TY - JOUR TI - Oxide-oxide interfaces:: Atomistic and density functional study of cubic-ZrO2(100)||NiO(111) AU - Guo, CX AU - Warschkow, O AU - Ellis, DE AU - Dravid, VP AU - Dickey, EC T2 - Journal of The American Ceramic Society AB - The cubic‐ZrO 2 (100) ‖ NiO (111) interface provides an opportunity for comparison between atomic‐scale measurements, atomistic simulations, and theoretical electronic structures. High‐resolution electron microscopy indicates that the oxides share a common oxygen layer and that the small lattice strain is largely taken up by NiO near the interface. Using simple Coulomb plus Buckingham‐type interatomic potentials, we are able to provide a more focused picture, revealing two types of boundary. The lowest energy interface is highly planar, almost ideal in structure; there is a second interface, of higher energy, that shows a rumpled structure with strain taken up by deformation of nickel chains. Depth profiling of atomic site energies permits calculation of interface versus bulk and surface energies, and it shows that the interface effects penetrate only two to three atomic layers. Embedded cluster density functional studies of bulk and interface‐region sites permit the characterization of perturbations of electronic density around the boundaries. DA - 2001/// PY - 2001/// DO - 10.1111/j.1151-2916.2001.tb01070.x VL - 84 IS - 11 SP - 2677-2684 UR - https://app.dimensions.ai/details/publication/pub.1038119010 ER - TY - CONF TI - Metal-oxide films with magnetically-modulated nanoporous architectures AU - Grimes, CA AU - Singh, RS AU - Dickey, EC AU - Varghese, OK AB - A magnetically-driven method for controlling nano- dimensional porosity in sol gel derived metal oxide films, including TiO2, Al2O3, and SnO2, coated onto ferromagnetic amorphous substrates, such as the magnetically-soft Metglas alloys, is described. Based on the porous structures observed dependence on external magnetic field, a model is suggested to explain the phenomena. Under well-defined conditions it appears that the sol particles coming out of solution, and undergoing Brownian motion, follow the magnetic field lines oriented perpendicularly to the substrate surface associated with the magnetic domain walls of the substrate; hence the porosity developed during solvent evaporation correlates with the magnetic domain size. C2 - 2001/// C3 - Proceedings of SPIE DA - 2001/// DO - 10.1117/12.452555 VL - 4468 SP - 8-16 UR - https://app.dimensions.ai/details/publication/pub.1048154383 KW - nanodimensional KW - nanoporous KW - fabrication KW - sensor KW - biotemplating KW - metal-oxide KW - sol gel ER - TY - JOUR TI - Atomic scale analysis of cubic zirconia grain boundaries AU - Dickey, EC AU - Fan, X AU - Yong, M AU - Sinnott, SB AU - Pennycook, SJ T2 - MRS Online Proceedings Library DA - 2001/// PY - 2001/// VL - 589 SP - 323-328 ER - TY - CONF TI - A novel low temperature synthesis method for semiconductor nanowires AU - Sharma, S AU - Sunkara, MK AU - Miranda, R AU - Lian, G AU - Dickey, EC C2 - 2001/1/1/ C3 - MRS Online Proceedings Library DA - 2001/1/1/ DO - 10.1557/proc-676-y1.6 VL - 676 ER - TY - CONF TI - Measurement of modulus changes of a phenolic adhesive using nanoindentation for an inkjet printhead nozzle plate AU - Mrvos, JM AU - Patil, GS AU - Dickey, EC AU - Wonderly, CT C2 - 2001/// C3 - International Conference on Digital Printing Technologies DA - 2001/// SP - 385-391 ER - TY - CONF TI - Viral-like self assembly, from design and synthesis to microscopy. AU - Cammers-Goodwin, A AU - Zhao, B AU - Chowdhury, C AU - Dickey, EC C2 - 2001/// C3 - ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY DA - 2001/// VL - 221 SP - U111-U111 ER - TY - CONF TI - Interfacial compatibility stresses in alumina-zirconia and alumina-YAG composites AU - Frazer, CS AU - Jones, CE AU - Dickey, EC C2 - 2001/// C3 - Ceramic Transactions DA - 2001/// VL - 124 SP - 339-350 ER - TY - JOUR TI - Neutron transmutation of 10B isotope-doped diamond AU - Jagannadham, K. AU - Verghese, K. AU - Butler, J.E. T2 - Applied Physics Letters AB - Diamond samples grown by microwave plasma chemical vapor deposition and doped with 10B have been irradiated under thermal neutron flux of 1013 cm−2 s−1 for 76 h to examine transmutation of 10B to 7Li and the attendant lattice damage to diamond. To prevent graphitization and formation of diamond-like carbon, continuous cooling in water is provided during irradiation. Characterization of the diamond samples using Raman spectroscopy, photoluminescence spectroscopy, and secondary ion mass spectrometry showed that diamond remained crystalline without a major damage. Formation of vacancies due to neutron irradiation is inferred from photoluminescence spectroscopy. DA - 2001/// PY - 2001/// DO - 10.1063/1.1342207 VL - 78 IS - 4 SP - 446-447 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-0042331197&partnerID=MN8TOARS ER - TY - JOUR TI - The role of the photochemical fragmentation in laser ablation: a molecular dynamics study AU - Yingling, Yaroslava G. AU - Zhigilei, Leonid V. AU - Garrison, Barbara J. T2 - Journal of Photochemistry and Photobiology A: Chemistry AB - Despite numerous studies, the mechanistic understanding of the role of the photochemical processes and their coupling with the thermal processes in UV laser ablation is still far from being complete. In this work, the effects of the photochemical reactions on the laser ablation mechanism are delineated based on the results of molecular dynamics simulations of 248 nm laser irradiation of solid chlorobenzene. Photochemical reactions are found to release additional energy into the irradiated sample and decrease the average cohesive energy, therefore decreasing the value of the ablation threshold. The yield of emitted fragments becomes significant only above the ablation threshold. Below the ablation threshold only the most volatile photoproduct, HCl, is ejected in very small amounts, whereas the remainder of photoproducts are trapped inside the sample. Results of the simulations are in a good qualitative agreement with experimental data on the ejection of photoproducts in the laser ablation of chlorobenzene. DA - 2001/12// PY - 2001/12// DO - 10.1016/s1010-6030(01)00580-9 VL - 145 IS - 3 SP - 173-181 J2 - Journal of Photochemistry and Photobiology A: Chemistry LA - en OP - SN - 1010-6030 UR - http://dx.doi.org/10.1016/s1010-6030(01)00580-9 DB - Crossref KW - photochemical fragmentation KW - laser ablation KW - molecular dynamics ER - TY - JOUR TI - Photochemical fragmentation processes in laser ablation of organic solids AU - Yingling, Yaroslava G. AU - Zhigilei, Leonid V. AU - Garrison, Barbara J. T2 - Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms AB - Studies on ultraviolet (UV) laser ablation of molecular solids have received considerable attention due to its proven and potential applications. Despite its active practical use the mechanisms of laser ablation are still being studied and debated. One crucial mechanistic discussion is on the relative importance of direct photodissociation of chemical bonds versus thermal ejection following rapid conversion of light energy into heat in the ablation processes. It is generally believed that these two processes are coupled in UV ablation resulting in difficulty in analyzing the relative importance of the two mechanisms. In the simulations presented here the breathing sphere model is enhanced allowing the photon absorption event to break a bond in the molecule and then have subsequent abstraction and recombination reactions. The initial system to model is chlorobenzene. Chlorobenzene is chosen because of simplicity of its fragmentation, entailing exclusively scission of the carbon–chlorine bond to yield phenyl and chlorine radicals. The results from the simulations allow us to study the photochemical events and their coupling with the thermal processes. DA - 2001/6// PY - 2001/6// DO - 10.1016/s0168-583x(01)00414-1 VL - 180 IS - 1-4 SP - 171-175 J2 - Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms LA - en OP - SN - 0168-583X UR - http://dx.doi.org/10.1016/s0168-583x(01)00414-1 DB - Crossref KW - molecular dynamics simulations KW - laser ablation KW - photofragmentation ER - TY - JOUR TI - Laser ablation of bicomponent systems: A probe of molecular ejection mechanisms AU - Yingling, Yaroslava G. AU - Zhigilei, Leonid V. AU - Garrison, Barbara J. AU - Koubenakis, Antonis AU - Labrakis, John AU - Georgiou, Savas T2 - Applied Physics Letters AB - A combined experimental and molecular dynamics simulation study of laser ablation of a model bicomponent system with solutes of different volatility provides a consistent picture of the mechanisms of material ejection. The comparison of the ejection yields shows that there are two distinct regimes of molecular ejection, desorption at low laser fluences, and a collective ejection of a volume of material or ablation at higher fluences. Ejection of volatile solutes dominates in the desorption regime, whereas nonvolatile solutes are ejected only in the ablation regime. DA - 2001/3/12/ PY - 2001/3/12/ DO - 10.1063/1.1353816 VL - 78 IS - 11 SP - 1631-1633 J2 - Appl. Phys. Lett. LA - en OP - SN - 0003-6951 1077-3118 UR - http://dx.doi.org/10.1063/1.1353816 DB - Crossref ER - TY - JOUR TI - Structure and phase characteristics of amorphous boron-carbon-nitrogen under high pressure and high temperature AU - HUANG, JY AU - ZHU, YT AU - MORI, H T2 - JOURNAL OF MATERIALS RESEARCH DA - 2001/// PY - 2001/// VL - 16 IS - 4 SP - 1178-1184 ER - TY - JOUR TI - On the influence of fiber shape in bone-shaped short-fiber composites AU - BEYERLEIN, IJ AU - ZHU, YT AU - MAHESH, S T2 - COMPOSITES SCIENCE AND TECHNOLOGY DA - 2001/// PY - 2001/// VL - 61 IS - 10 SP - 1341-1357 ER - TY - JOUR TI - Microstructures and properties of ultrafine-grained pure titanium processed by equal-channel angular pressing and cold deformation AU - STOLYAROV, , VV AU - ZHU, YT AU - LOWE, TC AU - al., T2 - JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY DA - 2001/// PY - 2001/// VL - 1 IS - 2 SP - 237-242 ER - TY - JOUR TI - Microstructures and dislocation configurations in nanostructured Cu processed by repetitive corrugation and straightening AU - HUANG, JY AU - ZHU, YT AU - JIANG, H AU - al., T2 - ACTA MATERIALIA DA - 2001/// PY - 2001/// VL - 49 IS - 9 SP - 1497-1505 ER - TY - JOUR TI - Microstructure and properties of pure Ti processed by ECAP and cold extrusion AU - STOLYAROV, , VV AU - ZHU, YT AU - LOWE, TC AU - al., T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING DA - 2001/// PY - 2001/// VL - 303 IS - 1-2 SP - 82-89 ER - TY - JOUR TI - Influence of ECAP routes on the microstructure and properties of pure Ti AU - STOLYAROV, , VV AU - ZHU, YT AU - ALEXANDROV, , IV AU - al., T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING DA - 2001/// PY - 2001/// VL - 299 IS - 1-2 SP - 59-67 ER - TY - JOUR TI - Fracture toughness of a composite reinforced with bone-shaped short fibers AU - ZHU, YT AU - BEYERLEIN, IJ AU - VALDEZ, JA AU - al., T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING DA - 2001/// PY - 2001/// VL - 317 IS - 1-2 SP - 93-100 ER - TY - JOUR TI - Effect of lattice strain and defects on the superconductivity of MgB2 AU - SERQUIS, A AU - ZHU, YT AU - PETERSON, EJ AU - al., T2 - APPLIED PHYSICS LETTERS DA - 2001/// PY - 2001/// VL - 79 IS - 26 SP - 4399-4401 ER - TY - JOUR TI - Deformation behavior and plastic instabilities of ultrafine-grained titanium AU - JIA, D AU - WANG, YM AU - RAMESH, KT AU - al., T2 - APPLIED PHYSICS LETTERS DA - 2001/// PY - 2001/// VL - 79 IS - 5 SP - 611-613 ER - TY - JOUR TI - A new route to bulk nanostructured metals AU - ZHU, YT AU - JIANG, HG AU - HUANG, JY AU - al., T2 - METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE DA - 2001/// PY - 2001/// VL - 32 IS - 6 SP - 1559-1562 ER - TY - JOUR TI - Visible photoluminescence from ruthenium-doped multiwall carbon nanotubes AU - Dickey, EC AU - Grimes, CA AU - Jain, MK AU - Ong, KG AU - Qian, D AU - Kichambare, PD AU - Andrews, R AU - Jacques, D T2 - Applied Physics Letters AB - Visible photoluminescence at 515 nm of ruthenium-doped multiwall carbon nanotubes, fabricated on quartz substrates using a chemical vapor deposition technique, is reported. The well-aligned nanotubes serve as templates for the luminescent, residual ruthenium–iron catalyst particles contained within the nanotubes, restricting the particle size to about 10 nm. The synthesis technique can be readily extended to other luminescent dopants; moreover, since nanotube arrays can be readily grown from patterned substrates, nanotube-based optoelectronic devices may be achieved. DA - 2001/// PY - 2001/// DO - 10.1063/1.1419238 VL - 79 IS - 24 SP - 4022-4024 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000172489100039&KeyUID=WOS:000172489100039 ER - TY - JOUR TI - Viral-like self assembly, from design and synthesis to microscopy. AU - Cammers-Goodwin, A AU - Zhao, B AU - Chowdhury, C AU - Dickey, EC T2 - Abstracts of Papers of the American Chemical Society DA - 2001/// PY - 2001/// VL - 221 SP - U111 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000168824800657&KeyUID=WOS:000168824800657 ER - TY - JOUR TI - Titanium oxide nanotube arrays prepared by anodic oxidation AU - Gong, D AU - Grimes, CA AU - Varghese, OK AU - Hu, WC AU - Singh, RS AU - Chen, Z AU - Dickey, EC T2 - Journal of Materials Research DA - 2001/// PY - 2001/// DO - 10.1557/JMR.2001.0457 VL - 16 IS - 12 SP - 3331-3334 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000172585100001&KeyUID=WOS:000172585100001 ER - TY - JOUR TI - Structure and chemistry of yttria-stabilized cubic-zirconia symmetric tilt grain boundaries AU - Dickey, EC AU - Fan, XD AU - Pennycook, SJ T2 - Journal of The American Ceramic Society AB - The atomic structures of two symmetric [001] tilt grain boundaries in yttria‐stabilized cubic‐zirconia, Σ5 (310) and near‐Σ13 (510), are studied by Z ‐contrast scanning transmission electron microscopy. Both boundaries are composed of periodic arrays of highly symmetric structural units, with a distinct unit for each boundary. Oxygen K ‐edge electron energy‐loss spectra show that the oxygen coordination is similar between the bulk and grain boundary, indicating that oxygen ions within the grain boundary reside in distorted tetrahedral sites. Atomic models of the grain boundaries are proposed that are consistent with the experimental data. The core structures are different from previously studied metal or oxide grain boundaries and are unique to the fluorite structure. Yttrium segregation to the grain boundaries is also investigated by electron energy‐loss spectroscopy. Yttrium is found to segregate preferentially to the Σ5 grain boundary, and the spatial distribution of the segregation layer is confined to within 1 nm of the boundary plane. DA - 2001/// PY - 2001/// DO - 10.1111/j.1151-2916.2001.tb00842.x VL - 84 IS - 6 SP - 1361-1368 UR - https://app.dimensions.ai/details/publication/pub.1025892814 ER - TY - JOUR TI - Purification and structural annealing of multiwalled carbon nanotubes at graphitization temperatures AU - Andrews, R AU - Jacques, D AU - Qian, D AU - Dickey, EC T2 - Carbon AB - In this work, we present a systematic study of the effects of graphitization on the structural perfection of multiwalled carbon nanotubes. High purity nanotubes were produced by a low temperature CVD method and subsequently annealed at temperatures between 1600 and 3000°C. The nanotubes were characterized for chemical purity, interlayer spacing, and defect healing. The graphitization procedure was found to remove residual metal catalyst in the nanotubes and reduce the wall defects as reflected in a reduced interlayer spacing between the graphene shells. Graphitization presents a low-cost, commercially viable method of purifying and ordering