 SN - 2044-5326 ER - TY - JOUR TI - Crucible materials for growth of aluminum nitride crystals AU - Schlesser, R AU - Dalmau, R AU - Zhuang, D AU - Collazo, R AU - Sitar, Z T2 - JOURNAL OF CRYSTAL GROWTH AB - The growth of aluminum nitride (AlN) bulk crystals by sublimation of an AlN source requires elevated temperatures, typically in a range of 1800–2300 °C. These temperature requirements, combined with the chemically aggressive nature of the Al vapor, severely limit the choice of reactor hot-zone materials, and most notably, the selection of reaction crucibles. Aside from refractory elements, potentially promising compound materials include refractory nitrides, carbides, and borides. In this work, TaC crucibles were fabricated using a binderless sintering process and were tested in AlN bulk growth experiments. Elemental analysis of crystals grown in these crucibles revealed extremely low Ta contamination, below the analytical detection limit of 1 ppm by weight and C contamination levels as low as 50 ppm by weight; C contamination likely originated from sources unrelated to the crucible material. Crucibles were re-used in several consecutive growth runs; average crucible lifetimes exceeded 200 h at growth temperatures exceeding 2200 °C. DA - 2005/7/15/ PY - 2005/7/15/ DO - 10.1016/j.jcrysgro.2005.03.014 VL - 281 IS - 1 SP - 75-80 SN - 0022-0248 KW - impurities KW - growth from vapor KW - nitrides ER - TY - JOUR TI - Consolidation of a Cu-2.5 vol.% Al2O3 powder using high energy mechanical milling AU - Zhang, DL AU - Raynova, S AU - Koch, CC AU - Scattergood, RO AU - Youssef, KM T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING AB - Abstract In situ consolidation of a Cu–2.5 vol.% Al 2 O 3 powder by high energy ball milling has been studied by examining changes of size, morphology, macrostructure and microstructure of the powder particles, lumps, and balls formed with increasing milling time under different conditions. This study clearly demonstrates that the consolidation of the Cu–2.5 vol.% Al 2 O 3 powder by high energy ball milling is accomplished initially by coalescence of powder particles through cold welding which leads to formation of lumps, then by cold welding and re-shaping of the lumps into small balls, and finally by cold welding of small balls into larger balls. The maximum diameter of the large balls is comparable with the diameter of the milling balls used as a milling medium. The two types of defects in the consolidated lumps and balls in the large balls, concentrated voids and crack-like voids, show that the material undergoes a large amount of plastic flow during the process of consolidation. The consolidation of the Cu–2.5 vol.% Al 2 O 3 powder can also been achieved by a combination of cryomilling and room temperature milling, but the consolidation process is slower due to increased hardness of the powder particles. The study also shows that the Al 2 O 3 fine particles are incorporated into the Cu matrix forming a composite structure when the lumps are formed, and the large balls exhibit a nanostructure with grain sizes smaller than 100 nm. DA - 2005/11/25/ PY - 2005/11/25/ DO - 10.1016/j.msea.2005.08.109 VL - 410 SP - 375-380 SN - 0921-5093 KW - high energy mechanical milling KW - powder consolidation KW - nanostructure KW - copper KW - nanocomposite ER - TY - JOUR TI - Atomic resolution imaging of Au nanocluster dispersed in TiO2, SrTiO3, and MgO AU - Wang, CM AU - Shutthanandan, V AU - Zhang, Y AU - Thevuthasan, S AU - Duscher, G T2 - JOURNAL OF THE AMERICAN CERAMIC SOCIETY AB - Gold nanoclusters dispersed in single crystal TiO 2 , MgO, and SrTiO 3 have been prepared by ion implantation at 300–975 K and subsequent annealing at 1275 K for 10 h. High‐resolution transmission electron microscopy and high‐angle annular dark field (HAADF) imaging in aberration corrected scanning transmission electron microscope (STEM) have been used to characterize the microstructure of the gold nanoclusters dispersed materials. STEM‐HAADF imaging with atomic resolution has directly revealed for all three materials that Au atoms partially occupy cation lattice positions. Cavities up to several tens of nanometers were observed in MgO and SrTiO 3 . The cavities and gold clusters are spatially associated in MgO and SrTiO 3 , indicating a strong interaction between the Au cluster and cavities. For MgO and SrTiO 3 , the faceting planes appear to be the same for both nanometer‐sized cavity and the Au cluster, demonstrating that both the surface energy and the interfacial energy between Au cluster and the matrix are lowest on these planes. DA - 2005/11// PY - 2005/11// DO - 10.1111/j.1551-2916.2005.00579.x VL - 88 IS - 11 SP - 3184-3191 SN - 0002-7820 ER - TY - JOUR TI - AlN bulk crystals grown on SiC seeds AU - Dalmau, R AU - Schlesser, R AU - Rodriguez, BJ AU - Nemanich, RJ AU - Sitar, Z T2 - JOURNAL OF CRYSTAL GROWTH AB - AlN layers with thickness between 0.1 and 3 mm were grown on on-axis and off-axis (0 0 0 1), Si-face SiC seeds by physical vapor transport (PVT) from an AlN powder source. A two-step deposition process was developed for the growth of thick layers. Cracks formed in the AlN layers due to the thermal expansion mismatch between AlN and SiC were observed to decrease with increase in AlN thickness. AlN grown on on-axis SiC was primarily Al-polar, but contained N-polar inversion domains (IDs) revealed by wet etching in hot, aqueous phosphoric acid or potassium hydroxide solutions. Regions of opposite polarity on basal plane surfaces were imaged by piezoresponse force microscopy (PFM). IDs were not observed in crystals grown on off-axis seeds. The influence of SiC seed orientation and stability on the polarity of the AlN layers is discussed. DA - 2005/7/15/ PY - 2005/7/15/ DO - 10.1016/j.jcrysgro.2005.03.012 VL - 281 IS - 1 SP - 68-74 SN - 1873-5002 KW - growth from vapor KW - seed crystals KW - nitrides ER - TY - JOUR TI - Synchrotron x-ray studies of vitreous SiO2 over Si(001). II. Crystalline contribution AU - Castro-Colin, M AU - Donner, W AU - Moss, SC AU - Islam, Z AU - Sinha, SK AU - Nemanich, R T2 - PHYSICAL REVIEW B AB - Thermally oxidized thin films grown on Si(001) were analyzed with synchrotron x rays. By looking at crystal truncation rod (CTR) profiles we were able to observe, as have others, a crystalline peak, nominally along the (1 1 $L$) rod, together with Laue oscillations matching the film thickness. These oscillations are evidence of a crystalline component present throughout the entire film that vanishes away from the interface with the silicon substrate. A model consisting of distorted coesite is proposed to explain the results. DA - 2005/1// PY - 2005/1// DO - 10.1103/physrevb.71.045311 VL - 71 IS - 4 SP - SN - 1098-0121 ER - TY - JOUR TI - Synchrotron x-ray studies of vitreous SiO2 over Si(001). I. Anisotropic glass contribution AU - Castro-Colin, M AU - Donner, W AU - Moss, SC AU - Islam, Z AU - Sinha, SK AU - Nemanich, R AU - Metzger, HT AU - Bosecke, P AU - Shulli, T T2 - PHYSICAL REVIEW B AB - While numerous investigations of the structure and interface of amorphous ${\mathrm{SiO}}_{2}$ thermally grown on Si, theoretical as well as experimental, have been carried out over the years, a definitive picture of this thin gate oxide and its interface remains lacking. We have explored this issue using synchrotron x rays in grazing incidence geometry. In this geometry a fourfold modulation in the first sharp diffraction peak (FSDP) from thin vitreous ${\mathrm{SiO}}_{2}$ of 100 and 500 \AA{} thickness can be observed. While the FSDP exhibits a modulation throughout the entire film, this modulation decays away from the interface. Reflectivity measurements were also performed, which reveal an interfacial layer of 3% density increase in the ${\mathrm{SiO}}_{2}$ film over the bulk (film) density. DA - 2005/1// PY - 2005/1// DO - 10.1103/physrevb.71.045310 VL - 71 IS - 4 SP - SN - 1098-0121 ER - TY - JOUR TI - Short-beam three-point bend tests in syntactic foams. Part II: Effect of microballoons content on shear strength AU - Kishore, Shankar R. AU - Sankaran, S. T2 - Journal of Applied Polymer Science DA - 2005/// PY - 2005/// VL - 98 IS - 2 SP - 680-686 ER - TY - JOUR TI - Short-beam three-point bend test study in syntactic foam. Part III: Effects of interface modification on strength and fractographic features AU - Kishore, Shankar R. AU - Sankaran, S. T2 - Journal of Applied Polymer Science DA - 2005/// PY - 2005/// VL - 98 IS - 2 SP - 687-693 ER - TY - JOUR TI - Short beam three point bend tests in syntactic foams. Part 1: Microscopic characterization of the failure zones AU - Kishore, Shankar R. AU - Sankaran, S. T2 - Journal of Applied Polymer Science DA - 2005/// PY - 2005/// VL - 98 IS - 2 SP - 673-679 ER - TY - JOUR TI - Segregation and enhanced diffusion of nitrogen in silicon induced by low energy ion bombardment AU - Stoddard, N AU - Duscher, G AU - Karoui, A AU - Stevie, F AU - Rozgonyi, G T2 - JOURNAL OF APPLIED PHYSICS AB - A sample of nitrogen-doped, single crystal Czochralski silicon was subjected to several different surface preparations. Secondary ion mass spectrometry depth profiling has shown that prolonged glancing-angle bombardment by 3–5kV Ar+ ions significantly increases the nitrogen concentration in the near surface by up to an order of magnitude over the bulk value. Concentrations are observed to be elevated over the bulk value to a depth up to 25μm. Nitrogen-implanted samples and samples with a 1nm surface nitride did not exhibit nitrogen segregation under the same conditions, but a sample with 100nm of surface nitride did exhibit ion bombardment induced drive-in. In nitride-free samples, the source of the nitrogen is indicated to be a nitrogen-rich layer in the first micron of material. The diffusion behavior of nitrogen in silicon is discussed and the Crowdion mechanism for diffusion is suggested as the enabling mechanism for the enhanced low temperature diffusion. DA - 2005/4/15/ PY - 2005/4/15/ DO - 10.1063/1.1866480 VL - 97 IS - 8 SP - SN - 1089-7550 ER - TY - JOUR TI - Secondary electron emission of chemical-vapor-deposited diamond by impact of slow H+, D+, H-2(+), C+, O+, and O-2(+) ions AU - Wieser, M AU - Wurz, P AU - Nemanich, RJ AU - Fuselier, SA T2 - JOURNAL OF APPLIED PHYSICS AB - We report on the measurements of the secondary electron yield of chemical-vapor-deposited diamond upon the reflection of primary H+, D+, H2+, C+, O+, and O2+ ions in an energy range of 50–1000 eV per atom at a 60° angle of incidence to the surface normal. Depending on the species and energy, a secondary electron yield between 0.1 and 2 was observed and remained unchanged over weeks without further periodic reconditioning of the surface and in spite of the moderate vacuum environment of 10−7mbar. Semiempirical fit functions were found with a dependence on the inverse velocity and the square root of the atomic number of the projectiles. DA - 2005/8/1/ PY - 2005/8/1/ DO - 10.1063/1.1996855 VL - 98 IS - 3 SP - SN - 0021-8979 ER - TY - JOUR TI - Scanning electron microscopy cathodoluminescence studies of piezoelectric fields in an InGaN/GaN quantum-well light-emitting diode AU - Bunker, KL