multiwall carbon nanotubes. DA - 2001/// PY - 2001/// DO - 10.1016/S0008-6223(00)00301-8 VL - 39 IS - 11 SP - 1681-1687 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000170525000008&KeyUID=WOS:000170525000008 ER - TY - JOUR TI - Preferred crystallographic orientation relationships of nickel films deposited on (100) cubic-zirconia substrates (vol 372, pg 37, 2000) AU - Dickey, EC AU - Ma, Y AU - Bagiyono AU - Lian, GD AU - Sinnott, SB AU - Wagner, T T2 - Thin Solid Films DA - 2001/// PY - 2001/// DO - 10.1016/S0040-6090(01)00801-X VL - 384 IS - 2 SP - 307 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000167437800026&KeyUID=WOS:000167437800026 ER - TY - JOUR TI - Oxide-oxide interfaces: Atomistic and density functional study of cubic-ZrO2(100)vertical bar vertical bar NiO(111) AU - Guo, CX AU - Warschkow, O AU - Ellis, DE AU - Dravid, VP AU - Dickey, EC T2 - Journal of the American Ceramic Society DA - 2001/// PY - 2001/// VL - 84 IS - 11 SP - 2677-2684 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000172137000035&KeyUID=WOS:000172137000035 ER - TY - JOUR TI - Metal-oxide films with magnetically-modulated nanoporous architectures AU - Grimes, CA AU - Singh, RS AU - Dickey, EC AU - Varghese, OK T2 - Journal of Materials Research DA - 2001/// PY - 2001/// DO - 10.1557/JMR.2001.0234 VL - 16 IS - 6 SP - 1686-1693 UR - https://app.dimensions.ai/details/publication/pub.1027854055 ER - TY - BOOK TI - Measurement of modulus changes of a phenolic adhesive using nanoindentation for an inkjet printhead nozzle plate AU - Mrvos, JM AU - Patil, GS AU - Dickey, EC AU - Wonderly, CT DA - 2001/// PY - 2001/// PB - SE - 385-391 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000183952700086&KeyUID=WOS:000183952700086 ER - TY - CHAP TI - Interfacial compatibility stresses in alumina-zirconia and alumina-YAG composites AU - Frazer, CS AU - Jones, CE AU - Dickey, EC T2 - Advances in Ceramic Matrix Composites Vi PY - 2001/// VL - 124 SP - 339-350 PB - SE - UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000171046100029&KeyUID=WOS:000171046100029 ER - TY - JOUR TI - In-situ transmission electron microscopy studies of polymer-carbon nanotube composite deformation AU - Qian, D AU - Dickey, EC T2 - Journal of Microscopy-Oxford AB - This paper demonstrates the viability of in-situ transmission electron microscopy for studying the deformation mechanisms of polymer nano-composites. In-situ straining studies are performed on carbon multiwalled nanotube (MWNT)-polystyrene composite films. The experiments show that load transfer across the nanotube-polystyrene interface is operative well into the plastic deformation regime of the composite film. The MWNTs are observed to bridge cracks propagating through the polystyrene, providing closure stresses across the crack wake. Although some MWNTs fracture by either a sword-in-sheath mechanism or transverse shear fracture, most of the MWNTs eventually debond at the MWNT-polymer interface and subsequently pull out of the matrix. DA - 2001/// PY - 2001/// DO - 10.1046/j.1365-2818.2001.00940.x VL - 204 SP - 39-45 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000171285700005&KeyUID=WOS:000171285700005 KW - carbon nanotube KW - in-situ transmission electron microscopy KW - polymer composite ER - TY - JOUR TI - Gas sensing characteristics of multi-wall carbon nanotubes AU - Varghese, OK AU - Kichambre, PD AU - Gong, D AU - Ong, KG AU - Dickey, EC AU - Grimes, CA T2 - Sensors and Actuators B-Chemical AB - Impedance spectroscopy was used to study the gas sensing behavior of both capacitance and resistance based sensors employing multi-wall carbon nanotubes (MWNTs) as the active sensing element. Studies revealed the chemisorption of reducing gases upon the surface of the MWNTs. Increasing sensor impedance was observed with increasing humidity or partial pressures of ammonia, carbon monoxide, and carbon dioxide. The impedance changes are attributed to p-type conductivity in semiconducting MWNTs, and the formation of Schottky barriers between the metallic and semiconducting nanotubes. Reversible behavior is demonstrated for the MWNT sensors in response to humidity, carbon monoxide and carbon dioxide. The MWNT sensors strongly respond to ammonia behaving as dosimeters. DA - 2001/// PY - 2001/// DO - 10.1016/S0925-4005(01)00923-6 VL - 81 IS - 1 SP - 32-41 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000172710900005&KeyUID=WOS:000172710900005 KW - carbon nanotubes KW - gas sensor KW - impedance ER - TY - JOUR TI - Effect of purification of the electrical conductivity and complex permittivity of multiwall carbon nanotubes AU - Grimes, CA AU - Dickey, EC AU - Mungle, C AU - Ong, KG AU - Qian, D T2 - Journal of Applied Physics AB - In this work we report on the complex permittivity spectra and electrical conductivity of both as-fabricated and graphitized multiwall carbon nanotubes (MWNTs). The high-temperature annealing removes the Fe3C catalyst particles present in the as-fabricated material, enabling the intrinsic MWNT properties to be measured. The permittivity spectra of 1 wt % MWNT-polystyrene composite films are measured from 75 to 1875 MHz. Comparison of measurements with an appropriate effective medium model shows that the residual catalyst inclusions in the core of the nanotube increase the average electrical conductivity by approximately a factor of 3.5. DA - 2001/// PY - 2001/// DO - 10.1063/1.1400100 VL - 90 IS - 8 SP - 4134-4137 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000171562100067&KeyUID=WOS:000171562100067 ER - TY - JOUR TI - Crystallographic texture and orientation variants in Al2O3-Y3Al5O12 directionally solidified eutectic crystals AU - Frazer, CS AU - Dickey, EC AU - Sayir, A T2 - Journal of Crystal Growth AB - Eutectic rods of Al2O3 and Y3Al5O12 were grown by a laser-heated float zone method, and their microstructure and crystallographic texture were studied by scanning electron microscopy, electron-backscattered diffraction and X-ray diffraction. The composites were found to be highly textured with two twin-related crystallographic orientation relationships between the phases. Electron-backscattered diffraction was employed to determine the spatial distribution of the orientational variants within the samples and to define the crystallographic orientation of various microstructural features. DA - 2001/// PY - 2001/// DO - 10.1016/S0022-0248(01)01590-1 VL - 233 IS - 1-2 SP - 187-195 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000170986400026&KeyUID=WOS:000170986400026 KW - characterization KW - directional solidification KW - eutectics KW - interfaces KW - floating zone technique KW - oxides ER - TY - JOUR TI - Bulk synthesis of silicon nanowires using a low-temperature vapor-liquid-solid method AU - Sunkara, MK AU - Sharma, S AU - Miranda, R AU - Lian, G AU - Dickey, EC T2 - Applied Physics Letters AB - Silicon nanowires will find applications in nanoscale electronics and optoelectronics both as active and passive components. Here, we demonstrate a low-temperature vapor–liquid–solid synthesis method that uses liquid-metal solvents with low solubility for silicon and other elemental semiconductor materials. This method eliminates the usual requirement of quantum-sized droplets in order to obtain quantum-scale one-dimensional structures. Specifically, we synthesized silicon nanowires with uniform diameters distributed around 6 nm using gallium as the molten solvent, at temperatures less than 400 °C in hydrogen plasma. The potential exists for bulk synthesis of silicon nanowires at temperatures significantly lower than 400 °C. Gallium forms a eutectic with silicon near room temperature and offers a wide temperature range for bulk synthesis of nanowires. These properties are important for creating monodispersed one-dimensional structures capable of yielding sharp hetero- or homointerfaces. DA - 2001/// PY - 2001/// DO - 10.1063/1.1401089 VL - 79 IS - 10 SP - 1546-1548 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000170647200046&KeyUID=WOS:000170647200046 ER - TY - CHAP TI - Atomic scale analysis of cubic zirconia grain boundaries AU - Dickey, EC AU - Fan, X AU - Yong, M AU - Sinnott, SB AU - Pennycook, SJ T2 - Advances in Materials Problem Solving With the Electron Microscope PY - 2001/// VL - 589 SP - 323-328 PB - SE - UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000172649100048&KeyUID=WOS:000172649100048 ER - TY - JOUR TI - Self-assembled epitaxial and polycrystalline magnetic nickel nanocrystallites AU - Kumar, Dhananjay AU - Zhou, H. AU - Nath, T.K. AU - Kvit, Alex V. AU - Narayan, J. T2 - Applied Physics Letters AB - Nanocrystalline nickel particles were embedded in amorphous alumina and crystalline TiN matrices using a pulsed-laser deposition process to investigate the effect of texturing on magnetic properties of nickel nanocrystallites. The crystalline quality of both the matrix and magnetic particles were investigated by cross-sectional high-resolution transmission electron microscopy. The embedded Ni nanocrystals were found to be epitaxial in case of TiN matrix and polycrystalline in Al2O3 amorphous matrix. The Ni nanocrystals on TiN/Si grow epitaxially because the TiN acting as a template grows epitaxially on Si substrate via domain epitaxy. On the other hand, Ni nanocrystals in Al2O3 matrix are polycrystalline because of the amorphous nature of the alumina matrix. Magnetization versus temperature measurements have shown that the blocking temperature, above which the samples lose magnetization-field (M–H) hysteretic behavior, of Ni–TiN sample (∼190 K) is significantly higher than that of Ni–Al2O3 sample (∼30 K) with a similar size distribution of embedded magnetic particles. A comparison of the values of coercivity (Hc) of the two samples, measured from M–H data, indicates that epitaxial Ni nanocrystals also exhibit significantly higher coercivity than polycrystalline Ni particles. The high values of TB and Hc of Ni–TiN samples with respect to TB of Ni–Al2O3 samples are believed to be associated with preferred alignment of nanocrystallites. DA - 2001/10/22/ PY - 2001/10/22/ DO - 10.1063/1.1412428 VL - 79 IS - 17 SP - 2817-2819 ER - TY - JOUR TI - Low temperature synthesis and electrical properties of epitaxial Sr0.8Bi2.2Ta2O9 thin films AU - Chattopadhyay, Soma AU - Kvit, A. AU - Kumar, Dhananjay AU - Sharma, A.K. AU - Sankar, Jagannathan AU - Narayan, Jagdish AU - Knight, V.S. AU - Coleman, T.S. AU - Lee, Clinton B. T2 - Applied Physics Letters AB - High quality epitaxial thin films of Sr0.8Bi2.2Ta2O9 (SBT) were grown on LaNiO3 (LNO) bottom electrodes. The SBT/LNO heterostructure was fabricated on (001) oriented LaAlO3 substrates by pulsed laser ablation. X-ray diffraction and high resolution transmission electron microscopy revealed epitaxial growth of SBT and LNO layers along the (001) direction and sharp interfaces between the epilayers. The SBT films exhibited a dielectric constant of ∼270 and the loss tangent varied from 0.02 to 0.04. The dielectric constant measured as a function of bias field revealed that the films were not ferroelectric in nature. The room temperature frequency response of the dielectric constant was observed to obey Curie–von Schweidler power law with an exponent of 0.02 in the range of 10 kHz–1 MHz. DA - 2001/5/28/ PY - 2001/5/28/ DO - 10.1063/1.1374226 VL - 78 IS - 22 SP - 3514-3516 ER - TY - JOUR TI - Structure of human DNMT2, an enigmatic DNA methyltransferase homolog that displays denaturant-resistant binding to DNA AU - Dong, AP AU - Yoder, JA AU - Zhang, X AU - Zhou, L AU - Bestor, TH AU - Cheng, XD T2 - NUCLEIC ACIDS RESEARCH AB - DNMT2 is a human protein that displays strong sequence similarities to DNA (cytosine-5)-methyltransferases (m(5)C MTases) of both prokaryotes and eukaryotes. DNMT2 contains all 10 sequence motifs that are conserved among m(5)C MTases, including the consensus S:-adenosyl-L-methionine-binding motifs and the active site ProCys dipeptide. DNMT2 has close homologs in plants, insects and Schizosaccharomyces pombe, but no related sequence can be found in the genomes of Saccharomyces cerevisiae or Caenorhabditis elegans. The crystal structure of a deletion mutant of DNMT2 complexed with S-adenosyl-L-homocysteine (AdoHcy) has been determined at 1.8 A resolution. The structure of the large domain that contains the sequence motifs involved in catalysis is remarkably similar to that of M.HHAI, a confirmed bacterial m(5)C MTase, and the smaller target recognition domains of DNMT2 and M.HHAI are also closely related in overall structure. The small domain of DNMT2 contains three short helices that are not present in M.HHAI. DNMT2 binds AdoHcy in the same conformation as confirmed m(5)C MTases and, while DNMT2 shares all sequence and structural features with m(5)C MTases, it has failed to demonstrate detectable transmethylase activity. We show here that homologs of DNMT2, which are present in some organisms that are not known to methylate their genomes, contain a specific target-recognizing sequence motif including an invariant CysPheThr tripeptide. DNMT2 binds DNA to form a denaturant-resistant complex in vitro. While the biological function of DNMT2 is not yet known, the strong binding to DNA suggests that DNMT2 may mark specific sequences in the genome by binding to DNA through the specific target-recognizing motif. DA - 2001/1/15/ PY - 2001/1/15/ DO - 10.1093/nar/29.2.439 VL - 29 IS - 2 SP - 439-448 SN - 0305-1048 ER - TY - CHAP TI - Interleukin-13 induced mucous cell hyperplasia in airway epithelium. AU - Martin, L. D. AU - Macchione, M. AU - Bonner, J. C. AU - Booth, B. W. AU - Akley, N. J. AU - Adler, K. B. T2 - Cilia and mucus: from development to respiratory disease. PY - 2001/// SP - 253-263 ER - TY - JOUR TI - Differentiation of murine tracheal epithelial cells in vitro. AU - Macchione, M. AU - Akley, N. J. AU - Adler, K. B. AU - Martin, L. D. T2 - American Journal of Respiratory and Critical Care Medicine DA - 2001/// PY - 2001/// VL - 163 SP - A225 ER - TY - PAT TI - Thin film optical measurement system and method with calibrating ellipsometer AU - Aspnes, D. E. AU - Opsal, J. AU - Faton, J. T. C2 - 2001/// DA - 2001/// PY - 2001/// ER - TY - PAT TI - Ellipsometer and polarimeter with zero-order plate compensator AU - Aspnes, D. E. AU - Law, J. Y. C2 - 2001/// DA - 2001/// PY - 2001/// ER - TY - PAT TI - Broadband spectroscopic rotating compensator ellipsometer AU - Aspnes, D. E. AU - Opsal, J. C2 - 2001/// DA - 2001/// PY - 2001/// ER - TY - PAT TI - Method of forming haze-free BST films AU - Basceri, C. AU - Sandhu, G. C2 - 2001/// DA - 2001/// PY - 2001/// ER - TY - PAT TI - Method for improving the sidewall stoichiometry of thin film capacitors AU - Basceri, C. C2 - 2001/// DA - 2001/// PY - 2001/// ER - TY - PAT TI - Method for improving the resistance degradation of thin film capacitors AU - Basceri, C. AU - Al-Shareef, H. N. C2 - 2001/// DA - 2001/// PY - 2001/// ER - TY - PAT TI - Dielectric cure for reducing oxygen vacancies AU - Basceri, C. AU - Sandhu, G. S. C2 - 2001/// DA - 2001/// PY - 2001/// ER - TY - CONF TI - Supporting lab report writing in an introductory materials engineering lab AU - Wiebe, E. N. AU - Hare, T. M. AU - Carter, M. AU - Fahmy, Y. AU - Russell, R. AU - Ferzli, M. C2 - 2001/// C3 - 2001 ASEE annual conference & exposition: Proceedings ; June 24-27, 2001, Albuquerque Convention Center, Albuquerque, New Mexico DA - 2001/// PB - Washington, DC: ASEE ER - TY - JOUR TI - Linear and nonlinear optical spectroscopy of surfaces and interfaces AU - Aspnes, DE T2 - PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE AB - I review some of the basic physics that determines the optical properties of surfaces and interfaces, proceeding from the optical properties of bulk material through photon-driven localization to microscopic formulations at the bond level. Bond models may provide more insight than band models for interpreting processes that take place within a monolayer or so of the interface, as for example second-harmonic generation in crystals with inversion symmetry. DA - 2001/12/16/ PY - 2001/12/16/ DO - 10.1002/1521-396x(200112)188:4<1353::aid-pssa1353>3.0.co;2-m VL - 188 IS - 4 SP - 1353-1360 SN - 1862-6319 ER - TY - BOOK TI - Forensic uses of digital imaging AU - Russ, J. C. AB - It happens all too often: The vague images of a poor quality video from a surveillance camera splash across the screen in a darkened courtroom and the guilt or innocence of the defendant hinges on whether or not the jury can determine if he or she is really the person in those images. Interpretation and misinterpretation of information about imagin CN - TA219 .R87 2001 DA - 2001/// PY - 2001/// DO - 10.1201/9781420041477 PB - Boca Raton: CRC Press SN - 0849309034 ER - TY - JOUR TI - Thick electrodes for high frequency high Q tunable ferroelectric thin film varactors AU - Stauf, G. T. AU - Ragaglia, C. AU - Roeder, J. F. AU - Vestyck, D. AU - Maria, J. P. AU - Ayguavives, T. AU - Kingon, A. AU - Mortazawi, A. AU - Tombak, A. T2 - Integrated Ferroelectrics AB - Abstract Thin film barium strontium titanate (BST) shows great promise for voltage tunable dielectric devices for use at RF and microwave frequencies. An MOCVD process has been developed for production of BST, resulting in films with very low losses (as low as 0.002–0.004) and tunabilities over 50% at low operation voltages. With these values of BST loss, overall device quality factors at RF (100 MHz+) frequencies are primarily limited by losses in the thin metal electrodes, such as Pt, normally used for ferroelectric thin films. The bottom electrode in parallel plate capacitor structures is particularly challenging, since it must provide a good growth surface for BST and be stable at high (>600 °C) growth temperatures in an oxidizing atmosphere yet have high conductivity and compatibility with Si or SiO2/Si substrates. These challenges have previously prevented use of Pt thicknesses over 0.1–0.2 urn. Our solution to this problem, involves combinations of adhesion layers at the Pt/SiO2 interface and embedded stabilization layers to make functioning Pt bottom electrodes as thick as 2 μm. Devices with dielectric Q factors over 150 at 100 MHz (tan δ ∼ 0.006 as measured and modeled by S-parameters) and overall device Q factors over 50 at 30 MHz are described. We have also inserted these devices into tunable filters, achieving tunabilities of 50% and low insertion losses (0.3 dB) at RF frequencies. DA - 2001/// PY - 2001/// DO - 10.1080/10584580108011955 VL - 39 IS - 1-4 SP - 1271-1280 ER - TY - JOUR TI - The low-voltage-switching behavior of sol-gel-derived Pb(Zr,Ti)O-3 thin film capacitors AU - Kim, S. H. AU - Park, D. Y. AU - Woo, H. J. AU - Lee, D. S. AU - Ha, J. W. AU - Hwang, C. S. AU - Jeong, S. AU - Kingon, A. I. T2 - Integrated Ferroelectrics DA - 2001/// PY - 2001/// VL - 39 IS - 1-4 SP - 963-972 ER - TY - CONF TI - Instructional software: if you build It, they may or may not come AU - Roskowski, A. M. AU - Felder, R.M. AU - Bullard, L. G. C2 - 2001/// C3 - 2001 ASEE Annual Conference Proceedings, ASEE, June 2001 CN - T62. A47 2001 DA - 2001/// PB - Washington, D.C.: American Society for Engineering Education ER - TY - JOUR TI - Contribution of dielectric and metallic losses in RF/microwave tunable varactors using (Ba,Sr)TiO3 thin films AU - Ayguavives, F. AU - Jin, Z. AU - Tombak, A. AU - Maria, J. P. AU - Mortazawi, A. AU - Kingon, A. I. T2 - Integrated Ferroelectrics DA - 2001/// PY - 2001/// VL - 39 IS - 1-4 SP - 1343-1352 ER - TY - JOUR TI - Study of TaSiN diffusion barrier AU - Letendu, F. AU - Hugon, M. C. AU - Agius, B. AU - Aubert, P. AU - Coindeau, S. AU - Kingon, A. I. T2 - Integrated Ferroelectrics DA - 2001/// PY - 2001/// VL - 38 IS - 1-4 SP - 865-872 ER - TY - JOUR TI - Spread coating of OPA on mica: From multilayers to self-assembled monolayers AU - Neves, BRA AU - Salmon, ME AU - Russell, PE AU - Troughton, EB T2 - LANGMUIR AB - The process of self-assembled monolayer (SAM) formation by the spread coating of an octadecylphosphonic acid (OPA) solution onto a mica surface is investigated by atomic force microscopy. When concentrated solutions are employed, a novel mechanism of SAM formation is found: OPA multilayers, mostly bilayers, are initially deposited on the mica surface. As time passes, these large multilayers break apart and evolve into disorganized monolayers. Following a rapid evolution, such monolayers are found to transform into well-ordered OPA self-assembled monolayers. DA - 2001/12/25/ PY - 2001/12/25/ DO - 10.1021/la010909a VL - 17 IS - 26 SP - 8193-8198 SN - 0743-7463 ER - TY - JOUR TI - Spectroscopic ellipsometric study of the dielectric function of ZnSe and its overlayer AU - Kim, T. J. AU - Koo, M. S. AU - Lee, M. S. AU - Kim, Y. D. AU - Aspnes, D. E. AU - Jonker, B. T. T2 - Journal of the Korean Physical Society DA - 2001/// PY - 2001/// VL - 39 IS - 2001 Dec SP - S372-375 ER - TY - JOUR TI - Load characterization of high displacement piezoelectric actuators with various end conditions AU - Mulling, J AU - Usher, T AU - Dessent, B AU - Palmer, J AU - Franzon, P AU - Grant, E AU - Kingon, A T2 - SENSORS AND ACTUATORS A-PHYSICAL AB - Piezoelectric ceramic transducers are characterized by relatively small strains on the order of 0.1%. One method of achieving significantly larger displacements is to utilize flexural mode actuators, such as unimorphs or bimorphs. In this paper, we investigate a particular type of stressed unimorph flexural actuator, viz. the ‘THUNDER’ actuators. (THUNDER™ is a trademark of Face International Corporation). These stressed unimorphs are of interest due to their particularly large flexural strains. To determine their versatility as high displacement actuators, it was necessary to investigate their actuation capability as a function of load. In addition, our investigation determined that end conditions have an appreciable effect, which has also not been reported in the literature. Therefore, experimental results of the load capabilities of these high displacement actuators with various end conditions are presented here. Commercially available rectangular actuators were chosen for this study. The actuators had been constructed by bonding thin PZT ceramics (0.152 mm thick, 1.37 cm wide, 3.81 cm long) to stainless steel sheets (0.20 mm thick, 1.27 cm wide, 6.35 cm long). They were operated in a flexural mode. It was shown that progressively restrictive end conditions increased the stiffness, ranging from 2.5 to 23 N/m, enhancing the load capabilities of the actuator. In some cases, displacement actually increased as a function of load. This enhanced stiffness was obtained at a cost of reduced no load flexural strain (defined as the ratio of flexural displacement and ceramic length), ranging from 1.08% for free-end conditions to 0.2% for highly restricted end conditions. The load bearing capabilities were tested out to 10 N for most end conditions. DA - 2001/10/31/ PY - 2001/10/31/ DO - 10.1016/S0924-4247(01)00688-4 VL - 94 IS - 1-2 SP - 19-24 SN - 0924-4247 KW - THUNDER transducers KW - piezoelectric KW - actuator KW - ferroelectric KW - PZT KW - unimorph ER - TY - JOUR TI - Fourth-order elastic constants of magnesium oxide AU - Wang, K. AU - Reeber, R. R. AU - Salama, K. T2 - Physica Status Solidi. B, Basic Solid State Physics DA - 2001/// PY - 2001/// VL - 228 IS - 3 SP - 837-845 ER - TY - JOUR TI - Fixed charge and interface traps at heterovalent interfaces between Si(100) and non-crystalline Al2O3-Ta2O5 alloys AU - Johnson, RS AU - Lucovsky, G AU - Hong, JG T2 - MICROELECTRONIC ENGINEERING AB - Characterization by Auger electron spectroscopy, AES, and Fourier transformation infrared spectroscopy, FTIR, confirm that (Ta2O5)x(Al2O3)1−x alloys are homogeneous with pseudo-binary in character, and display increased thermal stability. Capacitance–voltage, C–V, and current density–voltage, J–V, data as a function of temperate show that the Ta d-states of the alloys act as localized electron traps, and are at an energy approximately equal to the conduction band offset of Ta2O5 with respect to Si. DA - 2001/11// PY - 2001/11// DO - 10.1016/S0167-9317(01)00673-6 VL - 59 IS - 1-4 SP - 385-391 SN - 1873-5568 KW - heterovalent interface KW - interface traps KW - fixed charge KW - trapped limited transport ER - TY - JOUR TI - Chemically enhanced focused ion beam micromachining of copper AU - Gonzalez, JC AU - Griffis, DP AU - Miau, TT AU - Russell, PE T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B AB - Chemically enhanced focused ion beam micromachining of thin film Cu on Si substrates has been investigated. Barrier layers and dielectric layers were considered as well. The gases investigated include the Cl containing examples of C2Cl4, C2H4Cl2, and CHCl2CCl3 as well as the oxygen containing gases ethanol, and methanol and water vapor. Crystallographic channeling effect results in nonuniform Cu milling, insufficient selectivity and poor end-point detection. However, the gases investigated were shown to enhance the milling homogeneity, improve the end-point detection, and provide higher selectivity. A Cu/SiO2 selectivity of greater than 4 was obtained when using ethanol as the etching gas. DA - 2001/// PY - 2001/// DO - 10.1116/1.1418406 VL - 19 IS - 6 SP - 2539-2542 SN - 2166-2746 ER - TY - JOUR TI - A molecular orbital model for the electronic structure of transition metal atoms in silicate and aluminate alloys AU - Lucovsky, G AU - Whitten, JL AU - Zhang, Y T2 - MICROELECTRONIC ENGINEERING AB - This paper develops a molecular orbital, MO, model that demonstrates that the electronic structure of non-crystalline oxide dielectrics depends primarily on (i) the coordination and symmetry of transition metal atoms and (ii) the orbital energies of their oxygen neighbors. The calculations indicate that the anti-bonding d-states which determine the minimum energy gap and the conduction band offset energy with respect to Si are a local property of the transition metal–oxygen bonding and are insensitive to second neighbor alloy atoms such as Si or Al. DA - 2001/11// PY - 2001/11// DO - 10.1016/S0167-9317(01)00653-0 VL - 59 IS - 1-4 SP - 329-334 SN - 1873-5568 KW - transition metal silicates and aluminates KW - molecular orbital calculations KW - electronic structure KW - bandgaps KW - band offset energies ER - TY - JOUR TI - Selective bond breaking in amorphous hydrogenated silicon by using Duke FEL AU - Gracin, D AU - Borjanovic, V AU - Vlahovic, B AU - Sunda-Meya, A AU - Patterson, TM AU - Dutta, JM AU - Hauger, S AU - Pinayev, I AU - Ware, ME AU - Alexson, D AU - Nemanich, RJ AU - Roedern, B T2 - NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT AB - In order to study the possibility of influencing the phase containing predominantly Si–H bonds, while having minimal influence on the surrounding materials, samples of a-Si were exposed to Duke-FEL Mark III radiation. The wavelength of the radiation was selected to fit the absorption maximum of stretching vibrations of Si–H bonds (5 μm). By varying the wavelength in the vicinity of 5 μm, the illumination time and the power density, different types and degrees of structural ordering, of Si–H bonds and Si–Si bonds were obtained, and monitored by Raman spectroscopy. By increasing the energy density, at certain level the crystallization occurs. We were able to demonstrate a direct correlation between short and intermediate range ordering and the wavelength and intensity of the radiation. Using 5 μm at 10 kW/cm2 leads to increase in structural disordering. However, increasing power to 60 kW/cm2 improves both short and intermediate order in a-Si : H, as demonstrated by Raman spectroscopy. Further increasing power density by an order of magnitude results in crystallization of the sample. DA - 2001/12/21/ PY - 2001/12/21/ DO - 10.1016/S0168-9002(01)01578-9 VL - 475 IS - 1-3 SP - 635-639 SN - 0168-9002 KW - a-Si : H KW - structure KW - ordering KW - FEL KW - recrystallization KW - raman spectroscopy ER - TY - JOUR TI - Room temperature ferromagnetic properties of (Ga, Mn)N AU - Reed, ML AU - El-Masry, NA AU - Stadelmaier, HH AU - Ritums, MK AU - Reed, MJ AU - Parker, CA AU - Roberts, JC AU - Bedair, SM T2 - APPLIED PHYSICS LETTERS AB - Dilute magnetic semiconductor GaN with a Curie temperature above room temperature has been achieved by manganese doping. By varying the growth and annealing conditions of Mn-doped GaN we have identified Curie temperatures in the range of 228–370 K. These Mn-doped GaN films have ferromagnetic behavior with hysteresis curves showing a coercivity of 100–500 Oe. Structure characterization by x-ray diffraction and transmission electron microscopy indicated that the ferromagnetic properties are not a result of secondary magnetic phases. DA - 2001/11/19/ PY - 2001/11/19/ DO - 10.1063/1.1419231 VL - 79 IS - 21 SP - 3473-3475 SN - 1077-3118 ER - TY - JOUR TI - Tunable magnetic properties of metal ceramic composite thin films AU - Kumar, D AU - Narayan, J AU - Nath, TK AU - Sharma, AK AU - Kvit, A AU - Jin, C T2 - SOLID STATE COMMUNICATIONS AB - We have developed a novel thin film processing method based upon pulsed laser deposition to process nanocrystalline magnetic materials with accurate size and interface control. Using this method, single domain nanocrystalline Fe and Ni particles in 5–10 nm size range embedded in amorphous as well as crystalline alumina have been produced. Magnetization measurements of these layered thin films as function of field and temperature were carried out using a superconducting quantum interference device magnetometer. The size of Fe and Ni nanodots measured using transmission electron microscopy and calculated using magnetic data are in excellent agreement with each other. DA - 2001/// PY - 2001/// DO - 10.1016/S0038-1098(01)00213-7 VL - 119 IS - 2 SP - 63-66 SN - 0038-1098 KW - blocking temperature KW - coercivity KW - nanoscale magnetism KW - nanocrystalline magnetic materials ER - TY - JOUR TI - Strain-induced piezoelectric field effects on light emission energy and intensity from AlInGaN/InGaN quantum wells AU - Aumer, ME AU - LeBoeuf, SF AU - Moody, BF AU - Bedair, SM T2 - APPLIED PHYSICS LETTERS AB - We report on the effects of the piezoelectric field and well width on the transition energy and intensity for InGaN quantum well structures with GaN or AlInGaN quaternary barriers. It was found that the emission energy of compressively strained GaN/In0.08Ga0.92N quantum wells exhibits a strong well width dependence not accounted for by quantum confinement subband energy shifting alone. However, for unstrained quantum well layers with quaternary barriers, no emission energy dependence on width was observed due to the elimination of the piezoelectric field, which was measured to be at least 0.6 MV/cm for the strained quantum wells. Furthermore, the unstrained quantum wells demonstrated a higher intensity than their strained counterparts for all quantum well widths investigated. The current data will help clarify the origin of emission in InGaN quantum wells. DA - 2001/12/3/ PY - 2001/12/3/ DO - 10.1063/1.1418453 VL - 79 IS - 23 SP - 3803-3805 SN - 1077-3118 ER - TY - JOUR TI - Strain and dislocation reduction in maskless pendeo-epitaxy GaN thin films AU - Roskowski, A. M. AU - Miraglia, P. Q. AU - Preble, E. A. AU - Einfeldt, S. AU - Stiles, T. AU - Davis, R. F. AU - Schuck, J. AU - Grober, R. AU - Schwarz, U. T2 - Physica Status Solidi. A, Applications and Materials Science AB - Measurement of strain in GaN films grown via pendeo-epitaxy (PE) indicates that the overgrowth, or wing, material is crystallographically relaxed. An increase of ≈0.02% in the c-axis lattice parameter of the