AU - Garcia, R AU - Russell, PE T2 - APPLIED PHYSICS LETTERS AB - Scanning electron microscopy (SEM) cathodoluminescence (CL) experiments were used to determine the existence and direction of piezoelectric fields in a commercial InGaN multiple-quantum-well (MQW) light-emitting diode (LED). The CL emission peak showed a blueshift with increasing reverse bias due to the cancellation of the piezoelectric field. A full compensation of the piezoelectric field was observed followed by a redshift with a further increase of reverse bias, indicating that flat-band conditions had been reached. We determined the piezoelectric field points in the [000-1] direction and estimated the magnitude to be approximately 1MV∕cm. SEM-CL carrier generation density variation and electroluminescence experiments were also used to confirm the existence of a piezoelectric field in the InGaN MQW LED. DA - 2005/2/21/ PY - 2005/2/21/ DO - 10.1063/1.1868886 VL - 86 IS - 8 SP - SN - 1077-3118 ER - TY - JOUR TI - Oxidation potentials of human eumelanosomes and plheomelanosomes AU - Samokhvalov, A AU - Hong, L AU - Liu, Y AU - Garguilo, J AU - Nemanich, RJ AU - Edwards, GS AU - Simon, JD T2 - PHOTOCHEMISTRY AND PHOTOBIOLOGY AB - Eumelanosomes and pheomelanosomes isolated from black and red human hair, respectively, were studied by photoelectron emission microscopy (PEEM). PEEM images were collected at various wavelengths between 207 and 344 nm, using the spontaneous emission output of the Duke OK-4 free electron laser (FEL). Analysis of the FEL-PEEM data revealed ionization thresholds of 4.6 and 3.9 eV corresponding to oxidation potentials of -0.2 and +0.5 V vs normal hydrogen electrode for eumelanosomes and pheomelanosomes, respectively. The difference in oxidation potential is attributed to the pigment content of the melanosome, namely whether it contains primarily eumelanin and pheomelanin. The effect of added melanosomes on the reduction of Fe(III)-cytochrome showed pheomelanosomes are stronger reducing agents than eumelanosomes, consistent with the measured oxidation potentials. The FEL-PEEM experiment offers to be an important new approach for quantifying the effects of age, oxidation and metal accumulation on the oxidation potentials of intact melanosomes. DA - 2005/// PY - 2005/// DO - 10.1562/2004-07-23-RC-245.1 VL - 81 IS - 1 SP - 145-148 SN - 1751-1097 ER - TY - JOUR TI - On the surface chemistry of silicon under reducing conditions: An SRPES investigation AU - Skorupska, K AU - Lublow, M AU - Kanis, M AU - Jungblut, H AU - Lewerenz, HJ T2 - ELECTROCHEMISTRY COMMUNICATIONS AB - Abstract Silicon electrodes were conditioned in alkaline solution at potentials negative from open circuit (ocp). The dark I–V characteristic of n-Si(1 1 1) in accumulation reveals Butler–Volmer behaviour for outer sphere charge transfer of the hydrogen evolution reaction. Deconvoluted synchrotron radiation photoelectron spectroscopy (SRPES) data are used to identify reaction intermediates of the chemical and electrochemical pathways and are compared to existing models on a molecular base. The results indicate the existence of postulated negatively charged surface species. Comparison of density functional theory (DFT) calculations and core level binding energy shifts of the Si 2p 3/2 , the 2p 1/2 line and the O 1s line allows the assignment of twofold coordinated surface reaction intermediates. DA - 2005/10// PY - 2005/10// DO - 10.1016/j.elecom.2005.07.012 VL - 7 IS - 10 SP - 1077-1081 SN - 1388-2481 KW - silicon etching KW - alkaline solution KW - cathodic bias KW - reaction intermediates KW - accumulation layer ER - TY - JOUR TI - On the microstructure of AlxGa1-xN layers grown on 6H-SiC(0001) substrates AU - Kroger, R. AU - Einfeldt, S. AU - Chierchia, R. AU - Hommel, D. AU - Reitmeier, Z. J. AU - Davis, R. F. AU - Liu, Q. K. K. T2 - Journal of Applied Physics DA - 2005/// PY - 2005/// VL - 97 IS - 8 ER - TY - JOUR TI - Multi-walled carbon nanotube interactions with human epidermal keratinocytes AU - Monteiro-Riviere, NA AU - Nemanich, RJ AU - Inman, AO AU - Wang, YYY AU - Riviere, JE T2 - TOXICOLOGY LETTERS AB - Carbon nanotubes have widespread applications in multiple engineering disciplines. However, little is known about the toxicity or interaction of these particles with cells. Carbon nanotube films were grown using a microwave plasma enhanced chemical vapor deposition system. Human epidermal keratinocytes (HEK) were exposed to 0.1, 0.2, and 0.4 mg/ml of multi-walled carbon nanotubes (MWCNT) for 1, 2, 4, 8, 12, 24 and 48 h. HEK were examined by transmission electron microscopy for the presence of MWCNT. Here we report that chemically unmodified MWCNT were present within cytoplasmic vacuoles of the HEK at all time points. The MWCNT also induced the release of the proinflammatory cytokine interleukin 8 from HEKs in a time dependent manner. These data clearly show that MWCNT, not derivatized nor optimized for biological applications, are capable of both localizing within and initiating an irritation response in a target epithelial cell that composes a primary route of occupational exposure for manufactured nanotubes. DA - 2005/3/15/ PY - 2005/3/15/ DO - 10.1016/j.toxlet.2004.11.004 VL - 155 IS - 3 SP - 377-384 SN - 1879-3169 KW - multi-wall carbon nanotubes KW - human epidermal keratinocytes KW - transmission electron microscopy KW - IL-8 ER - TY - JOUR TI - Investigation of the electrical and optical properties of iridium oxide by reflectance FTIR spectroscopy and density functional theory calculations AU - Brewer, Scott H. AU - Wicaksana, Dwi AU - Maria, Jon-Paul AU - Kingon, Angus I. AU - Franzen, Stefan T2 - Chemical Physics AB - Variable angle reflectance FTIR spectroscopy was used to investigate the optical properties of iridium oxide thin films deposited on glass substrates in the near-IR spectral region. The reflectance was studied as a function of incident angle and wavenumber for p-polarized radiation. The Drude free-electron model along with the Fresnel equations of reflection were utilized to fit the experimental reflectance FTIR data to determine the plasma frequency and electronic scattering time of this conducting metal oxide thin film. These experimental studies were complemented by density functional theory (DFT) calculations of the electronic and optical properties of iridium oxide. The calculations used the crystal structure of iridium oxide with periodic boundary conditions. These theoretical studies yielded the optical band gap, Fermi energy, charge carrier concentration, effective electron mass, plasma frequency and the conduction band orbital character of iridium oxide. The computed dependence of the optical band gap, Fermi energy, charge carrier concentration and the plasma frequency on compression or expansion of the iridium oxide unit cell was investigated. DA - 2005/6// PY - 2005/6// DO - 10.1016/j.chemphys.2004.11.014 VL - 313 IS - 1-3 SP - 25-31 J2 - Chemical Physics LA - en OP - SN - 0301-0104 UR - http://dx.doi.org/10.1016/j.chemphys.2004.11.014 DB - Crossref KW - plasmon frequency KW - conductivity KW - metal oxide KW - band gap ER - TY - JOUR TI - Intersecting basal plane and prismatic stacking fault structures and their formation mechanisms in GaN AU - Bai, J. AU - Huang, X. AU - Dudley, M. AU - Wagner, B. AU - Davis, R. F. AU - Wu, L. AU - Sutter, E. AU - Zhu, Y. AU - Skromme, B. J. T2 - Journal of Applied Physics DA - 2005/// PY - 2005/// VL - 98 IS - 6 ER - TY - JOUR TI - Internal displacement reactions in multicomponent oxides: Part II. Oxide solid solutions of wide composition range AU - Reddy, SNS AU - Leonard, DN AU - Wiggins, LB AU - Jacob, KT T2 - METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE AB - As models of internal displacement reacions in oxide solid solutions, the following reactions were studied at 1273 K as a function of time: $$\begin{gathered} Fe + (Ni_x Mg_{1 - x} )O = Ni + (Fe_x Mg_{1 - x} )O \hfill \\ Fe + (Co_{0.5} Mg_{0.5} )O = Co + (Fe_{0.5} Mg_{0.5} )O \hfill \\ \end{gathered} $$ In both reactions, Ni or Co in the starting oxide is displaced by Fe and the γ-(Ni-Fe) or (Co-Fe) alloy is precipitated. In the reaction zone, composition gradients develop in both product phases, viz., the oxide and the alloy precipitate. The Ni (or Co) concentration of the alloy precipitate increases towards the reaction front. In the product oxide, the “inert” Mg diffuses toward the reaction front along with the Fe, while the Ni (or Co) diffusion is in the opposite direction, towards the Fe/boundary. The shape of the composition profiles for Mg and Fe in the product oxide suggests that cross-coefficient terms in the generalized flux equations contribute significantly to the cation flux. The parabolic rate constants of reactions involving Fe/(Ni x Mg1-x )O decrease by nearly four orders of magnitude when x decreases from 1 to 0.1. DA - 2005/10// PY - 2005/10// DO - 10.1007/s11661-005-0266-1 VL - 36A IS - 10 SP - 2695-2703 SN - 1073-5623 ER - TY - JOUR TI - Internal displacement reactions in multicomponent oxides: Part I. Line compounds with narrow homogeneity range AU - Reddy, SNS AU - Leonard, DN AU - Wiggins, LB AU - Jacob, KT T2 - METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE AB - As a model of an internal displacement reaction involving a ternary oxide “line” compound, the following reaction was studied at 1273 K as a function of time, t: Both polycrystalline and single-crystal materials were used as the starting NiTiO3 oxide. During the reaction, the Ni in the oxide compound is displaced by Fe and it precipitates as a γ-(Ni-Fe) alloy. The reaction preserves the starting ilmenite structure. The product oxide has a constant Ti concentration across the reaction zone, with variation in the concentration of Fe and Ni, consistent with ilmenite composition. In the case of single-crystal NiTiO3 as the starting oxide, the γ alloy has a “layered” structure and the layer separation is suggestive of Liesegang-type precipitation. In the case of polycrystalline NiTiO3 as the starting oxide, the alloy precipitates mainly along grain boundaries, with some particles inside the grains. A concentration gradient exists in the alloy across the reaction zone and the composition is >95 at. pct Ni at the reaction front. The parabolic rate constant for the reaction is k p =1.3 × 10−12 m2 s−1 and is nearly the same for both single-crystal and polycrystalline oxides. DA - 2005/10// PY - 2005/10// DO - 10.1007/s11661-005-0265-2 VL - 36A IS - 10 SP - 2685-2694 SN - 1073-5623 ER - TY - JOUR TI - Homoepitaxial growth of dense ZnO(0001) and ZnO (1120) films via MOVPE on selected ZnO substrates AU - Pierce, J. M. AU - Adekore, B. T. AU - Davis, R. F. AU - Stevie, F. A. T2 - Journal of Crystal Growth DA - 2005/// PY - 2005/// VL - 283 IS - 02-Jan SP - 147-155 ER - TY - JOUR TI - Growth of dense ZnO films via MOVPE on GaN(0001) epilayers using a low/high-temperature sequence AU - Pierce, JM AU - Adekore, BT AU - Davis, RF AU - Stevie, FA T2 - JOURNAL OF CRYSTAL GROWTH AB - Dense zinc oxide thin films have been achieved on GaN(0 0 0 1) epilayers via the repetition of an iterative sequence involving the growth at 480 °C of needles having a