wing material was measured via high-resolution X-ray diffraction (HRXRD); additional evidence for this increase was indicated by an upward shift of the E2 Raman line frequency. Atomic force microscopy studies revealed a reduction in the density of mixed-type dislocations in the wing. A reduction in screw-type dislocations in the wings with respect to the stripes is indicated by a reduction in HRXRD rocking curve FWHM of the (0002) reflections from 646 to 354 arcsec. The off-axis FWHM of the wing area was 126 arcsec compared to 296 arcsec for the stripe indicating a reduction in the edge-type dislocations as well. Pendeo-epitaxy growth of wings off the (110) surface of a GaN stripe produced a material that is crystallographically relaxed, contains fewer defects compared to the stripe and is atomically smooth on the (110) surface. DA - 2001/// PY - 2001/// DO - 10.1002/1521-396x(200112)188:2<729::aid-pssa729>3.0.co;2-w VL - 188 IS - 2 SP - 729-732 ER - TY - JOUR TI - Room temperature magnetic (Ga,Mn)N: a new material for spin electronic devices AU - Reed, ML AU - Ritums, MK AU - Stadelmaier, HH AU - Reed, MJ AU - Parker, CA AU - Bedair, SM AU - El-Masry, NA T2 - MATERIALS LETTERS AB - A new dilute magnetic semiconductor (Ga,Mn)N grown by metal organic chemical vapor deposition (MOCVD) is reported. Vibrating sample magnetometer (VSM) and extraordinary Hall effect (EHE) measurements verified a ferromagnetic component at room temperature. The direction of the easy axis and the Curie temperature varies with the growth conditions, the latter ranging from 38°C to 75°C. Secondary ion mass spectroscopy (SIMS) confirms diffusion of Mn into the GaN to a depth of 380 Å. DA - 2001/12// PY - 2001/12// DO - 10.1016/S0167-577X(01)00342-1 VL - 51 IS - 6 SP - 500-503 SN - 0167-577X KW - magnetic KW - semiconductors KW - Ga-Mn-N ER - TY - JOUR TI - Recovery characteristics of hydrogen-damaged (Pb,La)(Zr,Ti)O-3 capacitors with Pt and IrO2 top electrodes AU - Yoon, SG AU - Kingon, AI T2 - JOURNAL OF THE ELECTROCHEMICAL SOCIETY AB - The effect of hydrogen on ferroelectric properties was investigated for ( Pb , La ) ( Zr , Ti ) O 3 ( PLZT ) films with Pt and IrO 2 top electrodes. The P-E hysteresis loop and fatigue properties of the Pt/PLZT/Pt capacitor are completely recovered by recovery anneal at 700°C in O 2 ambient after a hydrogen-forming gas anneal. On the other hand, IrO 2 / PLZT / Pt capacitor after recovery anneal does not show a complete recovery for ferroelectric properties. The IrO 2 top electrode in the IrO 2 / PLZT / Pt capacitor is completely reduced to Ir metal in 4% H 2 at 300°C and then change to the IrO 2 / Ir complex phase after recovery anneal at 700°C in O 2 ambient. The ferroelectric properties of PLZT capacitors greatly depend on the residual hydrogen near the film/top electrode interface after recovery anneal. © 2001 The Electrochemical Society. All rights reserved. DA - 2001/7// PY - 2001/7// DO - 10.1149/1.1375170 VL - 148 IS - 7 SP - F137-F139 SN - 0013-4651 ER - TY - JOUR TI - LWR pellet-cladding interactions: Materials solutions to SCC AU - Edsinger, K AU - Murty, KL T2 - JOM-JOURNAL OF THE MINERALS METALS & MATERIALS SOCIETY DA - 2001/7// PY - 2001/7// DO - 10.1007/s11837-001-0079-7 VL - 53 IS - 7 SP - 9-13 SN - 1047-4838 ER - TY - JOUR TI - Interfacial and topological measurements of bicontinuous polymer morphologies - art. no. 010803 AU - Jinnai, H. AU - Kajihara, T. AU - Watashiba, H. AU - Nishikawa, Y. AU - Spontak, R. J. T2 - Physica. E, Low-dimensional Systems & Nanostructures DA - 2001/// PY - 2001/// VL - 6401 IS - 1 SP - 0803- ER - TY - JOUR TI - Fracture in ferritic reactor steel - Dynamic strain aging and cyclic loading AU - Murty, KL AU - Seok, CC T2 - JOM-JOURNAL OF THE MINERALS METALS & MATERIALS SOCIETY DA - 2001/7// PY - 2001/7// DO - 10.1007/s11837-001-0082-z VL - 53 IS - 7 SP - 23-26 SN - 1047-4838 ER - TY - JOUR TI - Conventional and pendeo-epitaxial growth of GaN(0001) thin films on Si(111) substrates AU - Davis, RF AU - Gehrke, T AU - Linthicum, KJ AU - Preble, E AU - Rajagopal, P AU - Ronning, C AU - Zorman, C AU - Mehregany, M T2 - JOURNAL OF CRYSTAL GROWTH AB - Single-crystal wurtzitic GaN(0 0 0 1) films have been grown via conventional methods on high-temperature AlN(0 0 0 1) buffer layers previously deposited on 3C-SiC(1 1 1)/Si(1 1 1) substrates using metal organic vapor phase epitaxy (MOVPE). Formation of the 3C-SiC transition layer employed a carburization step and the subsequent deposition of epitaxial 3C-SiC(1 1 1) on the Si(1 1 1) surface using atmospheric pressure chemical vapor deposition (APCVD) for both processes. Similar films, except with significantly reduced dislocation densities, have been grown via pendeo-epitaxy (PE) from the (112̄0) sidewalls of silicon nitride masked, raised, rectangular, and [11̄00] oriented GaN stripes etched from films conventionally grown on similarly prepared, Si-based, multilayer substrates. The FWHM of the (0 0 0 2) X-ray diffraction peak of the conventionally grown GaN was 1443 arcsec. The FWHM of the photoluminescence (PL) spectra for the near band-edge emission on these films was 19 meV. Tilting in the coalesced PE-grown GaN epilayers of 0.2° was confined to the areas of lateral overgrowth over the masks; no tilting was observed in the material suspended above the trenches. The strong, low-temperature PL band-edge peak at 3.456 eV with an FWHM of 17 meV in the PE films was comparable to that observed in PE GaN films grown on AlN/6H-SiC(0 0 0 1) substrates. DA - 2001/10// PY - 2001/10// DO - 10.1016/S0022-0248(01)01462-2 VL - 231 IS - 3 SP - 335-341 SN - 1873-5002 KW - characterization KW - defects KW - dislocations KW - X-ray diffraction KW - selective growth KW - metalorganic chemical vapor deposition metalorganic vapor phase epitaxy KW - pendeoepitaxy KW - gallium compounds KW - nitrides KW - silicon KW - semiconducting gallium compounds KW - scanning electron microscopy KW - transmission electron microscopy ER - TY - JOUR TI - Structure and stability of La2O3/SiO2 layers on Si(001) AU - Stemmer, S AU - Maria, JP AU - Kingon, AI T2 - APPLIED PHYSICS LETTERS AB - High-resolution transmission electron microscopy and electron energy-loss spectroscopy (EELS) were used to investigate La2O3/SiO2/Si structures. The La2O3 layers were deposited on thermal SiO2 on silicon, followed by rapid thermal annealing treatments at 600 °C and 800 °C in a nitrogen ambient. After annealing at 600 °C, the oxide layers were amorphous. After an 800 °C treatment, crystallites appeared in the original La2O3 layer, and the total oxide layer thickness increased by 17%, most likely due to the oxygen diffusion and reaction at the Si/SiO2 interface. EELS, using a 0.2 nm probe, showed that rapid thermal annealing at 600 °C did not cause significant La diffusion into the SiO2 layer, whereas some intermixing was observed at 800 °C. We use the observed microstructures to estimate equivalent oxide thicknesses. The results demonstrate that oxygen partial pressures and initial SiO2 thickness need to be carefully controlled to control SiO2 formation at the Si interface and to achieve target equivalent oxide thickness. DA - 2001/7/2/ PY - 2001/7/2/ DO - 10.1063/1.1383268 VL - 79 IS - 1 SP - 102-104 SN - 0003-6951 ER - TY - JOUR TI - Physical and electrical characterization of ultrathin yttrium silicate insulators on silicon AU - Chambers, JJ AU - Parsons, GN T2 - JOURNAL OF APPLIED PHYSICS AB - This article describes the oxidation of yttrium on silicon to form yttrium silicate films for application as high dielectric constant insulators. The high reactivity of yttrium metal with silicon and oxygen is utilized to form amorphous yttrium silicate films with a minimal interfacial silicon dioxide layer. Yttrium silicate films (∼40 Å) with an equivalent silicon dioxide thickness of ∼11 Å and k∼14 are formed by oxidizing yttrium on silicon. The physical properties of yttrium silicate films on silicon are investigated using x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The oxidation of yttrium silicide results in films nearly identical, although with a higher silicon fraction, to films formed by oxidation of yttrium on silicon. The oxidation of yttrium on silicon results in a competition for yttrium between silicide formation and oxidation. This competition yields yttrium silicate films for thin (&lt;40 Å) initial metal thickness and a Y2O3/silicate bilayer for thick (&gt;80 Å) initial metal thickness. Annealing yttrium films on silicon in vacuum to form yttrium silicide and then oxidizing the silicide is used to eliminate the competition and control the yttrium/silicon reaction. Analysis of the oxidation of yttrium on silicon reveals fast oxidation during silicate formation and a slow rate during oxidation of the silicon substrate to form SiO2. Oxidation of other metals, such as Hf, Zr, and La, on silicon is expected to result in metal silicate films through a similar simultaneous (or controlled sequential) silicide/oxidation reactions. DA - 2001/7/15/ PY - 2001/7/15/ DO - 10.1063/1.1375018 VL - 90 IS - 2 SP - 918-933 SN - 0021-8979 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000169660000057&KeyUID=WOS:000169660000057 ER - TY - JOUR TI - Origins of stored enthalpy in cryomilled nanocrystalline Zn AU - Zhang, XH AU - Wang, HY AU - Kassem, M AU - Narayan, J AU - Koch, CC T2 - JOURNAL OF MATERIALS RESEARCH DA - 2001/12// PY - 2001/12// DO - 10.1557/JMR.2001.0479 VL - 16 IS - 12 SP - 3485-3495 SN - 0884-2914 ER - TY - JOUR TI - Optical metastability of subband gap (2.2 eV) yellow luminescence in GaN AU - Chang, YC AU - Oberhofer, AE AU - Muth, JF AU - Kolbas, RM AU - Davis, RF T2 - APPLIED PHYSICS LETTERS AB - Optical metastability has been studied in undoped GaN films grown on SiC substrates having a previously deposited AlN buffer layer. Brief exposures to a higher intensity ultraviolet light resulted in temporary changes in the optical properties of the GaN layer. The photoinduced changes created high contrast patterns on samples that could be observed under an optical microscope with lower intensity ultraviolet excitation. The subband gap yellow photoluminescence peak at 2.2 eV increased significantly after the patterns were created. This change slowly returned (hours) to its initial value at room temperature. The retention time decreased to a few seconds at temperatures above 100 °C. The data showed that a 1.34 eV thermal activation energy exists, which suggests that the cause of these metastable properties is related to the subband gap yellow luminescence. DA - 2001/7/16/ PY - 2001/7/16/ DO - 10.1063/1.1381417 VL - 79 IS - 3 SP - 281-283 SN - 0003-6951 ER - TY - PAT TI - Methods and apparatus for rapidly prototyping three-dimensional objects from a plurality of layers AU - Cormier, D. R. AU - Taylor, J. B. AU - West, Harvey A., II C2 - 2001/// DA - 2001/// PY - 2001/// ER - TY - JOUR TI - High coercivity and superparamagnetic behavior of nanocrystalline iron particles in alumina matrix AU - Kumar, D AU - Narayan, J AU - Kvit, AV AU - Sharma, AK AU - Sankar, J T2 - JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS AB - Single-domain nanoscale magnetic iron particles have been embedded uniformly in an amorphous matrix of alumina using a pulsed laser deposition technique. Structural characterization by transmission electron microscopy (TEM) reveals the presence of a crystalline iron and an amorphous alumina phase. Fine particle magnetism have been investigated by carrying out field and temperature dependence of magnetization measurements using superconducting quantum interference device magnetometer. The particle size of Fe in Al2O3 matrices prepared by changing the deposition time of Fe, have been found to be 9, 7 and 5 nm from TEM studies. At 10 K, the coercivities of these samples are found be 450, 350 and 150 Oe, respectively. At 300 K, the coercivity of Fe–Al2O3 sample decreases from 100 to 50 Oe as the particle size decreases from 9 to 7 nm and finally the sample turns superparamagnetic when the Fe particle size becomes around 5 nm. Based on the calculated value of blocking temperature, TB, (481 K), magnetic anisotropy K (4.8×105 erg/cm3) for Fe, and the Boltzmann constant kB (1.38×10−16 erg/K) from TB=KV/25kB, the mean radius of Fe particles is found to be 9.3 nm. in one of the samples. This is in good agreement with the particle size measured using TEM studies. DA - 2001/7// PY - 2001/7// DO - 10.1016/S0304-8853(01)00191-3 VL - 232 IS - 3 SP - 161-167 SN - 1873-4766 KW - nanoscale magnetism KW - coercivity KW - superparamagnetism KW - pulsed laser deposition ER - TY - JOUR TI - Growth of epitaxial CoSi2 on 6H-SiC(0001)(Si) AU - Platow, W AU - Nemanich, RJ AU - Sayers, DE AU - Hartman, JD AU - Davis, RF T2 - JOURNAL OF APPLIED PHYSICS AB - Epitaxial growth of (111)-oriented CoSi2 has been achieved on a scratch-free 6H-SiC(0001)Si substrate. The surface was prepared using atmospheric hydrogen etching and ultrahigh vacuum Si cleaning. A high-quality CoSi2 thin film was obtained by a modified template method and co-deposition of Co and Si at 550 °C. The structure and morphology of the film is studied by means of reflection high electron energy diffraction, x-ray absorption fine structure, x-ray diffraction, and atomic force microscopy. DA - 2001/12/15/ PY - 2001/12/15/ DO - 10.1063/1.1412842 VL - 90 IS - 12 SP - 5924-5927 SN - 1089-7550 ER - TY - JOUR TI - Electronic structure, amorphous morphology and thermal stability of transition metal oxide and chalcogenide alloys AU - Lucovsky, G. T2 - Journal of Optoelectronics and Advanced Materials DA - 2001/// PY - 2001/// VL - 3 IS - 2 SP - 155-166 ER - TY - JOUR TI - Consequence of nanometer-scale property variations to macroscopic properties of CrOCN thin films AU - Smith, J AU - French, RH AU - Duscher, G AU - Bonnell, D T2 - JOURNAL OF THE AMERICAN CERAMIC SOCIETY AB - Macroscopic properties of CrOCN thin films are related directly to composition and property variations on multiple length scales. Compositions resolved on a nanometer scale were measured in‐depth in 120–150 nm thick CrOCN films by sputtered neutral mass spectroscopy. A statistical analysis of composition identifies the particular coordinations of the various anions with Cr that form preferentially under relevant processing conditions. Near‐edge structure in electron energy loss from transmission electron microscopy and the Cr core level shift in X‐ray photoemission spectroscopy further support this conclusion. A wide range of compositions are described in terms of mixtures of binary and ternary compounds, and optical absorption is found to be correlated with the presence of Cr 4+ within this description. It appears that the presence of the unfilled t2g state is responsible for optical absorption in the range of 0.5–6 eV and that a critical concentration of Cr 4+ in certain species within the system is required for the transition to occur. These results conflict with the suggestion that a percolated network of metallic clusters is responsible for the change in properties. DA - 2001/12// PY - 2001/12// DO - 10.1111/j.1151-2916.2001.tb01108.x VL - 84 IS - 12 SP - 2873-2881 SN - 0002-7820 ER - TY - JOUR TI - Ca- and Sr-doped (Pb1-xLax)(ZryTi1-y)(1-x/4)O-3 thin films for low-voltage operation AU - Kim, S. H. AU - Ha, J. AU - Hwang, C. S. AU - Kingon, A. I. T2 - Thin Solid Films DA - 2001/// PY - 2001/// VL - 394 IS - 1-2 SP - 131-135 ER - TY - JOUR TI - Above bandgap optical properties of ZnS and ZnS1-xTex alloys grown by using hot-wall epitaxy AU - Bang, C. Y. AU - Lee, M. S. AU - Kim, T. J. AU - Kim, Y. D. AU - Aspnes, D. E. AU - Yu, Y. M. AU - O, B. S. AU - Choi, Y. D. T2 - Journal of the Korean Physical Society DA - 2001/// PY - 2001/// VL - 39 IS - 3 SP - 462-465 ER - TY - JOUR TI - Thickness effects on imprint in chemical-solution-derived (Pb, La)(Zr, Ti)O-3 thin