decreasing diameter as a function of height followed by the lateral growth from the sidewalls of these needles and coalescence of the growth fronts at 800 °C. Each sequence resulted in a contiguous layer having a thickness of approximately 200 nm. Diethylzinc and UHP oxygen were used as sources of zinc and atomic oxygen, respectively; UHP argon served as both the carrier and the diluent gas. The final growth surface of each densified film contained hexagonal depressions caused by growth among needles of different heights and growth pits that increased in number with an increase in film thickness. These microstructural features were manifest upon and affected the densities and magnitudes of similar features produced in subsequent layers. Triple-axis X-ray diffraction measurements revealed that the orientations of the crystallographic planes and directions within the films mimicked those of the underlying GaN substrate. Concentrations of carbon and hydrogen oscillated throughout the films due to their incorporation primarily within the lower and larger volumes of the needles during each low-temperature deposition of this microstructure. DA - 2005/4/15/ PY - 2005/4/15/ DO - 10.1016/j.jcrysgro.2005.01.054 VL - 277 IS - 1-4 SP - 345-351 SN - 1873-5002 KW - crystal morphology KW - impurities KW - X-ray diffraction KW - organometallic vapor phase deposition KW - ZnO ER - TY - JOUR TI - Ferroelectric response from lead zirconate titanate thin films prepared directly on low-resistivity copper substrates AU - Losego, MD AU - Jimison, LH AU - Ihlefeld, JF AU - Maria, JP T2 - APPLIED PHYSICS LETTERS AB - We demonstrate films of the well-known ferroelectric lead zirconate titanate (PZT) prepared directly on copper foils by chemical solution deposition (CSD). The films exhibit saturating polarization hysteresis, remanent polarization values of 26μC∕cm2, and permittivities of 800; these properties are comparable to those achieved using semiconductor-grade substrates. The preparation methodology is founded upon an understanding of solution chemistry as opposed to conventional gas-phase ∕ condensed-phase equilibrium approaches. By adopting this technique, base-metal compatibility can be achieved using much lower temperatures, and a broader set of devices can be prepared offering intimate contact with high conductivity, easily patternable, or ferromagnetic metals. DA - 2005/4/25/ PY - 2005/4/25/ DO - 10.1063/1.1919388 VL - 86 IS - 17 SP - SN - 0003-6951 ER - TY - JOUR TI - Electrical, structural, and chemical analysis of defects in epitaxial SiGe-based heterostructures AU - Bray, K. R. AU - Zhao, W. AU - Kordas, L. AU - Wise, R. AU - Robinson, M. AU - Rozgonyi, G. T2 - Journal of the Electrochemical Society DA - 2005/// PY - 2005/// VL - 152 IS - 5 SP - C310-315 ER - TY - JOUR TI - Characterization of the piezoelectric properties of Pb0.98Ba0.02(Mg1/3Nb2/3)O-3-PbTiO3 epitaxial thin films AU - Maria, JP AU - Shepard, JF AU - Trolier-McKinstry, S AU - Watkins, TR AU - Payzant, AE T2 - INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY AB - Pb(Mg 1/3 Nb 2/3 )O 3 –PbTiO 3 (PMN–PT) (70/30) thin films were deposited by pulsed laser deposition using two growth strategies: adsorption controlled deposition from lead‐rich targets (∼25–30 mass%) and lower‐temperature deposition ( T d ≤600°C) from targets containing a small amount of excess lead oxide (≤3 mass %). The substrates used were (001) SrRuO 3 /LaAlO 3 . Typical remanent polarization values ranged between 12 and 14 μC/cm 2 for these films. The longitudinal piezoelectric coefficient ( d 33,f ) was measured using in situ four‐circle X‐ray diffraction, and the transverse coefficient ( d 31,f or e 31,f ) was measured using the wafer flexure method. d 33,f and e 31,f coefficients of ∼300–350 pm/V and ∼−11 C/m 2 were calculated, respectively. In general, the piezoelectric coefficients and aging rates were strongly asymmetric, suggesting the presence of a polarization bias. The large, extremely stable piezoelectric response that results from poling parallel to the preferred polarization direction is attractive for miniaturized sensors and actuators. DA - 2005/// PY - 2005/// DO - 10.1111/j.1744-7402.2005.02004.x VL - 2 IS - 1 SP - 51-58 SN - 1744-7402 ER - TY - JOUR TI - Characterization and modeling of AlGaN/GaN MOS capacitor with leakage for large signal transistor modeling AU - Dandu, K AU - Saripalli, Y AU - Braddock, D AU - Johnson, M AU - Barlage, DW T2 - IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS AB - Dual mode AlGaN/GaN metal oxide semiconductor (MOS) heterostructure field-effect transistor (HFET) devices were fabricated and characterized. In HFET mode of operation the devices showed an f T /spl middot/L/sub g/ product of 12GHz/spl middot/μm at Vgs=-2 V. The AlGaN devices showed formation of an accumulation layer under the gate in forward bias and a f T /spl middot/L/sub g/ product of 6GHz/spl middot/μm was measured at Vgs=5 V. A novel piecewise small signal model for the gate capacitance of MOS HFET devices is presented and procedures to extract the capacitance in presence of gate leakage are outlined. The model accurately fits measured data from 45MHz to 10GHz over the entire bias range of operation of the device. DA - 2005/10// PY - 2005/10// DO - 10.1109/LMWC.2005.856680 VL - 15 IS - 10 SP - 664-666 SN - 1531-1309 KW - AlGaN/GaN heterostructure field-effect transistors (HFETs) KW - metal oxide semiconductor (MOS) capacitors KW - modeling ER - TY - JOUR TI - Atomic force microscopy-based experimental setup for studying domain switching dynamics in ferroelectric capacitors AU - Dehoff, C AU - Rodriguez, BJ AU - Kingon, AI AU - Nemanich, RJ AU - Gruverman, A AU - Cross, JS T2 - REVIEW OF SCIENTIFIC INSTRUMENTS AB - This article describes an experimental setup for combined measurements of domain switching dynamics and switching currents in micrometer scale ferroelectric capacitors. The setup is based on a commercial atomic force microscope (AFM) that is equipped with a piezoresponse mode for domain imaging and with a wide bandwidth current amplifier for switching current recording. The setup allows combined domain/current measurements in capacitors as small as 1μm2 with switching times resolved down to 10ns. The incorporation of switching current measurement capability into piezoresponse AFM makes detailed analysis of switching behavior in ferroelectric memory devices possible. DA - 2005/2// PY - 2005/2// DO - 10.1063/1.1850652 VL - 76 IS - 2 SP - SN - 1089-7623 ER - TY - JOUR TI - Ad hoc continuum-atomistic thermostat for modeling heat flow in molecular dynamics simulations AU - Schall, JD AU - Padgett, CW AU - Brenner, DW T2 - MOLECULAR SIMULATION AB - Abstract An ad hoc thermostating procedure that couples a molecular dynamics (MD) simulation and a numerical solution to the continuum heat flow equation is presented. The method allows experimental thermal transport properties to be modeled without explicitly including electronic degrees of freedom in a MD simulation. The method is demonstrated using two examples, heat flow from a constant temperature silver surface into a single crystal bulk, and a tip sliding along a silver surface. For the former it is shown that frictional forces based on the Hoover thermostat applied locally to grid regions of the simulation are needed for effective feedback between the atomistic and continuum equations. For fast tip sliding the thermostat results in less surface heating, and higher frictional and normal forces compared to the same simulation without the thermostat. Keywords: Molecular dynamics simulationMolecular heat flowContinuum-Atomistic ThermostatContinuum heat flow Acknowledgements This work was supported by the Office of Naval Research through grant N00014-04-2006. DA - 2005/4/15/ PY - 2005/4/15/ DO - 10.1080/08927020512331336898 VL - 31 IS - 4 SP - 283-288 SN - 1029-0435 KW - molecular dynamics simulation KW - molecular heat flow KW - continuum-atomistic thermostat KW - continuum ER - TY - JOUR TI - Abrasive micro-blasting to improve surface integrity of electrical discharge machined WC-Co composite AU - Qu, J AU - Shih, AJ AU - Scattergood, RO AU - Luo, J T2 - JOURNAL OF MATERIALS PROCESSING TECHNOLOGY AB - This study investigates the improvement of surface integrity of wire electrical discharge machined (EDM) WC–Co composite by abrasive micro-blasting. The thermally damaged recast layer generated by EDM has craters, cracks, and bubbles, which deteriorate the surface mechanical properties. The micro-blasting, using 6–12 and 4–20 μm size SiC abrasive, enables the removal of the recast layer and is suitable for micro mechanical components. The surface roughness of EDM rough cut WC–Co parts was improved significantly, with the average surface roughness (Ra) dropping down from 1.3 to 0.7 μm. Scanning electron microscope (SEM) was used to examine the evolution change of surface texture and subsurface cross-section of EDM WC–Co workpiece. The SEM micrographs showed that the recast layer was removed efficiently. After 5 s of micro-blasting, surface textures with ridge and cavity patterns were observed on fine and rough cut EDM surfaces, respectively. These surface textures could be correlated to the surface roughness measurement and crater formation in EDM spark erosion. A series of erosion wear experiment was conducted to quantify the weight reduction, calculate the erosion wear rate, and identify the wear mechanism. DA - 2005/8/20/ PY - 2005/8/20/ DO - 10.1016/j.jmatprotec.2004.09.075 VL - 166 IS - 3 SP - 440-448 SN - 1097-6787 KW - micro-blasting KW - EDM KW - surface integrity ER - TY - JOUR TI - A continuum-atomistic method for incorporating Joule heating into classical molecular dynamics simulations AU - Padgett, CW AU - Brenner, DW T2 - MOLECULAR SIMULATION AB - Abstract A hybrid atomistic-continuum method is presented for incorporating Joule heating into large-scale molecular dynamics (MD) simulations. When coupled to a continuum thermostat, the method allows resistive heating and heat transport in metals to be modeled without explicitly including electronic degrees of freedom. Atomic kinetic energies in a MD simulation are coupled via an ad hoc feedback loop to continuum current and heat transfer equations that are solved numerically on a finite difference grid (FDG). For resistive heating, the resistance in each region of the FDG is calculated from the experimental resistivity, atomic density, and average kinetic energy in the MD simulation. A network of resistors is established from which the potential at every FDG region is calculated given an applied voltage. The potential differences and the resistance between connected FDG regions are used to calculate the current between the two points and the heat generated from that current. This information is then added back into the atomic simulation. The method is demonstrated by simulating Joule heating and melting, along with associated changes in current, of single and bundles of metal nanowires, as well as a “pinched” wire under applied strain. Keywords: Joule heatingMolecular simulationMulti-scale modelingElectron wind Acknowledgements This work was funded by a Georgia Tech MURI, which is supported by the Office of Naval Research. Helpful discussions with J. David Schall, George C. Jordan, Doug Irving, and Yanhong Hu are acknowledged. Notes † Handbook where values are taken (CRC Handbook of Chemistry and Physics, 81st edition, CRC Press, New York, (2000).). DA - 2005/9// PY - 2005/9// DO - 10.1080/08927020500262614 VL - 31 IS - 11 SP - 749-757 SN - 1029-0435 KW - Joule heating KW - Molecular simulation KW - Multi-scale modeling KW - Electron wind ER - TY - JOUR TI - Non-crystalline oxides and chalcogenides: A new paradigm based on ab initio quantum chemistry calculations for short range order and properties, and bond-constraint theory for network connectivity, network disruption and chemical phase separation AU - Lucovsky, G. T2 - Journal of Optoelectronics and Advanced Materials DA - 2005/// PY - 2005/// VL - 7 IS - 4 SP - 1691-1706 ER - TY - JOUR TI - Lanthanum silicate gate dielectric stacks with subnanometer equivalent oxide thickness utilizing an interfacial silica consumption reaction AU - Lichtenwalner, DJ AU - Jur, JS AU - Kingon, AI AU - Agustin, MP AU - Yang, Y AU - Stemmer, S AU - Goncharova, LV AU - Gustafsson, T AU - Garfunkel, E T2 - JOURNAL OF APPLIED PHYSICS AB - A silicate reaction between lanthana and silica layers has been utilized to eliminate interfacial silica in metal-insulator-semiconductor devices and to obtain devices with very low equivalent oxide thickness (EOT). This provides a simple process route to interface elimination, while producing a silicate dielectric with a higher temperature stability of the amorphous phase. The La2O3 layers in this study are deposited by reactive evaporation on (001) Si covered by a ∼0.8–1.0-nm-thick SiO2 chemical oxide, and are capped in situ with a Ta gate, followed by a reaction anneal, which lowers the EOT from greater than 1.5 nm for the as-deposited bilayer stack to as low as 0.5 nm. Electron energy-loss spectroscopy and medium-energy ion scattering are used to show that a temperature of 400 °C is sufficient for the formation of the silicate gate dielectric. Gate leakage currents as low as 0.06A∕cm2 are obtained for stacks having an EOT of 0.63 nm, orders of magnitude below that of SiO2 having the same EOT value. Electrical breakdown is observed at applied fields above 16MV∕cm. DA - 2005/7/15/ PY - 2005/7/15/ DO - 10.1063/1.1988967 VL - 98 IS - 2 SP - SN - 1089-7550 ER - TY - JOUR TI - Impact of oxygen on carbon precipitation in polycrystalline ribbon silicon AU - Lu, J. G. AU - Rozgonyi, G. AU - Schonecker, A. AU - Gutjahr, A. AU - Liu, Z. X. T2 - Journal of Applied Physics DA - 2005/// PY - 2005/// VL - 97 IS - 3 ER - TY - JOUR TI - Electromechanical imaging of biological systems with sub-10 nm resolution AU - Kalinin, S. V. AU - Rodriguez, B. J. AU - Jesse, S. AU - Thundat, T. AU - Gruverman, A. T2 - Applied Physics Letters DA - 2005/// PY - 2005/// VL - 87 IS - 5 ER - TY - JOUR TI - Domain growth kinetics in lithium niobate single crystals studied by piezoresponse force microscopy AU - Rodriguez, BJ AU - Nemanich, RJ AU - Kingon, A AU - Gruverman, A AU - Kalinin, SV AU - Terabe, K AU - Liu, XY AU - Kitamura, K T2 - APPLIED PHYSICS LETTERS AB - The kinetics of sidewise domain growth in an inhomogeneous electric field has been investigated in stoichiometric LiNbO3 single crystals by measuring the lateral domain size as a function of the voltage pulse magnitude and duration using piezoresponse force microscopy. The domain size increases linearly with the voltage magnitude suggesting that the domain size is kinetically limited in a wide range of pulse magnitudes and durations. In spite of that, the written domains exhibit strong retention behavior. It is suggested that the switching behavior can be described by the universal scaling curve. Domain kinetics can be described as an activation process by calculating the field distribution using the charged sphere model under the assumption of an exponential field dependence of the wall velocity. The activation energy is found to be a function of the external field. DA - 2005/1/3/ PY - 2005/1/3/ DO - 10.1063/1.1845594 VL - 86 IS - 1 SP - SN - 1077-3118 ER - TY - JOUR TI - Controlled foaming of polymer films through restricted surface diffusion and the addition of nanosilica particles or CO2-philic surfactants AU - Siripurapu, S AU - DeSimone, JM AU - Khan, SA AU - Spontak, RJ T2 - MACROMOLECULES AB - Synergistic use of surface barriers and nanoscale additives is investigated as alternate means by which to promote bubble nucleation in, and thus improve the porosity of, poly(methyl methacrylate) (PMMA) thin films (i) constrained between impenetrable plates, (ii) modified with either nanosilica particles, commercial short-chain fluorosurfactants, or designer CO2-philic block/graft copolymers, and (iii) exposed to high-pressure CO2. Resultant foamed films exhibit a vast array of micro/mesocellular morphologies in the presence of supercritical, as well as liquid, CO2 and demonstrate that copolymer micelles afford better control over bubble nucleation (with pore cell densities, N, approaching 1012 cells/cm3) relative to hard nonporous nanoparticles, which alone increase N by more than 2 orders of magnitude at low CO2 pressures. Incorporation of these nanoscale additives in a surface-constrained polymer matrix serves to enhance foaming through concurrent restriction of CO2 diffusion, heterogeneous nucleation of CO2 bubbles, and/or reduced interfacial tension between PMMA and CO2. DA - 2005/3/22/ PY - 2005/3/22/ DO - 10.1021/ma047991b VL - 38 IS - 6 SP - 2271-2280 SN - 1520-5835 ER - TY - JOUR TI - Step-controlled strain relaxation in the vicinal surface epitaxy of nitrides AU - Huang, X. R. AU - Bai, J. AU - Dudley, M. AU - Wagner, B. AU - Davis, R. F. AU - Zhu, Y. T2 - Physical Review Letters DA - 2005/// PY - 2005/// VL - 95 IS - 8 ER - TY - JOUR TI - Self-organized nanoscale Ge dots and dashes on SiGe/Si superlattices AU - Fitting, L AU - Ware, ME AU - Haywood, , JR AU - Walter, JJH AU - Nemanich, RJ T2 - JOURNAL OF APPLIED PHYSICS AB - This study explores the self-organization of Ge nanostructures on SiGe/Si superlattices grown on Si substrates with the surface normal tilted from (001) towards (111) by up to 25°. Prior studies found two-dimensional ordering of Ge dots on nominally flat Si(001) surfaces with a very homogeneous size distribution. Our results show that the Ge islands are less ordered for tilted Si(001) substrates. For substrates with a miscut of 25°, Ge dots nucleate on top of the ripples that form approximately perpendicular to the [1-10]Si direction, i.e., perpendicular to the step direction. Additionally, we observe the formation of Ge dashes, which align preferentially along the [1-10]Si direction. DA - 2005/7/15/ PY - 2005/7/15/ DO - 10.1063/1.1993751 VL - 98 IS - 2 SP - SN - 1089-7550 ER - TY - JOUR TI - Self-organization and the physics of glassy networks AU - Boolchand, P AU - Lucovsky, G AU - Phillips, JC AU - Thorpe, MF T2 - PHILOSOPHICAL MAGAZINE AB - Network glasses are the physical prototype for many self-organized systems, ranging from proteins to computer science. Conventional theories of gases, liquids and crystals do not account for the strongly material-selective character of the glass-forming tendency, the phase diagrams of glasses or their optimizable properties. A new topological theory, only 25 years old, has succeeded where conventional theories have failed. It shows that (probably all slowly quenched) glasses, including network glasses, are the result of the combined effects of a few simple mechanisms. These glass-forming mechanisms are topological in nature and have already been identified for several important glasses, including chalcogenide alloys, silicates (window glass and computer chips) and proteins. DA - 2005/11/11/ PY - 2005/11/11/ DO - 10.1080/14786430500256425 VL - 85 IS - 32 SP - 3823-3838 SN - 1478-6443 ER - TY - JOUR TI - Seeded growth of bulk AlN crystals and grain evolution in polycrystalline AlN boules AU - Noveski, V. AU - Schlesser, R. AU - Raghothamachar, B. AU - Dudley, M. AU - Mahajan, S. AU - Beaudoin, S. AU - Sitar, Z. T2 - Journal of Crystal Growth AB - Large AlN crystals were grown by powder sublimation in a nitrogen atmosphere at low supersaturation and growth rates of 0.1–0.3 mm/h. The starting deposition surface was a sintered TaC disc. An appropriate adjustment of the system pressure and source-seed temperature gradient during the early stages of growth allowed epitaxial re-growth on AlN seeds that had been exposed to air. Single-crystalline AlN grains of 1 cm in size were achieved through multiple sublimation growth runs conducted at P=500Torr and growth temperatures of 2050–2150 °C. Elemental analysis of impurities in the grown AlN boules confirmed low oxygen contamination levels of ∼1019/cm3. No discontinuities were introduced in the structural defect distribution in the individual single-crystalline grains by the multiple re-growth steps. Absence of preferred growth directions of grains suggest the epitaxial re-growth process is suitable for seeded single-crystal growth in any orientation. DA - 2005/5// PY - 2005/5// DO - 10.1016/j.jcrysgro.2004.12.027 VL - 279 IS - 1-2 SP - 13-19 J2 - Journal of Crystal Growth LA - en OP - SN - 0022-0248 UR - http://dx.doi.org/10.1016/j.jcrysgro.2004.12.027 DB - Crossref KW - bulk AlN KW - single crystal KW - seeded growth KW - sublimation growth ER - TY - JOUR TI - P-type doping utilizing nitrogen and Mn doping of ZnO using MOCVD for ultraviolet lasers and spintronic applications AU - Egerton, EJ AU - Sood, AK AU - Singh, R AU - Puri, YR AU - Davis, RF AU - Pierce, J AU - Look, DC AU - Steiner, T T2 - JOURNAL OF ELECTRONIC MATERIALS DA - 2005/6// PY - 2005/6// DO - 10.1007/s11664-005-0048-y VL - 34 IS - 6 SP - 949-952 SN - 1543-186X KW - ZnO KW - p-type KW - doping ER - TY - JOUR TI - NICE: an instrument for direct mass spectrometric measurement of interstellar neutral gas AU - Wieser, M AU - Wurz, P AU - Bochsler, P AU - Moebius, E AU - Quinn, J AU - Fuselier, SA AU - Ghielmetti, A AU - DeFazio, JN AU - Stephen, TM AU - Nemanich, RJ T2 - MEASUREMENT SCIENCE AND TECHNOLOGY AB - The direct measurement of the neutral interstellar gas requires a very sensitive neutral particle imaging instrument in the energy range of 10 eV–1000 eV. For successful detection and identification, the neutral particles have to be ionized first, which will be accomplished via surface ionization. This method is successfully employed in the Low Energy Neutral Atom imager (LENA) instrument on the IMAGE spacecraft launched on 25 March 2000, which still operates well. We present the laboratory prototype of the Neutral Interstellar Composition Experiment (NICE), a neutral particle mass spectrometer dedicated to the measurement of interstellar gas, and will discuss its instrumental characteristics. Performance is evaluated with emphasis on the neutral to negative ion conversion for hydrogen and oxygen and the collection of these ions by the mass spectrometer. Measurements of the detection efficiency of the prototype for primary neutral hydrogen and oxygen atoms are presented. Several conversion surfaces, conductive and insulating, were