films AU - Kim, SH AU - Woo, HJ AU - Ha, J AU - Hwang, CS AU - Kim, HR AU - Kingon, AI T2 - APPLIED PHYSICS LETTERS AB - The film thickness-dependent imprinting behavior (voltage shift) of (Pb, La)(Zr, Ti)O3 capacitors was evaluated by a thermal stress process under a remanence bias. The remanent polarization (Pr) was found to be almost independent of the film thickness whereas in the 50–300 nm range the relative dielectric constant (εr) increased linearly with the square root of the film thickness. It was found that the voltage shift, which was attributed to the accumulation of charged defects near the electrode interface, also increased linearly with increasing film thickness. In addition, the charge accumulated thickness varied with the square root of the film thickness. This was established from a simple assumption that the level of charge accumulation is determined by the product of the total amount of charged defects (total film thickness×charged defect density) and the internal field that is generated by the Pr. Therefore, the imprint is much more a bulk-related degradation phenomenon compared to the fatigue. DA - 2001/5/7/ PY - 2001/5/7/ DO - 10.1063/1.1370989 VL - 78 IS - 19 SP - 2885-2887 SN - 1077-3118 ER - TY - JOUR TI - Relaxation of InGaN thin layers observed by x-ray and transmission electron microscopy studies AU - Liliental-Weber, Z AU - Benamara, M AU - Washburn, J AU - Domagala, JZ AU - Bak-Misiuk, J AU - Piner, EL AU - Roberts, JC AU - Bedair, SM T2 - JOURNAL OF ELECTRONIC MATERIALS DA - 2001/4// PY - 2001/4// DO - 10.1007/s11664-001-0056-5 VL - 30 IS - 4 SP - 439-444 SN - 0361-5235 KW - InGaN KW - strained layer KW - relaxed layer KW - planar defects KW - TEM KW - x-rays ER - TY - JOUR TI - Process optimization in the low-pressure flat flame growth of diamond AU - Wolter, SD AU - Schlesser, R AU - Okuzumi, F AU - Prater, JT AU - Sitar, Z T2 - DIAMOND AND RELATED MATERIALS AB - Abstract The influence of oxy-acetylene gas mixture (O 2 /C 2 H 2 gas ratio — 0.95:1.06) and substrate temperature (ranging from 650 to 850°C) on diamond growth in the low-pressure flat flame is reported. Deconvolution of the Raman spectra was employed to qualitatively estimate the ratio of diamond-to-non-diamond carbon in the film deposits by an area comparison of these discriminate peaks. The diamond crystallinity was assessed quantitatively by a determination of the full-width-at-half-maximum of the 1332 cm −1 Raman line representing sp 3 -bonded carbon. An optimum oxygen/acetylene molar ratio of ∼1.05 and substrate temperature of 650–750°C were observed for limiting both the non-diamond carbon content and a deterioration in the diamond crystallinity. The crystallite morphology was also evaluated as a function of this same parametric regime based on assignment of the parameter α describing growth rate competition between the {100} and {111} faces. The collective data indicates the process conditions required to produce the optimum in film quality according to a desired film morphology. DA - 2001/// PY - 2001/// DO - 10.1016/S0925-9635(00)00477-5 VL - 10 IS - 3-7 SP - 289-294 SN - 0925-9635 KW - diamond deposition KW - combustion growth KW - morphology KW - Raman spectroscopy ER - TY - JOUR TI - Phase formation and stability in reactively sputter deposited yttria-stabilized zirconia coatings AU - Ji, ZQ AU - Haynes, JA AU - Voelkl, E AU - Rigsbee, JM T2 - JOURNAL OF THE AMERICAN CERAMIC SOCIETY AB - Yttria‐stabilized zirconia (YSZ) coatings were produced by reactively cosputtering metallic zirconium and yttrium targets in an argon and oxygen plasma using a system with multiple magnetron sputtering sources. Coating crystal structure and phase stability, as functions of Y 2 O 3 content, substrate bias, and annealing temperature, were investigated by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Results demonstrated that highly (111)‐oriented tetragonal and cubic zirconia structures were formed in 2 and 4.5 mol% Y 2 O 3 coatings, respectively, when the coatings were grown with an applied substrate bias. Conversely, coatings deposited with no substrate bias had random tetragonal and cubic structures. XRD analysis of annealed coatings showed that the cubic zirconia in 4.5 mol% Y 2 O 3 coatings exhibited structural stability at temperatures up to 1200°C. Transformation of the tetragonal to monoclinic phase occurred in 2 mol% Y 2 O 3 coating during high‐temperature annealing, with the fraction of transformation dependent on bias potential and annealing temperature. DA - 2001/5// PY - 2001/5// DO - 10.1111/j.1151-2916.2001.tb00770.x VL - 84 IS - 5 SP - 929-936 SN - 1551-2916 ER - TY - JOUR TI - Pendeo-epitaxial growth of thin films of gallium nitride and related materials and their characterization AU - Davis, RF AU - Gehrke, T AU - Linthicum, KJ AU - Zheleva, TS AU - Preble, EA AU - Rajagopal, P AU - Zorman, CA AU - Mehregany, M T2 - JOURNAL OF CRYSTAL GROWTH AB - Monocrystalline GaN and AlxGa1−xN films have been grown via the pendeo-epitaxy (PE)1 technique with and without Si3N4 masks on GaN/AlN/6H-SiC(0 0 0 1) and GaN(0 0 0 1)/AlN(0 0 0 1)/3C-SiC(1 1 1)/Si(1 1 1) substrates using organometallic vapor phase deposition. Scanning and transmission electron microscopies were used to evaluate the external microstructures and the distribution of dislocations, respectively. The dislocation densities in the PE grown films were reduced at least five orders of magnitude relative to the initial GaN seed layers. Tilting to 0.2° in the portion of the coalesced GaN epilayers grown over the silicon nitride masks was observed via X-ray diffraction. Neither tilting nor low angle boundaries were observed within areas of coalescence in the material grown on substrates without the masks. The strong, low-temperature PL band-edge peak at 3.45 eV with a FWHM of 17 meV was comparable to that observed in PE GaN films grown on 6H-SiC(0 0 0 1). The band-edge in the GaN grown on AlN(0 0 0 1)/SiC(1 1 1)Si(1 1 1) substrates was shifted to a lower energy by 10 meV, indicative of a greater tensile stress. DA - 2001/5// PY - 2001/5// DO - 10.1016/S0022-0248(01)00836-3 VL - 225 IS - 2-4 SP - 134-140 SN - 0022-0248 KW - crystal morphology KW - defects KW - interfaces KW - pendeoepitaxy KW - nitrides KW - semiconducting gallium compounds ER - TY - JOUR TI - Ordinary and extraordinary dielectric functions of 4H-and 6H-SiC from 3.5 to 9.0 eV AU - Lindquist, OPA AU - Jarrendahl, K AU - Peters, S AU - Zettler, JT AU - Cobet, C AU - Esser, N AU - Aspnes, DE AU - Henry, A AU - Edwards, NV T2 - APPLIED PHYSICS LETTERS AB - We report ordinary (ε⊥c axis) and extraordinary (ε∥c axis) dielectric function data of 4H– and 6H–SiC from 3.5 to 9.0 eV. These data, which were obtained by with spectroscopic ellipsometry, are also compared to recently reported ab initio calculations. Critical point energies were found using real and reciprocal space analysis. DA - 2001/4/30/ PY - 2001/4/30/ DO - 10.1063/1.1369617 VL - 78 IS - 18 SP - 2715-2717 SN - 0003-6951 ER - TY - JOUR TI - Kinetics and gas-surface dynamics of GaN homoepitaxial growth using NH3-seeded supersonic molecular beams AU - McGinnis, AJ AU - Thomson, D AU - Davis, RF AU - Chen, E AU - Michel, A AU - Lamb, HH T2 - SURFACE SCIENCE AB - The kinetics of homoepitaxial growth of GaN thin films on metal-organic chemical vapor deposition (MOCVD)-grown GaN(0 0 0 1)/AlN/6H-SiC substrates was probed using NH3-seeded supersonic molecular beams. NH3 was seeded in H2 and He and antiseeded in N2 and Ar in order to obtain incident kinetic energies of 0.08–1.8 eV. Nozzle temperatures of 35–600 °C were used to adjust the NH3 internal energy. Intense NH3 beams (fluxes >2×1015cm−2s−1 at the substrate) are produced for low seeding percentages (<5%) in the lighter carrier gases, because the heavier species (NH3) is focused along the centerline of the beam. The NH3 flux is proportional to the ratio of its molecular weight to the average molecular weight of the binary gas mixture. A steady-state Langmuir–Hinshelwood kinetics model was used to extract zero-coverage NH3 sticking coefficient (αNH30) values from GaN growth kinetics data. An αNH30 value of 0.14 at 750 °C was determined using seeded supersonic beams of NH3 in He with incident kinetic energies of 0.4–0.5 eV. In comparison, GaN growth rates using low-energy NH3 molecules (0.03 eV) from a leak valve indicate an αNH30 of 0.29. Growth rate measurements using NH3 beams with kinetic energies of 0.08–1.8 eV confirmed that αNH30 generally decreases with increasing incident kinetic energy, leading us to conclude that NH3 chemisorption on GaN(0 0 0 1) is unactivated and occurs via a precursor-mediated mechanism. Internal energy enhancement of NH3 chemisorption via a precursor-mediated channel is proposed to explain the effects of nozzle temperature on GaN growth kinetics. The effects of NH3 incident kinetic energy on film morphology are indirect. Rough, highly faceted films are observed under Ga-limited growth conditions. The surface morphology of films grown under NH3-limited conditions changes from rough to smooth as the effective V/III ratio is decreased. DA - 2001/11/10/ PY - 2001/11/10/ DO - 10.1016/S0039-6028(01)01466-2 VL - 494 IS - 1 SP - 28-42 SN - 1879-2758 KW - gallium nitride KW - epitaxy KW - ammonia KW - chemisorption KW - adsorption kinetics KW - growth KW - surface structure, morphology, roughness, and topography ER - TY - JOUR TI - Influence of coating strain on calcium phosphate thin-film dissolution AU - Burke, EM AU - Haman, JD AU - Weimer, JJ AU - Cheney, AB AU - Rigsbee, JM AU - Lucas, LC T2 - JOURNAL OF BIOMEDICAL MATERIALS RESEARCH AB - The success of calcium phosphate (CaP) coatings used to accelerate initial bone growth onto dental implants can vary depending on the CaP phases present in the coating. In this study, the effect of CaP coating crystal structure and morphology on dissolution rates was investigated. RF magnetron-sputtered CaP coatings (NTC) were compared to a less strained coating (HTC) obtained from heat treatment of sputtered samples at 550°C. Coating strain differences were apparent in XRD spectra where hydroxyapatite-like planes shifted by 0.5° 2θ and 0.05° 2θ for the NTC and HTC coatings, respectively. HTC XRD peak widths were broader than NTC peak widths, indicating smaller crystals or grain sizes. These differences in grain size were corroborated by imaging with scanning probe microscopy. NTC coatings dissolved at a 300% faster rate than HTC coatings. A major factor contributing to this kinetic effect was the level of strain in both coatings. These results suggest an alternate design for CaP coatings can be obtained through the manipulation of coating strain. Using this approach, delivery of different ionic gradients from CaP coatings to surrounding tissue environments can be obtained from surfaces having similar chemistries. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res 57: 41–47, 2001 DA - 2001/10// PY - 2001/10// DO - 10.1002/1097-4636(200110)57:1<41::AID-JBM1139>3.0.CO;2-9 VL - 57 IS - 1 SP - 41-47 SN - 0021-9304 KW - calcium phosphate coatings KW - dissolution KW - RF sputtering KW - AFM KW - XRD ER - TY - JOUR TI - Improved network development in bidisperse AB/ABA block copolymer gels AU - Spontak, RJ AU - Wilder, EA AU - Smith, SD T2 - LANGMUIR AB - Blending a B-selective solvent and an ordered ABA triblock copolymer can, at sufficiently high solvent concentrations, produce a physical gel composed of a network of B midblocks stabilized by A-rich micelles. We demonstrate here that addition of short AB diblock copolymer molecules to such a gel at constant copolymer composition can enhance the solid-like character of the gel, as indicated by an increase in the magnitude of the dynamic elastic modulus. Similarly, addition of AB molecules to a nongelled ABA/solvent system can induce gelation. In light of recent theoretical predictions and related experimental evidence, these results are consistent with a scenario in which tail-induced volume exclusion (due to the presence of AB molecules) within the micellar coronas improves network development through an increase in the population of bridged B midblocks. DA - 2001/4/17/ PY - 2001/4/17/ DO - 10.1021/la0015819 VL - 17 IS - 8 SP - 2294-2297 SN - 0743-7463 ER - TY - JOUR TI - Growth of highly textured yttria-stabilized zirconia thin film by reactive magnetron sputtering AU - Ji, Z AU - Rigsbee, JM T2 - JOURNAL OF MATERIALS SCIENCE LETTERS DA - 2001/// PY - 2001/// DO - 10.1023/A:1010961115476 VL - 20 IS - 7 SP - 611-613 SN - 0261-8028 ER - TY - JOUR TI - Evidence for the formation mechanism of nanoscale microstructures in cryomilled Zn powder AU - Zhang, X AU - Wang, H AU - Narayan, J AU - Koch, CC T2 - ACTA MATERIALIA AB - Nanocrystalline Zn powder has been synthesized by a cryomilling method. The average grain size decreased exponentially with the cryomilling time and reached a minimum average grain size of around 17 nm. Large numbers of small grains (2∼6 nm) have been found in the very early stages of cryomilling. Dynamic recrystallization was used to explain the observed phenomena. The exothermic peaks revealed in the differential scanning calorimetry (DSC) results were correlated with the release of microstrain as confirmed by the x-ray diffraction measurements. DA - 2001/5/8/ PY - 2001/5/8/ DO - 10.1016/S1359-6454(01)00051-9 VL - 49 IS - 8 SP - 1319-1326 SN - 1873-2453 KW - cryomilling ER - TY - JOUR TI - Cu, Nb and V on (110) TiO2 (rutile): epitaxy and chemical reactions AU - Wagner, T AU - Marien, J AU - Duscher, G T2 - THIN SOLID FILMS AB - Thin metal films on oxide substrates are used in a variety of technological applications including microelectronic devices, catalysts and sensors. Ideally, the films should have low defect densities. This prerequisite can often be fulfilled by growing epitaxial films. Recently, epitaxial films have received a great deal of attention for fundamental studies of the structure and bonding of heterophase interfaces. In this paper, fundamental investigations of the interface formation for MBE deposited metals (Cu, Nb, V) on TiO2 single crystals (rutile) will be presented. The structure and chemical composition of the metal/oxide interfaces were determined by a variety of surface science and transmission electron microscopy methods. We conclude on general trends, which allow the prediction of the growth behavior of metals on oxides as a function of processing and material parameters. DA - 2001/11/1/ PY - 2001/11/1/ DO - 10.1016/S0040-6090(01)01351-7 VL - 398 SP - 419-426 SN - 1879-2731 KW - molecular beam epitaxy KW - metal-oxide interfaces KW - transmission electron microscopy KW - electron energy loss spectrometry ER - TY - JOUR TI - Carbon nanotube composites synthesized by ion-assisted pulsed laser deposition AU - Sharma, AK AU - Kalyanaraman, R AU - Narayan, RJ AU - Oktyabrsky, S AU - Narayan, J T2 - MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY AB - We have synthesized thin CNx films on Si (100) substrate at high temperatures (600 and 700°C) by nitrogen ion-assisted pulsed laser deposition (PLD). The bonding characteristics and microstructure determinations have been accomplished using X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM), respectively. The radial distribution function (RDF) analysis of the electron diffraction patterns was performed to determine the short range atomic order in these films. The results reveal the presence of carbon predominantly in the trigonally-coordinated state with small fractions of nitrogen (upto 20 at.%) bonded to carbon. The electron diffraction and the high resolution images in cross-section view reveal that there is a textured growth of nanotube or graphite-like ribbons. The plan-view specimens show high resolution images with bended layers similar to that of onion or nanotube like features. The kinetics of the ions assisting the growth is assumed to be important to grow the basal planes (00l) of graphite perpendicular to the substrate. The large anisotropic surface energies in two perpendicular directions in graphite suggest that ions can create nonequilibrium conditions to alter the growth mode of graphitic planes. The importance of ion-assisted PLD to grow novel nanotube or fullerenelike structure in the form of thin film composites for electron field emission devices is emphasized. DA - 2001/1/22/ PY - 2001/1/22/ DO - 10.1016/s0921-5107(00)00558-4 VL - 79 IS - 2 SP - 123-127 SN - 0921-5107 KW - carbon nanotube composites KW - ion-assisted pulsed laser deposition KW - X-ray photoelectron spectroscopy ER - TY - JOUR TI - Asymmetric nanoscale switching in ferroelectric thin films by scanning force microscopy AU - Gruverman, A AU - Kholkin, A AU - Kingon, A AU - Tokumoto, H T2 - APPLIED PHYSICS LETTERS AB - Scanning force microscopy (SFM) has been used to perform nanoscale studies of the switching behavior of Pb(Zr, Ti)O3 thin films via the direct observation of their domain structures. The study revealed a significant asymmetry of a switching pattern which is a function of the voltage polarity and original domain structure of individual grains. The phenomenon of asymmetric switching is attributed (1) to the presence of an internal built-in electric field at the bottom interface and (2) to the mechanical stress exerted by the SFM tip. The former effect results in incomplete 180° switching, while the latter effect leads to a 90° rotation of the polarization vector. The resulting shear stress deformation of the grain underneath the tip combined with the applied field effect propels polarization reversal in the adjacent grains. DA - 2001/4/30/ PY - 2001/4/30/ DO - 10.1063/1.1366644 VL - 78 IS - 18 SP - 2751-2753 SN - 1077-3118 ER - TY - JOUR TI - XAFS studies of the formation of cobalt silicide on (root 3 x root 3) SiC(0001) AU - Platow, W AU - Wood, DE AU - Burnette, JE AU - Nemanich, RJ AU - Sayers, DE T2 - JOURNAL OF SYNCHROTRON RADIATION AB - Thin Co films (1-8 nm) were directly, sequentially, and co-deposited with Si (3.6-29.2 nm) on the (square root of 3 x square root of 3)-R30 degrees reconstruction of 6H-SiC(0001). The films were annealed over a temperature range of 823-1373K and investigated with XAFS, XPS, AES and AFM. After annealing up to 1373K directly deposited Co films do not transform entirely to cobalt disilicide and C segregation is observed on the surface of the films. On the other hand, sequentially and co-deposited films do form cobalt disilicide after annealing at 823K, but also show islanding after annealing at 923K. DA - 2001/3// PY - 2001/3// DO - 10.1107/S0909049500017921 VL - 8 SP - 475-477 SN - 0909-0495 KW - cobalt silicide KW - silicon carbide KW - metal-semiconductor contacts KW - molecular beam epitaxy ER - TY - JOUR TI - Theoretical analysis of phase-matched second-harmonic generation and optical parametric oscillation in birefringent semiconductor waveguides AU - Dimmock, JO AU - Madarasz, FL AU - Dietz, N AU - Bachmann, KJ T2 - APPLIED OPTICS AB - We analyze the phase-matching conditions for second-harmonic generation (SHG) and optical parametric oscillation (OPO) in birefringent nonlinear semiconductor waveguides and apply these results to the model system of ZnGeP2 on a GaP substrate. The analyses and numerical results show that phase matching can be achieved for OPO and SHG for reasonable guide thicknesses throughout much of the infrared, indicating significant potential applications for nonlinear birefringent waveguides. For the fundamental mode of a relatively thick guide the region of phase matching and the phase-matching angles are similar to those in bulk material. However, the waveguide has the added flexibility that phase-matched coupling can occur between the various modes of the guide. For example, the phase-matching region for SHG can be considerably extended by coupling the pump into the guide in the fundamental, m = 0, mode and phase matching to the m = 2 mode of the second harmonic. Significantly, the results indicate, among other things, that ZnGeP2 waveguides with harmonic output in the m = 2 mode can be used for efficient SHG from input radiation in the 9.6-10.6-microm region where bulk efficiencies in this wavelength range are too small to be useful. DA - 2001/3/20/ PY - 2001/3/20/ DO - 10.1364/AO.40.001438 VL - 40 IS - 9 SP - 1438-1441 SN - 2155-3165 ER - TY - JOUR TI - Photoluminescence and electrical characteristics of the two-dimensional electron gas in Si delta-doped GaN layers AU - Teng, CW AU - Aboelfotoh, MO AU - Davis, RF AU - Muth, JF AU - Kolbas, RM T2 - APPLIED PHYSICS LETTERS AB - We have studied the electrical and photoluminescence (PL) properties of a Si delta-doped GaN layer grown by metalorganic chemical vapor deposition. The Hall mobility and electron sheet concentration are 726 cm2/V s and 1.9×1012 cm−2, respectively, at 2 K. A PL peak located at 78 meV below the band gap of GaN is observed at 77 K. This PL peak is attributed to the radiative recombination between electrons in the two-dimensional quantum states and photoexcited holes in GaN, which is consistent with simulation results using a one-dimensional Poisson and Schrödinger equation solver. The peak disappears at temperatures higher than 77 K and is not observed in uniformly doped GaN layers. DA - 2001/3/19/ PY - 2001/3/19/ DO - 10.1063/1.1353836 VL - 78 IS - 12 SP - 1688-1690 SN - 1077-3118 ER - TY - JOUR TI - Optimizing high-current yields from diamond coated field emitters AU - Zhirnov, , VV AU - Lizzul-Rinne, C AU - Wojak, GJ AU - Sanwald, RC AU - Cuomo, JJ AU - Hren, JJ T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B AB - The data for the maximum emission currents from needle-shaped emitters with differing diamond coatings were empirically analyzed. The coatings studied were chemical vapor deposition diamond, natural diamond, and nanodiamond. Two parameters were chosen to characterize the emissive properties: (1) the dependence of the maximum current (Imax) on the coating thickness (D), i.e., I(D)=ΔImax/ΔD, and (2) the dependence of the threshold voltage Vth on [(D);ΔVth/ΔD]. The dependence of Imax(D) and Imax/Vmax(D) were determined from the experimental data for the three different diamond coatings. The maximum current Imax is very different for these three different coatings and is also a function of the coating thickness, D. Both the maximum current and the transconductance of field emission tips can be increased significantly by diamond coatings. A strong, nearly linear, dependence of Imax on diamond thickness was found. An empirical estimate of the thermal conductivity of nanodiamond, based on the field emission data, gave 2.71 W/cm K. The maximum current output from multitip arrays was also analyzed and an optimization procedure was devised that suggested a route to “engineered coatings.” DA - 2001/// PY - 2001/// DO - 10.1116/1.1340009 VL - 19 IS - 1 SP - 17-22 SN - 1071-1023 ER - TY - JOUR TI - On the imaging mechanism of ferroelectric domains in scanning force microscopy AU - Gruverman, A AU - Tokumoto, H T2 - NANO LETTERS AB - Scanning force microscopy (SFM) studies of the domain structure in ferroelectric thin films on a nonmetal substrate allowed direct assessment of the electrostatic mechanism contribution to the domain contrast in the SFM contact mode. It has been shown that the polarization charges of the ferroelectric film are effectively compensated. This result suggests secondary effect of the electrostatic tip−sample interaction on domain imaging mechanism in ferroelectric thin films in contact SFM compared to the major contribution of the piezoelectric effect. DA - 2001/2// PY - 2001/2// DO - 10.1021/nl005522r VL - 1 IS - 2 SP - 93-95 SN - 1530-6984 ER - TY - JOUR TI - Influence of an external electric field during quenching on the hardenability of steel AU - Zheng, M AU - Lu, XP AU - Conrad, H T2 - SCRIPTA MATERIALIA AB - Deep cryogenic heat treatment is a supplementary process, which is performed in tool steels after quench and before temper regularly. In this study, the effect of the electric current flow through the deep cryogenically treated samples was investigated via the X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscope (EDX), hardness test, and pin-on-disk wear testing machine. Results showed that the deep cryogenic heat treatment improves the carbide percentage, distribution, hardness and wear resistance of the 1.2080 tool steel, as compared with those of the conventionally treated. Further improvement in the wear resistance and hardness were also observed due to the formation of some newly formed nano-sized carbides in the structure. It was also observed that the electric current flow leads to a decrease in this improvement due to its effect on the as-quench vacancies, which were ignored as powerful places for carbide nucleation during the deep cryogenic heat treatment. It was also shown that the predominant wear mechanism is a combination of adhesive and tribo-chemical wear. DA - 2001/2/2/ PY - 2001/2/2/ DO - 10.1016/S1359-6462(00)00608-4 VL - 44 IS - 2 SP - 381-385 SN - 1359-6462 KW - steel KW - phase transformation KW - hardenability KW - electric field quenching ER - TY - JOUR TI - High temperature stability in lanthanum and zirconia-based gate dielectrics AU - Maria, JP AU - Wicaksana, D AU - Kingon, AI AU - Busch, B AU - Schulte, H AU - Garfunkel, E AU - Gustafsson, T T2 - JOURNAL OF APPLIED PHYSICS AB - Gate dielectrics composed primarily of lanthana and zirconia were prepared by reactive evaporation. The stability of the layers during high temperature anneals was investigated. By controlling the oxygen partial pressure during heat treatment, lanthana and zirconia films could be protected against reaction with the underlying Si substrate and against the growth of low-ε interface layers. The electrical thickness of the dielectrics could be maintained after a 900 °C exposure. The critical oxygen pressure at 900 °C for low-ε interface formation beneath ZrO2 and La2O3 dielectrics was ∼2e−4 Torr. The interfaces that formed beneath the ZrO2 and La2O3 layers are distinctly different. The sub-ZrO2 interface, influenced primarily by phase separation, tends towards pure SiO2, while the sub-La2O3 interface, influenced primarily by silicate formation, tends towards a La–Si–O alloy. For both materials, reducing the oxygen pressure to values below 10−7 Torr resulted in rapid degradation of the metal oxide. This dielectric degradation is believed to be linked to SiO evaporation. These results suggest that at high temperatures, a window of optimal oxygen partial pressure exists in which the stability of many oxides in contact with silicon can be achieved. DA - 2001/10/1/ PY - 2001/10/1/ DO - 10.1063/1.1391418 VL - 90 IS - 7 SP - 3476-3482 SN - 0021-8979 ER - TY - JOUR TI - Field emission from ultrathin coatings of AlN on Mo emitters AU - Kang, D AU - Zhirnov, , VV AU - Sanwald, RC AU - Hren, JJ AU - Cuomo, JJ T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B AB - Experiments characterizing both the physics of emission and the performance of Mo tips coated with ultrathin film of AlN were conducted. Ultrathin films of AlN with thicknesses ranging from 7 to 21 nm in 1.5 nm increments were deposited onto Mo tips by magnetron sputtering. In situ field emission measurements were performed after each deposition step. Tip radius, thickness, and morphology of AlN coating were characterized with the transmission electron microscopy. The effect of the thickness of AlN on emission was determined using a Fowler–Nordheim analysis. Various surface treatment effects were studied and measurements of maximum current and emission stability were performed, e.g., maximum current from a single Mo tip with 15 nm of AlN coating was 52 μA. DA - 2001/// PY - 2001/// DO - 10.1116/1.1340669 VL - 19 IS - 1 SP - 50-54 SN - 2166-2746 ER - TY - JOUR TI - Epitaxial Pb(Mg1/3Nb2/3)O-3-PbTiO3 thin films grown by MOCVD AU - Baumann, P. K. AU - Streiffer, S. K. AU - Bai, G. R. AU - Ghosh, K. AU - Auciello, O. AU - Thompson, C. AU - Stemmer, S. AU - Rao, R. A. AU - Eom, C. B. AU - Xu, F. AU - Trolier-McKinstry, S. AU - Kim, D. J. AU - Maria, J. P. AU - Kingon, A. I. T2 - Integrated Ferroelectrics DA - 2001/// PY - 2001/// VL - 35 IS - 1-4 SP - 1881-1888 ER - TY - JOUR TI - Electronic structure of noncrystalline transition metal silicate and aluminate alloys AU - Lucovsky, G AU - Rayner, GB AU - Kang, D AU - Appel, G AU - Johnson, RS AU - Zhang, Y AU - Sayers, DE AU - Ade, H AU - Whitten, JL T2 - APPLIED PHYSICS LETTERS AB - A localized molecular orbital description (LMO) for the electronic states of transition metal (TM) noncrystalline silicate and aluminate alloys establishes that the lowest conduction band states are derived from d states of TM atoms. The relative energies of these states are in agreement with the LMO approach, and have been measured by x-ray absorption spectroscopy for ZrO2–SiO2 alloys, and deduced from an interpretation of capacitance–voltage and current–voltage data for capacitors with Al2O3–Ta2O5 alloy dielectrics. The LMO model yields a scaling relationship for band offset energies providing a guideline for selection of gate dielectrics for advanced Si devices. DA - 2001/9/17/ PY - 2001/9/17/ DO - 10.1063/1.1404997 VL - 79 IS - 12 SP - 1775-1777 SN - 0003-6951 ER - TY - JOUR TI - Electrical properties of Ru and RuO2 gate electrodes for Si-PMOSFET with ZrO2 and Zr-silicate dielectrics AU - Zhong, HC AU - Heuss, G AU - Suh, YS AU - Misra, V AU - Hong, SN T2 - JOURNAL OF ELECTRONIC MATERIALS DA - 2001/12// PY - 2001/12// DO - 10.1007/s11664-001-0164-2 VL - 30 IS - 12 SP - 1493-1498 SN - 1543-186X KW - Ru KW - RuO2 KW - ZrO2 KW - Zr-silicate KW - MOS KW - dielectrics KW - gate electrodes ER - TY - JOUR TI - Electrical properties of Pb1-xLax(ZryTi1-y)(1-x/4)O-3 thin films with various iridium-based top electrodes AU - Yoon, S. G. AU - Kingon, A. I. AU - Kim, S. H. T2 - Integrated Ferroelectrics DA - 2001/// PY - 2001/// VL - 33 IS - 1-4 SP - 155-164 ER - TY - JOUR TI - Effects of surface pretreatments on interface structure during formation of ultra-thin yttrium silicate dielectric films on silicon AU - Chambers, JJ AU - Busch, BW AU - Schulte, WH AU - Gustafsson, T AU - Garfunkel, E AU - Wang, S AU - Maher, DM AU - Klein, TM AU - Parsons, GN T2 - APPLIED SURFACE SCIENCE AB - X-ray photoelectron spectroscopy (XPS) and medium energy ion scattering (MEIS) are used to determine chemical bonding and composition of ultra-thin films of mixed yttrium, silicon, and oxygen, formed by oxidation of metal on clean and pre-treated silicon. XPS and MEIS analyses indicate that oxidation of yttrium on bare silicon results in a fully oxidized film with a significant fraction of Y–O–Si bonding. The mixed Y–O–Si structure results from the relatively rapid reaction between Y and the Si substrate to form yttrium silicide, followed by oxidation. The effect of various silicon pretreatments, including in situ oxidation and nitridation, on bulk and interface film composition are also examined. Transmission electron microscopy (TEM) of 40 Å thick films indicates that the yttrium silicate films are amorphous with uniform contrast throughout the layer. MEIS shows evidence for a graded metal concentration in the dielectric near the silicon interface, with uniform oxygen concentration (consistent with full oxidation) throughout the film. Angle resolved XPS (ARXPS) shows no significant signal related to Si+4, as would be expected from a substantial SiO2 interface layer. Capacitance–voltage analysis demonstrates that a ∼10 Å equivalent oxide thickness can be achieved. The effects of ultra-thin silicon oxide, nitrided-oxide and nitrided silicon interfaces on silicon consumption during the oxidation of