investigated and all are potential candidates for a next generation neutral particle imaging instrument. DA - 2005/8// PY - 2005/8// DO - 10.1088/0957-0233/16/8/019 VL - 16 IS - 8 SP - 1667-1676 SN - 1361-6501 KW - interstellar medium KW - energetic neutral atoms KW - surface ionization KW - mass spectrometry KW - imaging neutral atom detector ER - TY - JOUR TI - Low-temperature resistance anomaly at SrTiO3 grain boundaries: Evidence for an interface-induced phase transition AU - Shao, R. AU - Chisholm, M. F. AU - Duscher, G. AU - Bonnell, D. A. T2 - Physical Review Letters DA - 2005/// PY - 2005/// VL - 95 IS - 19 ER - TY - JOUR TI - Local strain, defects, and crystallographic tilt in GaN(0001) layers grown by maskless pendeo-epitaxy from x-ray microdiffraction AU - Barabash, R. I. AU - Ice, G. E. AU - Liu, W. AU - Einfeldt, S. AU - Roskowski, A. M. AU - Davis, R. F. T2 - Journal of Applied Physics DA - 2005/// PY - 2005/// VL - 97 IS - 1 ER - TY - JOUR TI - Investigation of the mechanism of polarization switching in ferroelectric capacitors by three- dimensional piezoresponse force microscopy AU - Rodriguez, BJ AU - Gruverman, A AU - Kingon, AI AU - Nemanich, RJ AU - Cross, JS T2 - APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING AB - A mechanism for the switching behavior of (111)-oriented Pb(Zr,Ti)O3-based 1×1.5 μm2 capacitors has been investigated using three-dimensional piezoresponse force microscopy (3D-PFM). A combination of vertical and lateral piezoresponse force microscopy (VPFM and LPFM) has been used to map the out-of-plane and the in-plane components of the polarization. The three-dimensional polarization distribution was reconstructed by quantitative analysis of the PFM amplitude images of poled PZT capacitors while taking into account contrast variations in the PFM phase images. The switching behavior of the capacitors was determined by comparison of the static domain patterns in the same capacitors after both positive and negative poling. While 180° degree switching was observed, surprisingly, the switching process was dominated by 90° polarization vector rotation. Furthermore, central regions of the capacitors were characterized by the presence of charged domain boundaries, which could lead to imprint (preference of one polarization state over another). DA - 2005/1// PY - 2005/1// DO - 10.1007/s00339-004-2925-2 VL - 80 IS - 1 SP - 99-103 SN - 1432-0630 ER - TY - JOUR TI - Electrical transport in ZnO(1-delta)films: Transition from band-gap insulator to Anderson localized insulator (vol 96, pg 3827, 2004) AU - Tiwari, A. AU - Jin, C. AU - Narayan, J. AU - Park, M. T2 - Journal of Applied Physics DA - 2005/// PY - 2005/// VL - 97 IS - 5 ER - TY - JOUR TI - Effects of preparation procedure and electric field frequency on the dielectric constants and electrorheology of a zeolite/silicone oil suspension AU - McNeish, D AU - Jung, K AU - Balik, CM AU - Conrad, H T2 - INTERNATIONAL JOURNAL OF MODERN PHYSICS B AB - Determined were the effects of preparation procedure and electric field frequency f = dc to 10 5 Hz on the dielectric constants and ER response (shear rate [Formula: see text]) of a suspension in silicone oil of 23 wt.% zeolite particles originally containing 19 wt.% H 2 O . Heating the oil and the zeolite particles at 110°C both prior to, and following, mixing decreased the conductivity of the suspension more than simply heating the suspension following mixing. The double heating procedure reduced the complex dielectric constant [Formula: see text] of the particles and the complex mismatch parameter β*. The ER shear stress τ E was proportional to [Formula: see text] for the single heating and [Formula: see text] for the double heating, where [Formula: see text] is the complex dielectric constant of the silicone oil. The lower exponent corresponds to a higher water content and in turn higher conductivity of the suspension. Erratic ER response occurred for f =10 Hz in tests with [Formula: see text], but not in tests with [Formula: see text]. DA - 2005/4/10/ PY - 2005/4/10/ DO - 10.1142/s0217979205030050 VL - 19 IS - 7-9 SP - 1191-1197 SN - 1793-6578 ER - TY - JOUR TI - Applications of free-electron lasers in the biological and material sciences AU - Edwards, GS AU - Allen, SJ AU - Haglund, RF AU - Nemanich, RJ AU - Redlich, B AU - Simon, JD AU - Yang, WC T2 - PHOTOCHEMISTRY AND PHOTOBIOLOGY AB - Free-Electron Lasers (FELs) collectively operate from the terahertz through the ultraviolet range and via intracavity Compton backscattering into the X-ray and gamma-ray regimes. FELs are continuously tunable and can provide optical powers, pulse structures and polarizations that are not matched by conventional lasers. Representative research in the biological and biomedical sciences and condensed matter and material research are described to illustrate the breadth and impact of FEL applications. These include terahertz dynamics in materials far from equilibrium, infrared nonlinear vibrational spectroscopy to investigate dynamical processes in condensed-phase systems, infrared resonant-enhanced multiphoton ionization for gas-phase spectroscopy and spectrometry, infrared matrix-assisted laser-desorption–ionization and infrared matrix-assisted pulsed laser evaporation for analysis and processing of organic materials, human neurosurgery and ophthalmic surgery using a medical infrared FEL and ultraviolet photoemission electron microscopy for nanoscale characterization of materials and nanoscale phenomena. The ongoing development of ultraviolet and X-ray FELs are discussed in terms of future opportunities for applications research. DA - 2005/// PY - 2005/// DO - 10.1562/2004-11-08-IR-363R.1 VL - 81 IS - 4 SP - 711-735 SN - 1751-1097 ER - TY - JOUR TI - Aluminum nitride thin films on an LTCC substrate AU - Lee, JW AU - Cuomo, JJ AU - Cho, YS AU - Keusseyan, RL T2 - JOURNAL OF THE AMERICAN CERAMIC SOCIETY AB - Aluminum nitride thin films deposited on a low‐temperature co‐fired ceramics substrate by reactive magnetron sputtering were investigated with regard to their crystal orientation and microstructural characteristics. Strong c ‐axis orientations of AlN thin films were observed when either a higher deposition temperature or an RF bias was adopted. This orientation was believed to be responsible for the high thermal conductivity of 26 W/mK for the AlN films deposited at 700°C under 25‐W bias. Photoluminescence spectrum in the wavelength range of 350–650 nm was analyzed to prove the involvement of potential oxygen‐related defects in the thin films. DA - 2005/7// PY - 2005/7// DO - 10.1111/j.1551-2916.2005.00250.x VL - 88 IS - 7 SP - 1977-1980 SN - 1551-2916 ER - TY - JOUR TI - White X-ray microbeam analysis of strain and crystallographic tilt in GaN layers grown by maskless pendeoepitaxy AU - Barabash, R. I. AU - Ice, G. E. AU - Liu, W. AU - Einfeldt, S. AU - Hommel, D. AU - Roskowski, A. M. AU - Davis, R. F. T2 - Physica Status Solidi. A, Applications and Materials Science DA - 2005/// PY - 2005/// VL - 202 IS - 5 SP - 732-738 ER - TY - JOUR TI - Structure and stability of columnar cyclomaltooctaose (gamma-cyclodextrin) hydrate AU - Hunt, MA AU - Rusa, CC AU - Tonelli, AE AU - Balik, CM T2 - CARBOHYDRATE RESEARCH AB - Rapid recrystallization of cyclomaltooctaose (gamma-cyclodextrin, gamma-CD) from aqueous solution resulted in formation of a columnar structure with only water as the guest molecule. Upon vacuum drying at 90 degrees C for 15 h, gamma-CD, which was initially in the columnar structure, became amorphous. Complementary water vapor sorption and wide-angle X-ray diffractometry experiments were performed on columnar gamma-CD in its vacuum dried and as-precipitated states to elucidate its stability in humid environments and the crystal structure present at varying sorption levels. These experiments show that both types of gamma-CD transform to the cage crystal structure upon exposure to water vapor at 40 degrees C and with an activity of 1.0. Sorption equilibrium is reached long before the crystal structure transformation is complete, indicating that a significant amount of molecular mobility exists in the various hydrated gamma-CD crystal structures. DA - 2005/7/4/ PY - 2005/7/4/ DO - 10.1016/j.carres.2005.03.021 VL - 340 IS - 9 SP - 1631-1637 SN - 1873-426X KW - gamma-cyclodextrin KW - water vapor sorption KW - wide-angle X-ray diffraction KW - phase transformation ER - TY - JOUR TI - Structural, microstructural, and electrical properties of gold films and Schottky contacts on remote plasma-cleaned, n-type ZnO{0001} surfaces AU - Coppa, BJ AU - Fulton, CC AU - Kiesel, SM AU - Davis, RF AU - Pandarinath, C AU - Burnette, JE AU - Nemanich, RJ AU - Smith, DJ T2 - JOURNAL OF APPLIED PHYSICS AB - Current–voltage measurements of Au contacts deposited on ex situ cleaned, n-type ZnO(0001) [(0001¯)] surfaces showed reverse bias leakage current densities of ∼0.01(∼0.1)A∕cm2 at 4.6 (3.75) V reverse bias and ideality factors &gt;2 (both surfaces) before sharp, permanent breakdown (soft breakdown). This behavior was due primarily to the presence of (1.6–2.0)±0.1[(0.7–2.6)±0.1] monolayers (ML) of hydroxide, which forms an electron accumulation layer and increases the surface conductivity. In situ remote plasma cleaning of the (0001) [(0001¯)] surfaces using a 20vol%O2∕80vol%He mixture for the optimized temperatures, times, and pressure of 550±20°C(525±20°C), 60 (30) min, and 0.050 Torr reduced the thickness of the hydroxide layer to ∼0.4±0.1ML and completely eliminated all detectable hydrocarbon contamination. Subsequent cooling of both surfaces in the plasma ambient resulted in the chemisorption of oxygen and a change from 0.2 eV of downward band bending for samples cooled in vacuum to 0.3 eV of upward band bending indicative of the formation of a depletion layer of lower surface conductivity. Cooling in either ambient produced stoichiometric ZnO{0001} surfaces having an ordered crystallography as well as a step-and-terrace microstructure on the (0001¯) surface; the (0001) surface was without distinctive features. Sequentially deposited, unpatterned Au films, and presumably the rectifying gold contacts, initially grew on both surfaces cooled in the plasma ambient via the formation of islands that subsequently coalesced, as indicated by calculations from x-ray photoelectron spectroscopy data and confirmed by transmission electron microscopy. Calculations from the current–voltage data of the best contacts revealed barrier heights on the (0001) [(0001¯)] surfaces of 0.71±0.05(0.60±0.05)eV, a saturation current density of (4±0.5)×10−6A∕cm2(2.0±0.5×10−4A∕cm2), a lower value of n=1.17±0.05(1.03±0.05), a significantly lower leakage current density of ∼1.0×10−4A∕cm2(∼91×10−9A∕cm2) at 8.5 (7.0) V reverse bias prior to sharp, permanent breakdown (soft breakdown). All measured barrier heights were lower than the predicted Schottky–Mott value of 1.0 eV, indicating that the interface structure and the associated interface states affect the Schottky barrier. However, the constancy in the full width at half maximum of the core levels for Zn 2p(1.9±0.1eV) and O 1s(1.5±0.1eV), before and after sequential in situ Au depositions, indicated an abrupt, unreacted Au∕ZnO(0001) interface. Transmission electron microscopy confirmed the abruptness of an epitaxial interface. Annealing the contacts on the (0001) surface to 80±5 and 150±5°C resulted in decreases in the ideality factors to 1.12±0.05 and 1.09±0.05 and increases in saturation current density to 9.05 and 4.34μA∕cm2, the barrier height to 0.82±0.5 and 0.79±0.5eV, and in the leakage current densities to ∼2×10−3A∕cm2 at 6 V and ∼20×10−3A∕cm2 at 7 V, respectively. DA - 2005/5/15/ PY - 2005/5/15/ DO - 10.1063/1.1898436 VL - 97 IS - 10 SP - SN - 1089-7550 ER - TY - JOUR TI - Photo-electron emission and atomic force microscopies of the hydrogen etched 6H-SiC(0001) surface and the initial growth of GaN and AlN AU - Hartman, JD AU - Naniwae, K AU - Petrich, C AU - Nemanich, R AU - Davis, RF T2 - APPLIED SURFACE SCIENCE AB - Photo-emission electron microscopy (PEEM) and atomic force microscopy (AFM) have been used to characterize the surfaces of hydrogen etched 6H-SiC(0 0 0 1) wafers and the microstructure of the initial stages of growth of GaN and AlN on these surfaces via molecular beam epitaxy. The PEEM images were obtained using a free electron laser as the photon source. A stepped structure was evident in these images of the surfaces etched at 1600–1700 °C for 15 min. Comparison with the AFM images revealed that emission was occurring from the intersection of the steps and the terraces. Images of the initial stages of deposition of the GaN thin films at 700 and 800 °C revealed three-dimensional island growth. The degree of coalescence of these films was dependent upon the step structure: regions containing steps having unit cell height exhibited complete or nearly complete coalescence; regions containing steps with half unit cell height showed voids in the films parallel to the steps. PEEM of the initial stages of growth of AlN revealed immediate nucleation and rapid coalescence during deposition at 900 °C, except in areas on the substrate surface containing steps having half unit cell height. Incomplete coalescence and pits were also observed in the latter areas. DA - 2005/4/15/ PY - 2005/4/15/ DO - 10.1016/j.apsusc.2004.09.021 VL - 242 IS - 3-4 SP - 428-436 SN - 0169-4332 KW - photo-emission electron microscopy KW - gallium nitride KW - aluminum nitride KW - silicon carbide KW - molecular beam epitaxy KW - stepped single crystal surfaces ER - TY - JOUR TI - Photo electron emission microscopy of polarity-patterned materials AU - Yang, WC AU - Rodriguez, BJ AU - Gruverman, A AU - Nemanich, RJ T2 - JOURNAL OF PHYSICS-CONDENSED MATTER AB - This study presents variable photon energy photo electron emission microscopy (PEEM) of polarity-patterned epitaxial GaN films, and ferroelectric LiNbO3 (LNO) single crystals and PbZrTiO3 (PZT) thin films. The photo electrons were excited with spontaneous emission from the tunable UV free electron laser (FEL) at Duke University. We report PEEM observation of polarity contrast and measurement of the photothreshold of each polar region of the materials. Fo ra cleaned GaN film with laterally patterned Ga- and N-face polarities, we found a higher photoelectric yield from the N-face regions compared with the Ga-face regions. Through the photon energy dependent contrast in the PEEM images of the surfaces, we can deduce that the threshold of the N-face region is less than ∼4. 9e V while that of the Ga-face regions is greater than 6.3 eV. In both LNO and PZT, bright emission was detected from the negatively poled domains, indicating that the emission threshold of the negative domain is lower than that of the positive domain. For LNO, the measured photothreshold was ∼4. 6e V at thenegative domain and ∼6. 2e V at thepositive domain, while for PZT, the threshold of the negative domain was less than 4.3 eV. Moreover, PEEM observation of the PZT surface at elevated temperatures displayed that the domain contrast disappeared near the Curie temperature of ∼300 ◦ C. The PEEM polarity contrast of the polar materials is discussed in terms of internal screening from free carriers and defect sa nd the external screening due to adsorbed ions. DA - 2005/4/27/ PY - 2005/4/27/ DO - 10.1088/0953-8984/17/16/012 VL - 17 IS - 16 SP - S1415-S1426 SN - 1361-648X ER - TY - JOUR TI - Nanoscale polarization relaxation in a polycrystalline ferroelectric thin film: Role of local environments AU - Nagarajan, V. AU - Aggarwal, S. AU - Gruverman, A. AU - Ramesh, R. AU - Waser, R. T2 - Applied Physics Letters DA - 2005/// PY - 2005/// VL - 86 IS - 26 ER - TY - JOUR TI - Hollow to bamboolike internal structure transition observed in carbon nanotube films AU - Wang, YY AU - Gupta, S AU - Nemanich, RJ AU - Liu, ZJ AU - Qin, LC T2 - JOURNAL OF APPLIED PHYSICS AB - The transition of the internal structure in microwave chemical-vapor-deposited carbon nanotubes is investigated using scanning electron microscopy and high-resolution transmission electron microscopy. By controlling the thickness of the iron catalyst layer, a sequence of carbon nanotube films was obtained with diameters ranging from a few nanometers to over 100nm. Experiments have established that by continuous reduction of the Fe layer thickness to &lt;1nm, single- and double-wall carbon nanotube films can be produced, whereas for an Fe film thickness &gt;1nm, multiwall carbon nanotube films can be synthesized. It was also found that for an Fe thickness ⩾5nm, interlayers (i.e., bamboolike or periodically compartmentalized nanotubes) were formed, while for an iron thickness &lt;2nm the tubes were primarily hollow. For an intermediate Fe thickness the internal structure of the carbon nanotubes was a mixture of hollow and bamboolike. A growth model which considers bulk and surface diffusions of carbon into and∕or onto the Fe catalyst surface is proposed to describe this transition and the internal periodic structure. DA - 2005/7/1/ PY - 2005/7/1/ DO - 10.1063/1.1946198 VL - 98 IS - 1 SP - SN - 1089-7550 ER - TY - JOUR TI - Fabrication of wafer scale, aligned sub-25 nm nanowire and nanowire templates using planar edge defined alternate layer process AU - Sonkusale, , SR AU - Amsinck, CJ AU - Nackashi, DP AU - Di Spigna, NH AU - Barlage, D AU - Johnson, M AU - Franzon, PD T2 - PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES AB - We have demonstrated a new planar edge defined alternate layer (PEDAL) process to make sub-25 nm nanowires across the whole wafer. The PEDAL process is useful in the fabrication of metal nanowires directly onto the wafer by shadow metallization and has the ability to fabricate sub-10 nm nanowires with 20 nm pitch. The process can also be used to make templates for the nano-imprinting with which the crossbar structures can be fabricated. The process involves defining the edge by etching a trench patterned by conventional i-line lithography, followed by deposition of alternating layers of silicon nitride and crystallized a-Si. The thickness of these layers determines the width and spacing of the nanowires. Later the stack is planarized to the edge of the trench by spinning polymer Shipley 1813 and then dry etching the polymer, nitride and polysilicon stack with non-selective RIE etch recipe. Selective wet etch of either nitride or polysilicon gives us the array of an aligned nanowires template. After shadow metallization of the required metal, we get metal nanowires on the wafer. The process has the flexibility of routing the nanowires around the logic and memory modules all across the wafer. The fabrication facilities required for the process are readily available and this process provides the great alternative to existing slow and/or costly nanowire patterning techniques. DA - 2005/7// PY - 2005/7// DO - 10.1016/j.physe.2005.01.010 VL - 28 IS - 2 SP - 107-114 SN - 1873-1759 KW - nanowire KW - nanoimprinting KW - mold KW - template KW - interconnects KW - nanotechnology ER - TY - JOUR TI - Fabrication and thermal evaluation of silicon on diamond wafers AU - Aleksov, A AU - Wolter, SD AU - Prater, JT AU - Sitar, Z T2 - JOURNAL OF ELECTRONIC MATERIALS DA - 2005/7// PY - 2005/7// DO - 10.1007/s11664-005-0100-y VL - 34 IS - 7 SP - 1089-1094 SN - 0361-5235 KW - diamond KW - silicon KW - silicon on insulator (SOI) KW - thermal ER - TY - JOUR TI - Effect of UV/VUV enhanced RTP on process variation and device performance of metal gate high-kappa gate stacks for the sub-90-nm CMOS regime AU - Damjanovic, D. AU - Bolla, H. K. AU - Singh, R. AU - Poole, K. F. AU - Senter, H. F. AU - Narayan, Jagdish T2 - IEEE Transactions on Semiconductor Manufacturing AB - We show that UV/VUV-enhanced rapid thermal processing (RTP) in combination with single-wafer processing using a single tool for the fabrication of metal gate/high-/spl kappa/ dielectric gate stacks not only improves overall device performance, but also leads to a significant reduction in process variation at the front end of the CMOS process flow for the sub-90-nm technology node. The gate stacks were fabricated under various UV/VUV conditions. Gate stacks processed under UV/VUV radiation during all processing steps displayed low leakage currents of the order of 10/sup -11/ A/cm/sup 2/. It is shown that the Al-Al/sub 2/O/sub 3/-Si gate stacks processed under UV/VUV conditions also display the lowest variations both in mean leakage current and mean capacitance, as compared to devices where UV/VUV was not used for all the processing steps. Therefore, it can be see that reliance on successive corrective iterations common to automatic process control or standard design simulation can be reduced significantly. As a result, UV/VUV-enhanced RTP has the potential to reduce the effect of process variations on overall device performance, thereby making the overall process more cost effective and time efficient and therefore improving yield and device reliability. DA - 2005/// PY - 2005/// DO - 10.1109/TSM.2004.841823 VL - 18 IS - 1 SP - 55–62 ER - TY - JOUR TI - Diffusion-controlled reactive coupling at polymer-polymer interfaces AU - Harton, SE AU - Stevie, FA AU - Ade, H T2 - MACROMOLECULES AB - ADVERTISEMENT RETURN TO ISSUECommunication to the...Communication to the EditorNEXTDiffusion-Controlled Reactive Coupling at Polymer−Polymer InterfacesS. E. Harton, F. A. Stevie, and H. AdeView Author Information Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695; Analytical Instrumentation Facility, North Carolina State University, Raleigh, North Carolina 27695; and Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 Cite this: Macromolecules 2005, 38, 9, 3543–3546Publication Date (Web):April 2, 2005Publication History Received15 December 2004Revised9 March 2005Published online2 April 2005Published inissue 1 May 2005https://doi.org/10.1021/ma047421bCopyright © 2005 American Chemical SocietyRequest reuse permissionsArticle Views310Altmetric-Citations32LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Copolymers,Diffusion,Interfaces,Layers,Polymers Get e-Alerts DA - 2005/5/3/ PY - 2005/5/3/ DO - 10.1021/ma047421b VL - 38 IS - 9 SP - 3543-3546 SN - 0024-9297 ER - TY - JOUR TI - Design of an RF-heated bulk AlN growth reactor: Induction heating and heat transfer modeling AU - Wu, B AU - Noveski, V