yttrium are investigated. When yttrium is deposited on a thin (∼10 Å) SiO2 film and oxidized, a yttrium silicate film is formed with bonding and composition similar to films formed on bare silicon. However, when the interface is a thin nitride, the silicon consumption rate is significantly reduced, and the resulting film composition is closer to Y2O3. The consumption of the silicon substrate by metal is shown to occur during oxidation and during vacuum annealing of yttrium on silicon. The relatively rapid formation of metal–silicon bonds suggests that metal–silicon structures may also be important reactive intermediates in silicon/dielectric interface formation reactions during chemical vapor deposition. In addition to thermodynamic stability, understanding the relative rates of elementary reaction steps in film formation is critical to control composition and structure at the dielectric/Si interface. DA - 2001/9/3/ PY - 2001/9/3/ DO - 10.1016/S0169-4332(01)00373-7 VL - 181 IS - 1-2 SP - 78-93 SN - 0169-4332 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000171063300009&KeyUID=WOS:000171063300009 KW - X-ray photoelectron spectroscopy KW - transmission electron microscopy KW - capacitance-voltage curve ER - TY - JOUR TI - Cryogenic mechanical alloying as an alternative strategy for the recycling of tires AU - Smith, AP AU - Ade, H AU - Koch, CC AU - Spontak, RJ T2 - POLYMER AB - Cryogenic mechanical alloying (CMA) is investigated as a viable strategy by which to produce highly dispersed blends composed of thermoplastics and tire, thereby providing a potentially new route by which to recycle discarded tires. Morphological characterization of these blends by near-edge X-ray absorption fine structure (NEXAFS) microscopy demonstrates that, upon CMA, ground tire is highly dispersed within poly(methyl methacrylate) (PMMA) and poly(ethylene terephthalate) (PET) matrices at sub-micron size scales. Incorpo-ration of polyisoprene (PI) homopolymer into the blends to improve dispersion efficacy is also examined. Neither PI nor the tire is found to interact chemically with PMMA or PET under the milling conditions employed here. DA - 2001/4// PY - 2001/4// DO - 10.1016/S0032-3861(00)00804-1 VL - 42 IS - 9 SP - 4453-4457 SN - 0032-3861 KW - polymer recycling KW - cryogenic mechanical alloying KW - polymer blends ER - TY - JOUR TI - Anomalous phase inversion in polymer blends prepared by cryogenic mechanical alloying AU - Smith, AP AU - Ade, H AU - Smith, SD AU - Koch, CC AU - Spontak, RJ T2 - MACROMOLECULES AB - ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTAnomalous Phase Inversion in Polymer Blends Prepared by Cryogenic Mechanical AlloyingArchie P. Smith, Harald Ade, Steven D. Smith, Carl C. Koch, and Richard J. SpontakView Author Information Departments of Materials Science and Engineering, Physics, and Chemical Engineering, North Carolina State University, Raleigh, North Carolina 27695; and Corporate Research Division, The Procter and Gamble Company, Cincinnati, Ohio 45239 Cite this: Macromolecules 2001, 34, 6, 1536–1538Publication Date (Web):February 16, 2001Publication History Received5 July 2000Published online16 February 2001Published inissue 1 March 2001https://doi.org/10.1021/ma001151pCopyright © 2001 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views242Altmetric-Citations27LEARN 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. 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Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (288 KB) Get e-AlertsSUBJECTS:Organic compounds,Polymer morphology,Polymers,Viscosity,X-ray absorption near edge spectroscopy Get e-Alerts DA - 2001/3/13/ PY - 2001/3/13/ DO - 10.1021/ma001151p VL - 34 IS - 6 SP - 1536-1538 SN - 1520-5835 ER - TY - JOUR TI - Angle-dependent reflectometry as a technique for fast assessment of highly oriented diamond film quality AU - Wolter, SD AU - Schlesser, R AU - Okuzumi, F AU - Prater, JT AU - Sitar, Z T2 - DIAMOND AND RELATED MATERIALS AB - An expedient technique for assessing the quality of highly oriented diamond films is described. This analysis is based on light reflection from the {111} faces of oriented diamond octahedra as a function of azimuthal sample orientation. Significant light reflection was detected at 90° rotation intervals and the full-width-at-half-maximum of these periodic peaks was determined to be adequate for gauging the upper limit of crystal misorientation. In addition, a two-dimensional surface mapping of the distribution of highly oriented diamond across the sample was determined by analyzing reflectivity properties at equally spaced spots on the surface. DA - 2001/11// PY - 2001/11// DO - 10.1016/S0925-9635(01)00487-3 VL - 10 IS - 11 SP - 2092-2095 SN - 0925-9635 KW - heteroepitaxy KW - characterization KW - diamond films KW - orientation ER - TY - JOUR TI - A new approach to characterize crystallinity by observing the mobility of plasma treated polymer surfaces AU - Hyun, J T2 - POLYMER AB - We describe in this paper a novel method to characterize crystallinity by observing the difference in chain mobility of oxygen plasma treated polymer surfaces, and further compare the crystallinity with the values obtained by X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). We modified polymer surfaces with an inductively coupled plasma system to introduce polar functional groups. The immobility parameters of plasma modified surfaces were obtained by measuring contact angles as a function of storage time in air. Due to highly restricted chain mobility in the crystalline region, the crystallinity can be estimated by the fraction of immobile polar groups remaining after chain reorientation. DA - 2001/7// PY - 2001/7// DO - 10.1016/S0032-3861(01)00116-1 VL - 42 IS - 15 SP - 6473-6477 SN - 0032-3861 KW - surface KW - crystallinity KW - immobility ER - TY - JOUR TI - Transition from thermally grown gate dielectrics to deposited gate dielectrics for advanced silicon devices: A classification scheme based on bond ionicity AU - Lucovsky, G T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A AB - This article discusses the bonding chemistry of alternative high-k gate dielectrics that have been considered for advanced complementary metal–oxide–semiconductor devices. The replacement of SiO2 by alternative gate dielectrics requires a transition from a thermally deposited native oxide to a deposited gate dielectric. A classification scheme based on bond ionicity separates alternative gate dielectric materials into three groups that are differentiated by their amorphous morphology and electronic structure and properties. This scheme establishes trends between bond ionicity and (i) the average bonding coordination of the constituent atoms, (ii) the thermal stability against chemical phase separation and/or crystallization, and (iii) the dielectric constant. It also provides a framework for the evaluation of different criteria that have been proposed for optimization of alternative high-k metal and transition metal oxides, and their alloys with SiO2 and Al2O3. Based on technology targets for device and wafer performance and reliability, there is as yet no ideal replacement for SiO2 that increases capacitance while at the same time maintaining low levels of interfacial defects. DA - 2001/// PY - 2001/// DO - 10.1116/1.1379317 VL - 19 IS - 4 SP - 1553-1561 SN - 1520-8559 ER - TY - JOUR TI - Structure and properties of novel functional diamond-like carbon coatings produced by laser ablation AU - Wei, Q AU - Sankar, J AU - Narayan, J T2 - SURFACE & COATINGS TECHNOLOGY AB - Diamond-like carbon (DLC) mainly consists of sp3 bonded carbon atoms. It can have properties that rival those of crystalline diamond. Its beneficial properties stem from the continuous rigid random networks of sp3 carbon atoms, and the properties can essentially be tailored by the sp3/sp2 ratio. DLC coatings or thin films can be prepared by pulsed laser ablation (PLA), filtered cathodic vacuum arc (FCVA) deposition and mass selected ion beam (MSIB) deposition. In the past decade, tremendous progress has been made in experimental and theoretical investigations of hydrogen-free DLC. Experimental and commercial applications in microelectronics, micro-tribology, biomedical technologies, etc., have been demonstrated. Potential applications include sensors, flat panel displays (field emitters), photodiode, etc. In this paper, we report comprehensively the past and recent efforts in the research of functional diamond-like carbon coatings prepared by pulsed laser ablation in our group. In order to alleviate the internal compressive stress problem associated with high quality DLC coatings, we have adopted a novel and simple target design. The films were characterized by Raman spectroscopy, transmission electron microscopy, IR range optical measurements, tribological measurement, etc. DA - 2001/// PY - 2001/// DO - 10.1016/S0257-8972(01)01394-9 VL - 146 IS - 2001 Sep-Oct SP - 250-257 SN - 0257-8972 KW - diamond-like carbon KW - pulsed laser deposition KW - functional materials ER - TY - JOUR TI - Spatial distribution of carbon species in laser ablation of graphite target AU - Ikegami, T AU - Ishibashi, S AU - Yamagata, Y AU - Ebihara, K AU - Thareja, RK AU - Narayan, J T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A AB - We report on the temporal evolution and spatial distribution of C2 and C3 molecules produced by KrF laser ablation of a graphite target using laser induced fluorescence imaging and optical emission spectroscopy. Spatial density profiles of C2 were measured using two-dimensional fluorescence in various pressures of different ambient (vacuum, nitrogen, oxygen, hydrogen, helium, and argon) gases at various ablation laser fluences and ablation area. A large yield of C2 is observed in the central part of the plume and near the target surface and its density and distribution was affected by the laser fluence and ambient gas. Fluorescent C3 was studied in Ar gas and the yield of C3 is enhanced at higher gas pressure and longer delay times after ablation. DA - 2001/// PY - 2001/// DO - 10.1116/1.1381403 VL - 19 IS - 4 SP - 1304-1307 SN - 1520-8559 ER - TY - JOUR TI - Self-assembled AlInGaN quaternary superlattice structures AU - El-Masry, NA AU - Behbehani, MK AU - LeBoeuf, SF AU - Aumer, ME AU - Roberts, JC AU - Bedair, SM T2 - APPLIED PHYSICS LETTERS AB - When an AlInGaN quaternary alloy is grown by metalorganic chemical-vapor deposition under certain growth conditions, a self-assembled superlattice structure is obtained. The superlattice structure is made of quaternary layers with different AIN and InN compositions. Transmission electron microscopy data show that the superlattice periodicity is regular with an individual layer thickness that depends on the growth conditions. Secondary ion mass spectrometry measurements show that the layers’ composition alternate between high-AIN and InN content and low-AlN and-InN content, while the in-plane lattice constant remains constant for both layers. A model is presented as a preliminary effort to explain these results. DA - 2001/9/10/ PY - 2001/9/10/ DO - 10.1063/1.1400763 VL - 79 IS - 11 SP - 1616-1618 SN - 0003-6951 ER - TY - JOUR TI - Seeding effect on micro- and domain structure of sol-gel-derived PZT thin films AU - Kholkin, AL AU - Gruverman, A AU - Wu, A AU - Avdeev, M AU - Vilarinho, PM AU - Salvado, IMM AU - Baptista, JL T2 - MATERIALS LETTERS AB - Abstract Current trend to miniaturization requires precise control of micro- and domain structure of ferroelectric materials at the nanoscale level. This is essential for future applications of ferroelectric thin films in non-volatile memories, microactuators and pyroelectric arrays. In this work, the seeding effect on the nanoscale properties of ferroelectric Pb(Zr,Ti)O 3 (PZT) thin films is investigated using scanning force microscopy (SFM) capable of simultaneously resolving topographic and domain features on the surface of the films. It is shown that the addition of 5 mol% seeds (fine PZT powder) into the sol–gel precursor solution completely modifies the film's microstructure leading to the improved morphology of the grains, reduced roughness and smaller microporosity. At the same time, significant imprint and instability of the written domain pattern is reduced due to the smaller influence of the bottom electrode interface. DA - 2001/9// PY - 2001/9// DO - 10.1016/S0167-577X(01)00228-2 VL - 50 IS - 4 SP - 219-224 SN - 1873-4979 KW - SFM KW - sol-gel KW - PZT (Pb(Zr,Ti)O-3) films KW - ferroelectric domains ER - TY - JOUR TI - Review of pendeo-epitaxial growth and characterization of thin films of GaN and AlGaN alloys on 6H-SiC(0001) and Si(111) substrates AU - Davis, R. F. AU - Gehrke, T. AU - Linthicum, K. J. AU - Rajagopal, P. AU - Roskowski, A. M. AU - Zheleva, T. AU - Preble, E. A. AU - Zorman, C. A. AU - Mehregany, M. AU - Schwarz, U. AU - Schuck, J. AU - Grober, R. T2 - MRS Internet Journal of Nitride Semiconductor Research DA - 2001/// PY - 2001/// VL - 6 IS - 14 SP - 1-16 ER - TY - JOUR TI - Platinum-containing hyper-cross-linked polystyrene as a modifier-free selective catalyst for L-sorbose oxidation AU - Sidorov, SN AU - Volkov, , IV AU - Davankov, VA AU - Tsyurupa, MP AU - Valetsky, PM AU - Bronstein, LM AU - Karlinsey, R AU - Zwanziger, JW AU - Matveeva, VG AU - Sulman, EM AU - Lakina, NV AU - Wilder, EA AU - Spontak, RJ T2 - JOURNAL OF THE AMERICAN CHEMICAL SOCIETY AB - Impregnation of hyper-cross-linked polystyrene (HPS) with tetrahydrofuran (THF) or methanol (ML) solutions containing platinic acid results in the formation of Pt(II) complexes within the nanocavities of HPS. Subsequent reduction of the complexes by H2 yields stable Pt nanoparticles with a mean diameter of 1.3 nm in THF and 1.4 nm in ML. The highest selectivity (98% at 100% conversion) measured during the catalytic oxidation of L-sorbose in water is obtained with the HPS-Pt-THF complex prior to H2 reduction. During an induction period of about 100 min, L-sorbose conversion is negligible while catalytic species develop in situ. The structure of the catalyst isolated after the induction period is analyzed by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Electron micrographs reveal a broad distribution of Pt nanoparticles, 71% of which measure less than or equal to 2.0 nm in diameter. These nanoparticles are most likely responsible for the high catalytic activity and selectivity observed. The formation of nanoparticles measuring up to 5.9 nm in diameter is attributed to the facilitated intercavity transport and aggregation of smaller nanoparticles in swollen HPS. The catalytic properties of these novel Pt nanoparticles are highly robust, remaining stable even after 15 repeated uses. DA - 2001/10/31/ PY - 2001/10/31/ DO - 10.1021/ja0107834 VL - 123 IS - 43 SP - 10502-10510 SN - 0002-7863 ER - TY - JOUR TI - Physical and electrical properties of noncrystalline Al2O3 prepared by remote plasma enhanced chemical vapor deposition AU - Johnson, RS AU - Lucovsky, G AU - Baumvol, I T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A AB - Noncrystalline Al2O3 dielectric films have been synthesized by remote plasma enhanced chemical vapor deposition (RPECVD) and deposited on (i) H-terminated Si(100) and (ii) on SiO2 prepared by remote plasma assisted oxidation and RPECVD on Si(100) substrates using organometallic source gases injected downstream from a He/O2 plasma. Chemical composition and morphology of the Al2O3 films and their interfaces have been studied by Auger electron spectroscopy (AES), Fourier transform infrared spectroscopy, nuclear resonance profiling (NRP), and x-ray diffraction (XRD). Previous studies in which Al2O3 was deposited by thermal CVD, rapid thermal CVD, (RTCVD), direct PECVD, and physical vapor deposition generally resulted in relatively thick SiO2 or Al-silicate