AU - Zhang, H AU - Schlesser, R AU - Mahajan, S AU - Beaudoin, S AU - Sitar, Z T2 - CRYSTAL GROWTH & DESIGN AB - An induction heating and thermal model was developed to design an inductively heated reaction system for bulk AlN crystal growth by powder sublimation. The electromagnetic field and induction heat generation were calculated using the Maxwell equations, and transient temperature distribution was simulated considering conduction and radiation between various components. The complex dependence of the temperature distribution on the radio frequency (RF) coil current and position was demonstrated by numerical studies. A custom-designed high-temperature reactor was constructed and tested. To provide proper temperature control during envisioned sublimation growth, the response of temperature and temperature difference of the bottom and top external surfaces of the growth crucible to power consumption and coil position was measured. The experimental results corresponded well with the simulated temperature responses. DA - 2005/// PY - 2005/// DO - 10.1021/cg050014m VL - 5 IS - 4 SP - 1491-1498 SN - 1528-7505 ER - TY - JOUR TI - Copper compatible barium titanate thin films for embedded passives AU - Ihlefeld, J AU - Laughlin, B AU - Hunt-Lowery, A AU - Borland, W AU - Kingon, A AU - Maria, JP T2 - JOURNAL OF ELECTROCERAMICS DA - 2005/3// PY - 2005/3// DO - 10.1007/s10832-005-0866-6 VL - 14 IS - 2 SP - 95-102 SN - 1573-8663 KW - barium titanate KW - copper KW - ferroelectric KW - film KW - capacitor ER - TY - JOUR TI - The effects of oxygen, nitrogen, and hydrogen annealing on Mg acceptors in GaN as monitored by electron paramagnetic resonance spectroscopy AU - Matlock, DM AU - Zvanut, ME AU - Wang, HY AU - Dimaio, , JR AU - Davis, RF AU - Van Nostrand, JE AU - Henry, RL AU - Koleske, D AU - Wickenden, A T2 - JOURNAL OF ELECTRONIC MATERIALS DA - 2005/1// PY - 2005/1// DO - 10.1007/s11664-005-0177-3 VL - 34 IS - 1 SP - 34-39 SN - 1543-186X KW - electron paramagnetic resonance (EPR) KW - Mg doped KW - GaN KW - annealing KW - hydrogen KW - oxygen ER - TY - JOUR TI - Tensile properties of in situ consolidated nanocrystalline Cu AU - Cheng, S AU - Ma, E AU - Wang, YM AU - Kecskes, LJ AU - Youssef, KM AU - Koch, CC AU - Trociewitz, UP AU - Han, K T2 - ACTA MATERIALIA AB - We have prepared Cu powders with nanocrystalline grain sizes via ball milling at liquid nitrogen temperature. An in situ consolidation technique was used to produce fully dense nanocrystalline Cu samples centimeters in lateral dimensions and about one millimeter in thickness. We report a much improved combination of tensile strength and ductility, over the tensile properties of other nanocrystalline Cu materials documented in the literature. We also demonstrate the elevated strain rate sensitivity and strong temperature dependence of the flow stress and explain the results in terms of the thermally activated deformation mechanisms operative in the nanocrystalline grains. The nearly perfectly plastic behavior and shear localization observed are discussed and compared with the strain hardening behavior and deformation modes known for other nanocrystalline metals. DA - 2005/3// PY - 2005/3// DO - 10.1016/j.actamat.2004.12.005 VL - 53 IS - 5 SP - 1521-1533 SN - 1873-2453 KW - nanocrystalline KW - copper KW - mechanical property KW - consolidation KW - deformation mechanism ER - TY - JOUR TI - Microcontact patterning of ruthenium gate electrodes by selective area atomic layer deposition AU - Park, KJ AU - Doub, JM AU - Gougousi, T AU - Parsons, GN T2 - APPLIED PHYSICS LETTERS AB - Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation K. J. Park, J. M. Doub, T. Gougousi, G. N. Parsons; Microcontact patterning of ruthenium gate electrodes by selective area atomic layer deposition. Appl. Phys. Lett. 31 January 2005; 86 (5): 051903. https://doi.org/10.1063/1.1852079 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioApplied Physics Letters Search Advanced Search |Citation Search DA - 2005/1/31/ PY - 2005/1/31/ DO - 10.1063/1.1852079 VL - 86 IS - 5 SP - SN - 0003-6951 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000227144700016&KeyUID=WOS:000227144700016 ER - TY - JOUR TI - Lead zirconate titanate thin films directly on copper electrodes for ferroelectric, dielectric and piezoelectric applications AU - Kingon, AI AU - Srinivasan, S T2 - NATURE MATERIALS DA - 2005/3// PY - 2005/3// DO - 10.1038/nmat1334 VL - 4 IS - 3 SP - 233-237 SN - 1476-4660 ER - TY - JOUR TI - Kinematic, stress, and hardening analysis in finite double slip AU - Havner, KS AU - Yu, PG T2 - INTERNATIONAL JOURNAL OF PLASTICITY AB - A kinematic, stress, and hardening analysis of finite double slip in fcc crystals under axial loading is presented. The relative amounts of slip in classic 1925 experiments by Taylor and Elam (determined analytically in [Int. J. Plasticity 9 (1993) 159–179] by comparing theoretical and experimental cones of unextended directions), together with load-extension data and other measurements, are used to calculate resolved shear stress vs. slip curves and assess predictions of several finite distortional hardening theories. In particular, a new hardening rule is introduced that gives very close agreement with the anisotropic experimental results in double slip yet is consistent with the axisymmetric deformation, lattice stability, and isotropic hardening that are characteristic of fcc and bcc crystals in high symmetry axial-load orientations involving 6- and 8-fold slip. DA - 2005/// PY - 2005/// DO - 10.1016/j.ijplas.2004.04.008 VL - 21 IS - 1 SP - 83-99 SN - 0749-6419 KW - crystal plasticity KW - finite deformation KW - multiple slip KW - hardening theories ER - TY - JOUR TI - Imaging temperature-dependent field emission from carbon nanotube films: Single versus multiwalled AU - Gupta, S AU - Wang, YY AU - Garguilo, JM AU - Nemanich, RJ T2 - APPLIED PHYSICS LETTERS AB - Field emission properties of vertically aligned single- and multiwalled carbon nanotube films at temperatures up to 1000°C are investigated by electron emission microscopy, enabling real-time imaging of electron emission to provide information on emission site density, the temporal variation of the emission intensity, and insight into the role of adsorbates. The nanotube films showed an emission site density of 104∼105∕cm2, which is compared to the areal density (from 1012–1013∕cm2to108–109∕cm2). At ambient temperature, the emission indicated temporal fluctuation (∼6%–8%) in emission current with minimal changes in the emission pattern. At elevated temperatures, the emission site exhibited an increase in emission site intensity. From the experimental observations, it is proposed that the chemisorbed molecules tend to desorb presumably at high applied electric fields (field-induced) in combination with thermal effects (thermal-induced) and provide a contrasting comparison between semiconducting (single-walled) and metallic (multiwalled) nanotubes. DA - 2005/2/7/ PY - 2005/2/7/ DO - 10.1063/1.1850616 VL - 86 IS - 6 SP - SN - 1077-3118 ER - TY - JOUR TI - Solid-state complexation of poly(ethylene glycol) with alpha-cyclodextrin AU - Peet, J AU - Rusa, CC AU - Hunt, MA AU - Tonelli, AE AU - Balik, CM T2 - MACROMOLECULES AB - Low-molecular-weight liquid poly(ethylene glycol) (PEG) spontaneously forms an inclusion compound (IC) when combined with α-cyclodextrin (α-CD) powder at room temperature. This process can be followed with wide-angle X-ray diffraction (WAXD). The WAXD data shows that the α-CD crystals undergo a solid-state crystal−crystal transformation from the cage to the channel crystal structure upon IC formation over a period of about 8 h. The time dependence of the 2θ = 20° α-CD channel structure X-ray peak can be described by a simple first-order kinetic model. The effects of changing the temperature, PEG:α-CD molar ratio, PEG molecular weight, and vacuum-drying the CD have been studied. The barrier opposing the PEG inclusion-induced solid-state transformation of α-CD from the cage to the channel crystal structure appears to be dominated by changes in the packing/interactions of α-CDs, rather than the loss in the conformational entropy experienced by the PEG chains during the inclusion process. DA - 2005/1/25/ PY - 2005/1/25/ DO - 10.1021/ma048103f VL - 38 IS - 2 SP - 537-541 SN - 1520-5835 ER - TY - JOUR TI - Preparation and characterization of atomically clean, stoichlometric surfaces of AIN(0001) AU - Mecouch, WJ AU - Wagner, BP AU - Reitmeier, ZJ AU - Davis, RF AU - Pandarinath, C AU - Rodriguez, BJ AU - Nemanich, RJ T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A AB - In situ exposure of the (0001) surface of AlN thin films to flowing ammonia at 1120 °C and 10−4Torr removes oxygen∕hydroxide and hydrocarbon species below the detectable limits of x-ray photoelectron spectroscopy and decreases the Al∕N ratio from 1.3 to 1.0. The positions of the Al2p and the N1s core level peaks acquired from the cleaned surfaces were 75.0±0.1eV and 398.2±0.1eV, respectively, which were similar to the values determined for the as-loaded samples. The cleaning process left unchanged the (1×1) low energy electron diffraction pattern, the step-and-terrace microstructure, and the root mean square roughness values observed for the surfaces of the as-loaded samples; i.e., the surface structure and microstructure were not changed by the high-temperature exposure to ammonia at low pressures. Vacuum annealing under 10−7Torr at 1175 °C for 15 min removed all detectable hydrocarbons; however, it did not remove the oxygen∕hydroxide species. DA - 2005/// PY - 2005/// DO - 10.1116/1.1830497 VL - 23 IS - 1 SP - 72-77 SN - 0734-2101 ER - TY - PAT TI - Methods of fabricating gallium nitride semiconductor layers on substrates including non-gallium nitride posts AU - Linthicum, K. J. AU - Gehrke, T. AU - Davis, R. F. C2 - 2005/// DA - 2005/// PY - 2005/// ER - TY - JOUR TI - Low loss tungsten-based electrode technology for microwave frequency BST varactors AU - Maria, JP AU - Boyette, BA AU - Kingon, AI AU - Ragaglia, C AU - Stauf, G T2 - JOURNAL OF ELECTROCERAMICS DA - 2005/1// PY - 2005/1// DO - 10.1007/s10832-005-6587-z VL - 14 IS - 1 SP - 75-81 SN - 1385-3449 KW - microwave KW - BST KW - electrode KW - ferroelectric KW - metallization ER - TY - JOUR TI - Effect of grain size from millimeters to nanometers on the flow stress and deformation kinetics of Ag AU - Conrad, H AU - Jung, K T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING AB - Data on the effects of grain size, d = 9 nm to 0.26 mm on the flow stress and plastic deformation kinetics of Ag at low homologous temperatures were evaluated. Two regimes were identified for this grain-size range: Regime I (d > 500 nm) and Regime II (d ≈ 10–500 nm). The effect of grain size on the flow stress in both regimes could be described by a Hall–Petch equation. KH–P was however significantly smaller and σi larger for Regime II compared to I. Dislocation activity occurred in both regimes; dislocation cells were observed in Regime I, but not reported for II. The available data suggest that the dislocation density model governs the grain-size dependence of the flow stress in Regime I and that dislocation pile-up applies in Regime II. The rate-controlling mechanism(s) in each of the two regimes are discussed. DA - 2005/1/25/ PY - 2005/1/25/ DO - 10.1016/j.msea.2004.08.073 VL - 391 IS - 1-2 SP - 272-284 SN - 0921-5093 KW - grain size KW - Hall-Petch KW - dislocations KW - grain boundary shear KW - deformation kinetics ER - TY - JOUR TI - High Q (Ba, Sr) TiO3 interdigitated capacitors fabricated on low cost polycrystalline alumina substrates with copper metallization AU - Ghosh, D. AU - Laughlin, B. J. AU - Nath, J. AU - Kingon, A. I. AU - Steer, M. B. AU - Maria, J. P. T2 - Ceramic Engineering and Science Proceedings AB - Barium Strontium Titanate (BST) ferroelectric thin films are attractive for radio frequency and microwave applications. However, for many non-military uses, the high cost of conventionally processed devices is a limiting factor. This high cost stems from the use of single-crystalline sapphire, MgO, or LaAlO3 substrates and Pt or Au metallization commonly used. Here we present a device process and materials complement offering a low cost alternative. Planar interdigitated capacitors Ba0.75Sr0.25TiO3 (BST) thin films with chromium/copper top electrodes were fabricated on polycrystalline alumina substrates using a single step photolithographic technique and lift-off. RF magnetron sputtering was used for fabrication of BST thin films while Cu thin films were thermally evaporated The dielectric tunability of the Ba0.75Sr0.25TiO3 IDCs was 40% for an applied electric field of 120 kV/cm, which corresponds to 3 μm electrode gap spacing and a 35 volt dc bias. Low frequency (1MHz) loss measurements reveal a dielectric Q ∼ 100 while a device Q of ∼30 is obtained at 26 GHz. The reduction of Q between 0.1 and 26 GHz can be attributed to the metallization. Leakage current measurements of the BST planar varactors show current densities of 1.0 × 10−6 A/cm2 for an electric field of 100 kV/cm. These dielectric characteristics (tunability and Q value) are comparable to numerous reports of IDCs with BST films prepared on expensive single crystalline substrates using noble metallization. As such, this technology is significantly less expensive, and amenable to large volume manufacturing. DA - 2005/// PY - 2005/// DO - 10.1002/9780470291252.ch13 VL - 26 IS - 5 SP - 125-132 ER - TY - JOUR TI - A tunable combline bandpass filter using Barium Strontium Titanate interdigital varactors on an alumina substrate AU - Nath, J AU - Ghosh, D AU - Fathelbab, W AU - Maria, JP AU - Kingon, AI AU - Franzon, PD AU - Steer, MB T2 - 2005 IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM, VOLS 1-4 AB - Barium strontium titanate (BST) has a field-dependent permittivity that enables it to be used as a dielectric in a voltage-tunable capacitor or varactor. A tunable combline bandpass filter was designed and characterized using BST varactors fabricated on a polycrystalline alumina substrate with copper metallization and is 14 mm /spl times/ 14 mm in size. The center frequency of the filter varies from 1.6 to 2.0 GHz with the application of 200 V tuning voltage. A 25% tuning range was achieved using tuning field strength of 300 kV/cm. The zero bias insertion loss was 6.6 dB and this decreased to 4.3 dB at the high bias state. The return loss was better than 10 dB. DA - 2005/// PY - 2005/// DO - 10.1109/mwsym.2005.1516670 SP - 595-598 SN - 2576-7216 KW - Barium Strontium Titanate (BST) KW - ferroelectric KW - microstrip filters KW - resonators KW - thin film devices KW - tunable filters KW - varactor ER - TY - JOUR TI - The formation of epitaxial hexagonal boron nitride on nickel substrates AU - Yang, PC AU - Prater, JT AU - Liu, W AU - Glass, JT AU - Davis, RF T2 - JOURNAL OF ELECTRONIC MATERIALS DA - 2005/12// PY - 2005/12// DO - 10.1007/s11664-005-0165-7 VL - 34 IS - 12 SP - 1558-1564 SN - 0361-5235 KW - boron nitride (BN) KW - epitaxial KW - precipitation ER - TY - JOUR TI - Self-consistent tight binding model adapted for hydrocarbon systems AU - Areshkin, DA AU - Shenderova, OA AU - Schall, JD AU - Brenner, DW T2 - MOLECULAR SIMULATION AB - A self-consistent environment-dependent tight binding method is presented that was developed to simulate eigenvalue spectra, electron densities and Coulomb potential distributions for hydrocarbon systems. The method builds on a non-self-consistent environment-dependent tight binding model for carbon [Tang et al., Phys. Rev. B 53, 979 (1996)] with parameters added to describe hydrocarbon bonds and to account for self-consistent charge transfer. A detailed description of the parameterization procedure is given. Case studies that examine electron emission-related properties of carbon nanotubes demonstrate the utility of the method. The results of these calculations indicate that field enhancement in the vicinity of a nanotube tip is higher for open-ended than for capped nanotubes. At the same time open-ended nanotubes exhibit a higher potential barrier in the tip region. This barrier deteriorates the coupling between conducting states in the nanotube and free electron states in vacuum, and may increase the field emission threshold. DA - 2005/7// PY - 2005/7// DO - 10.1080/08927020500044988 VL - 31 IS - 8 SP - 585-595 SN - 1029-0435 KW - fitting eigenvalue spectra KW - fitting electron densities KW - DF-TB ER - TY - JOUR TI - Phase behavior of triblock copolymers varying in molecular asymmetry AU - Hamersky, MW AU - Smith, SD AU - Gozen, AO AU - Spontak, RJ T2 - PHYSICAL REVIEW LETTERS AB - The transformation from ${A}_{1}B$ diblock copolymer to ${A}_{1}B{A}_{2}$ triblock copolymers varying in molecular asymmetry is investigated as the ${A}_{2}$ end block is progressively grown via chemical synthesis. Dynamic rheological measurements show that the order-disorder transition (ODT) temperatures of two copolymer series differing in composition and molecular weight decrease when the ${A}_{2}$ block is short relative to the ${A}_{1}$ block, and then increase as the length of the ${A}_{2}$ block is increased further. The resultant ODT minimum, predicted by mean-field theory, is attributed to mixing between long $B$ and short ${A}_{2}$ blocks. DA - 2005/10/14/ PY - 2005/10/14/ DO - 10.1103/physrevlett.95.168306 VL - 95 IS - 16 SP - SN - 0031-9007 ER - TY - JOUR TI - Metal oxide thin films deposited from metal organic precursors in supercritical CO2 solutions AU - Gougousi, T AU - Barua, D AU - Young, ED AU - Parsons, GN T2 - CHEMISTRY OF MATERIALS AB - This work demonstrates a novel method for deposition of metal oxide thin films, including Al2O3, ZrO2, MnOx, and RuOx where the metal−organic precursors and oxidizing agents are delivered in liquid and supercritical CO2. A cyclic deposition process is presented where reactants are introduced sequentially to control surface adsorption and byproduct removal steps. Reactions are studied in a hot wall reactor at pressures ranging from 1600 to 3600 psi at 80−200 °C, and X-ray photoelectron spectroscopy and infrared transmission confirmed metal oxide formation. We show that hydrogen peroxide is a viable O source for oxide deposition, whereas tert-butyl peracetate, which is a good electron acceptor, is less suited for oxygen donation. Capacitance versus voltage analysis of resulting Al2O3 films show good dielectric properties after post-deposition anneal. We believe that the good solvation properties of supercritical CO2 can aid in the delivery of precursors and in the removal of byproducts for advanced low-temperature processing of oxides and other materials of interest in electronic applications. DA - 2005/10/4/ PY - 2005/10/4/ DO - 10.1021/cm0510965 VL - 17 IS - 20 SP - 5093-5100 SN - 0897-4756 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000232326700027&KeyUID=WOS:000232326700027 ER - TY - JOUR TI - Gradient syntactic foams: Tensile strength, modulus and fractographic features AU - Kishore, Shankar R. AU - Sankaran, S. T2 - Materials Science & Engineering. A, Structural Materials: Properties, Microstructure and Processing DA - 2005/// PY - 2005/// VL - 412 IS - 02-Jan SP - 153-158 ER - TY - JOUR TI - Five-nanometer thick silicon on insulator layer AU - Elmasry, NA AU - Hunter, M AU - ElNaggar, A AU - Bedair, SM T2 - JOURNAL OF APPLIED PHYSICS AB - Silicon on insulator (SOI) has been achieved using epitaxially grown Si∕Y2O3∕Si structure. Silicon film as thin as 5nm was achieved. Pulsed laser deposition technique was used for the epitaxial deposition of both the Y2O3 and silicon. The growth conditions were adjusted to achieve two-dimensional growths of single crystal silicon films on Y2O3. No dislocations were observed in these silicon epitaxial films. This approach will allow the independent thickness control of both silicon and the oxide in the nanometer range. Si∕CeO2∕Si SOI structure was not as successful due to the formation of an amorphous oxide film at the interfaces. DA - 2005/11/15/ PY - 2005/11/15/ DO - 10.1063/1.1803625 VL - 98 IS - 10 SP - SN - 0021-8979 ER - TY - JOUR TI - Bulk nitride workshop - Preface AU - Freitas, JA AU - Sitar, Z T2 - JOURNAL OF CRYSTAL GROWTH DA - 2005/7/15/ PY - 2005/7/15/ DO - 10.1016/j.jcrysgro.2005.04.026 VL - 281 IS - 1 SP - 1-1 SN - 0022-0248 ER - TY - JOUR TI - Breakthroughs in optimization of mechanical properties of nanostructured metals and alloys AU - Koch, C. C. AU - Youssef, K. M. AU - Scattergood, R. O. AU - Murty, K. L. T2 - Advanced Engineering Materials DA - 2005/// PY - 2005/// DO - 10.1002/adern.200500094 VL - 7 IS - 9 SP - 787-794 ER - TY - JOUR TI - Permanent magnet alloys based on Sm2Co17; phase evolution in the quinary system Sm-Zr-Fe-Co-Cu AU - Stadelmaier, H. H. AU - Goll, D. AU - Kronmuller, H. T2 - Zeitschrift fur MetallkundeAmerican Journal of Physiology DA - 2005/// PY - 2005/// VL - 96 IS - 1 SP - 17-23 ER - TY - JOUR TI - Increased field-emission site density from regrown carbon nanotube films AU - Wang, YY AU - Gupta, S AU - Liang, M AU - Nemanich, RJ T2 - JOURNAL OF APPLIED PHYSICS AB - Electron field-emission properties of as-grown, etched, and regrown carbon nanotube thin films were investigated. The aligned carbon nanotube films were deposited by the microwave plasma-assisted chemical vapor deposition technique. The surface of the as-grown film contained a carbon nanotube mat of amorphous carbon and entangled nanotubes with some tubes protruding from the surface. Hydrogen plasma etching resulted in the removal of the surface layer, and regrowth on the etched surface displayed the formation of a new carbon nanotube mat. The emission site density and the current–voltage dependence of the field emission from all of the samples were analyzed. The results showed that the as-grown sample had a few strong emission spots and a relatively high emission current density (∼20μA∕cm2 at 1V∕μm), while the regrown sample exhibited a significantly increased emission site density. DA - 2005/5/15/ PY - 2005/5/15/ DO - 10.1063/1.1897836 VL - 97 IS - 10 SP - SN - 1089-7550 ER - TY - BOOK TI - Image analysis of food microstructure AU - Russ, J. C. CN - TX543 .R88 2005 DA - 2005/// PY - 2005/// PB - Boca Raton, LA: CRC Press SN - 0849322413 ER - TY - JOUR TI - Epitaxial growth and properties of MoOx(2