interfacial layers which impact adversely on the highest attainable capacitance. In line AES and NRP indicate the as-deposited RPECVD films are fully oxidized on deposition, and their interfaces can be chemically abrupt with Si oxide or Al silicate interfacial layers that are no more than 0.6 to 0.8 nm thick. However, these relatively abrupt interfaces do not ensure good device performance. Electrical measurements indicate negative fixed charge on the order of 1012 charges/cm2. The fixed charge resides at the Al2O3 interface, and can be moved away from the silicon substrate by deposition of a thin, ∼1–2 nm, intermediate layer of RPECVD SiO2. DA - 2001/// PY - 2001/// DO - 10.1116/1.1379316 VL - 19 IS - 4 SP - 1353-1360 SN - 1520-8559 ER - TY - JOUR TI - O-18 study of the oxidation of reactively sputtered Ti1-xAlxN barrier AU - Hugon, MC AU - Varniere, F AU - Letendu, F AU - Agius, B AU - Vickridge, L AU - Kingon, AI T2 - JOURNAL OF MATERIALS RESEARCH DA - 2001/9// PY - 2001/9// DO - 10.1557/JMR.2001.0356 VL - 16 IS - 9 SP - 2591-2599 SN - 0884-2914 ER - TY - JOUR TI - Nitrogen incorporation in ultrathin gate dielectrics: A comparison of He/N2O and He/N-2 remote plasma processes AU - Khandelwal, A AU - Smith, BC AU - Lamb, HH T2 - JOURNAL OF APPLIED PHYSICS AB - Ultrathin Si oxynitride films grown by low-temperature remote plasma processing were examined by on-line Auger electron spectroscopy and angle-resolved x-ray photoelectron spectroscopy to determine the concentration, spatial distribution, and chemical bonding of nitrogen. The films were grown at 300 °C on Si(100) substrates using two radio-frequency remote plasma processes: (i) He/N2O remote plasma-assisted oxidation (RPAO) and (ii) two-step remote plasma oxidation/nitridation. A 5 min He/N2O RPAO process produces a 2.5 nm oxynitride film incorporating approximately 1 monolayer of nitrogen at the Si–SiO2 interface. The interfacial nitrogen is bonded in a N–Si3 configuration, as in silicon nitride (Si3N4). By comparison, a 90 s He/N2 remote plasma exposure of a 1 nm oxide (grown by 10 s He/O2 RPAO) consumes substrate Si atoms creating a 1 nm subcutaneous Si3N4 layer. The nitrogen areal density obtained via the two-step process depends on the initial oxide thickness and the He/N2 remote plasma exposure time. Moreover, as the oxide thickness is increased (by increasing the He/O2 remote plasma exposure), the nitrogen distribution shifts away from the Si–SiO2 interface and into the oxide. More nitrogen with a tighter distribution is incorporated using He versus Ar dilution. Insight into the remote plasma chemistry was provided by optical emission spectroscopy. Strong N2 first positive and second positive emission bands were observed for He/N2O and He/N2 remote plasmas indicating the presence of N2 metastables and ground-state N atoms. DA - 2001/9/15/ PY - 2001/9/15/ DO - 10.1063/1.1397286 VL - 90 IS - 6 SP - 3100-3108 SN - 0021-8979 ER - TY - JOUR TI - Near-edge X-ray absorption fine structure (NEXAFS) microscopy of a polycarbonate/poly (acrylonitrile/butadiene/styrene) blend AU - Sloop, CC AU - Ade, H AU - Fornes, RE AU - Gilbert, RD AU - Smith, AP T2 - JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS AB - Journal of Polymer Science Part B: Polymer PhysicsVolume 39, Issue 5 p. 531-535 Rapid Communication Near-edge X-ray absorption fine structure (NEXAFS) microscopy of a polycarbonate/poly(acrylonitrile/butadiene/styrene) blend C. C. Sloop, Corresponding Author C. C. Sloop [email protected] North Carolina State University, Raleigh, North Carolina 27695-8209North Carolina State University, Raleigh, North Carolina 27695-8209Search for more papers by this authorH. Ade, H. Ade Physics Department, North Carolina State University, Raleigh, North Carolina 27695-8209Search for more papers by this authorR. E. Fornes, R. E. Fornes Physics Department, North Carolina State University, Raleigh, North Carolina 27695-8209Search for more papers by this authorR. D. Gilbert, R. D. Gilbert Fiber and Polymer Science Program, North Carolina State University, Raleigh, North Carolina 27695-8209Search for more papers by this authorA. P. Smith, A. P. Smith North Carolina State University, Raleigh, North Carolina 27695-8209Search for more papers by this author C. C. Sloop, Corresponding Author C. C. Sloop [email protected] North Carolina State University, Raleigh, North Carolina 27695-8209North Carolina State University, Raleigh, North Carolina 27695-8209Search for more papers by this authorH. Ade, H. Ade Physics Department, North Carolina State University, Raleigh, North Carolina 27695-8209Search for more papers by this authorR. E. Fornes, R. E. Fornes Physics Department, North Carolina State University, Raleigh, North Carolina 27695-8209Search for more papers by this authorR. D. Gilbert, R. D. Gilbert Fiber and Polymer Science Program, North Carolina State University, Raleigh, North Carolina 27695-8209Search for more papers by this authorA. P. Smith, A. P. Smith North Carolina State University, Raleigh, North Carolina 27695-8209Search for more papers by this author First published: 23 January 2001 https://doi.org/10.1002/1099-0488(20010301)39:5<531::AID-POLB1026>3.0.CO;2-QCitations: 7Read the full textAboutPDF 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 onEmailFacebookTwitterLinkedInRedditWechat REFERENCES AND NOTES 1 Stöhr, J. NEXAFS Spectroscopy; Springer-Verlag: Berlin, 1992. 10.1007/978-3-662-02853-7 Google Scholar 2 Ade, H.; Urquhart, S. In Chemical Applications of Synchrotron Radiation; T. K. 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At Data Nucl Data Tables 1993, 54, 181. 10.1006/adnd.1993.1013 CASWeb of Science®Google Scholar Citing Literature Volume39, Issue51 March 2001Pages 531-535 ReferencesRelatedInformation DA - 2001/3/1/ PY - 2001/3/1/ DO - 10.1002/1099-0488(20010301)39:5<531::AID-POLB1026>3.0.CO;2-Q VL - 39 IS - 5 SP - 531-535 SN - 1099-0488 KW - polycarbonate/acrylonitrile-butadiene-styrene (ABS) blends KW - near-edge X-ray absorption fine structure (NEXAFS) microscopy KW - reprocessing ER - TY - JOUR TI - Minority-carrier diffusion length in a GaN-based light-emitting diode AU - Gonzalez, JC AU - Bunker, KL AU - Russell, PE T2 - APPLIED PHYSICS LETTERS AB - Minority-carrier diffusion lengths of electrons and holes were measured in a GaN-based light-emitting diode using the electron-beam-induced current technique in the line-scan configuration. A theoretical model with an extended generation source and a nonzero surface recombination velocity was used to accurately extract the diffusion length of the p- and n-type layers. A minority-carrier diffusion length of Ln=(80±6) nm for electrons in the p-type GaN layer, Lp=(70±4) nm for holes in the n-type GaN:Si,Zn active layer, and Ln=(55±4) nm for electrons in the p-type Al0.1Ga0.9N layer were determined. The results from this model are compared with two simpler and widely used theoretical models. DA - 2001/9/3/ PY - 2001/9/3/ DO - 10.1063/1.1400075 VL - 79 IS - 10 SP - 1567-1569 SN - 0003-6951 ER - TY - PAT TI - Methods of raising reflow temperature of glass alloys by thermal treatment in steam, and microelectronic structures formed thereby AU - Croswell, R. T. AU - Reisman, A. AU - Simpson, D. L. AU - Temple, D. AU - Williams, C. K. C2 - 2001/// DA - 2001/// PY - 2001/// ER - TY - PAT TI - Methods of forming a plurality of semiconductor layers using spaced trench arrays AU - Gehrke, T. AU - Linthicum, K. J. AU - Davis, R. F. C2 - 2001/// DA - 2001/// PY - 2001/// ER - TY - PAT TI - Methods of fabricating gallium nitride semiconductor layers by lateral growth from sidewalls into trenches, and gallium nitride semiconductor structures fabricated thereby AU - Zheleva, T. AU - Thomson, D. B. AU - Smith, S. A. AU - Linthicum, K. J. AU - Gehrke, T. AU - Davis, R. F. C2 - 2001/// DA - 2001/// PY - 2001/// ER - TY - PAT TI - Methods of fabricating gallium nitride microelectronic layers on silicon layers and gallium nitride microelectronic structures formed thereby AU - Linthicum, K. J. AU - Gehrke, T. AU - Davis, R. F. AU - Thomson, D. B. AU - Tracy, K. M. C2 - 2001/// DA - 2001/// PY - 2001/// ER - TY - JOUR TI - Metalorganic chemical vapor deposition Pb(Zr,Ti)O-3 and selected lower electrode structures as a pathway to integrated piezoelectric microelectromechanical systems AU - Chen, IS AU - Roeder, JF AU - Kim, DJ AU - Maria, JP AU - Kingon, AI T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B AB - The actuation mechanism is an important aspect of many micromachined devices. Electrostatic actuation has been the prevailing actuation method due to its relative ease in implementation using conventional silicon microfabrication techniques. Other mechanisms are becoming more accessible to micromachine designs as new materials are introduced into the microfabrication process. Recent progress in nonvolatile memory has led to successful incorporation of Pb(Zr,Ti)O3 (PZT) thin films into microelectronic devices. The present work expands on this area and investigates PZT thin films and electrode/barrier combinations for applications in micromachined devices. Incorporation of PZT thin films into silicon micromachined devices requires electrode systems and deposition techniques that are compatible with silicon microfabrication. In this study, Ir/IrOx and Ir/(Ti,Al)N lower electrode systems were developed to suppress diffusion of reactive species (e.g., Pb) into silicon-based microelectromechanical system devices and to enhance PZT film adhesion. Piezoelectric PZT thin films from 0.3 to 1 μm thick were prepared on silicon wafers with these electrode structures by metalorganic chemical vapor deposition. Hysteresis loops of longitudinal piezoelectric coefficient (d33) were measured by dual-beam interferometry and used to characterize piezoelectric activity in these films. The effective d33 exhibited an apparent dependence on film thickness. d33 values up to 70 pm/V were obtained for 1 μm films, while thinner films exhibited lower d33 values between 54 and 60 pm/V. The dielectric loss (tan δ) was below 2% for most films irrespective of their thickness. DA - 2001/// PY - 2001/// DO - 10.1116/1.1401747 VL - 19 IS - 5 SP - 1833-1840 SN - 1071-1023 ER - TY - JOUR TI - Mechanical properties of nanocrystalline and epitaxial TiN films on (100) silicon AU - Wang, H AU - Sharma, A AU - Kvit, A AU - Wei, Q AU - Zhang, X AU - Koch, CC AU - Narayan, J T2 - JOURNAL OF MATERIALS RESEARCH DA - 2001/9// PY - 2001/9// DO - 10.1557/JMR.2001.0373 VL - 16 IS - 9 SP - 2733-2738 SN - 2044-5326 ER - TY - JOUR TI - Magnetic properties of self-assembled nanoscale La2/3Ca1/3MnO3 particles in an alumina matrix AU - Katiyar, P AU - Kumar, D AU - Nath, TK AU - Kvit, AV AU - Narayan, J AU - Chattopadhyay, S AU - Gilmore, WM AU - Coleman, S AU - Lee, CB AU - Sankar, J AU - Singh, RK T2 - APPLIED PHYSICS LETTERS AB - We have investigated the processing and properties of La2/3Ca1/3MnO3 self-assembled nanodots formed in a nonmagnetic alumina matrix, which were produced by a pulsed-laser deposition process. The size of the nanodots was found to be in the range of 10–15 nm using high-resolution transmission electron microcopy. The average interlayer separation between two dots has been found to be 2–5 nm, which is sufficient to decouple the magnetic grains. The decoupling of the grains is supported by the zero-field-cooled and field-cooled magnetization (M) data. The coercivity of the La2/3Ca1/3MnO3 nanodots has been measured using magnetization measurements as a function of field (H) at different temperatures above and below the blocking temperature of the samples. The coercivity is found to vary from 600 Oe at 10 K to 400 and 200 Oe at 20 and 50 K, respectively. Above the blocking temperature, the sample is found to transform to a superparamagnetic magnetic state, resulting in the disappearance of any hysteresis in the M–H loops. DA - 2001/8/27/ PY - 2001/8/27/ DO - 10.1063/1.1399001 VL - 79 IS - 9 SP - 1327-1329 SN - 0003-6951 ER - TY - JOUR TI - Lateral epitaxy and dislocation density reduction in selectively grown GaN structures AU - Zheleva, TS AU - Nam, OH AU - Ashmawi, WM AU - Griffin, JD AU - Davis, RF T2 - JOURNAL OF CRYSTAL GROWTH AB - The results of a comparative study of the defect microstructures at different regions in epitaxial, monocrystalline GaN structures grown selectively within windows in and laterally over SiO2 masks deposited on GaN/AlN/6H–SiC heterostructures are presented. The defects in the GaN grown within the SiO2 windows were predominantly threading dislocations of mostly mixed character with Burgers vector b=1/3〈112̄3〉 and edge dislocations with b=1/3〈112̄0〉 with a density range of 109–1010 cm−2, as determined using transmission electron microscopy (TEM). The regions of lateral epitaxial overgrowth (LEO-GaN) contained short dislocation segments parallel to the interfacial planes, which were usually aligned parallel or nearly parallel to the 〈11̄00〉 or 〈112̄0〉 directions and with densities of ⩽106 cm−2. Specific morphologies exhibited by the LEO-GaN were determined to be associated with the mechanism of stress relaxation. Finite element analysis of these complex heterostructures showed that the accommodation of the mismatches in the coefficients of thermal expansion among the different phases in the heterostructures was manifest in the formation of the curved surfaces observed in cross-sectional TEM. DA - 2001/2// PY - 2001/2// DO - 10.1016/S0022-0248(00)00832-0 VL - 222 IS - 4 SP - 706-718 SN - 1873-5002 KW - epitaxy KW - selective growth KW - lateral epitaxial overgrowth KW - gallium nitride KW - pendeo-epitaxy KW - defects KW - transmission electron microscopy ER - TY - JOUR TI - Ion implantation into gallium nitride AU - Ronning, C AU - Carlson, EP AU - Davis, RF T2 - PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS AB - This comprehensive review is concerned with studies regarding ion implanted gallium nitride (GaN) and focuses on the improvements made in recent years. It is divided into three sections: (i) structural properties, (ii) optical properties and (iii) electrical properties. The first section includes X-ray diffraction (XRD), transmission electron microscopy (TEM), secondary ion mass spectroscopy (SIMS), Rutherford Backscattering (RBS), emission channeling (EC) and perturbed γγ-angular correlation (PAC) measurements on GaN implanted with different ions and doses at different temperatures as a function of annealing temperature. The structural changes upon implantation and the respective recovery upon annealing will be discussed. Several standard and new annealing procedures will be presented and discussed. The second section describes mainly photoluminescence (PL) studies, however, the results will be discussed with respect to Raman and ellipsometry studies performed by other groups. We will show that the PL-signal is very sensitive to the processes occurring during implantation and annealing. The results of Hall and C–V measurements on implanted GaN are presented in Section 3. We show and discuss the difficulties in achieving electrical activation. However, optical and electrical properties are both a result of the structural changes upon implantation and annealing. Each section will be critically discussed with respect to the existing literature, and the main conclusions are drawn from the interplay of the results obtained from the different techniques used/reviewed. DA - 2001/9// PY - 2001/9// DO - 10.1016/S0370-1573(00)00142-3 VL - 351 IS - 5 SP - 349-385 SN - 1873-6270 KW - ion implantation KW - gallium nitride KW - structural properties KW - optical properties KW - dopants ER - TY - JOUR TI - Heavy-ion-induced breakdown in ultra-thin gate oxides and high-k dielectrics AU - Massengill, LW AU - Choi, BK AU - Fleetwood, DM AU - Schrimpf, RD AU - Galloway, KF AU - Shaneyfelt, MR AU - Meisenheimer, TL AU - Dodd, PE AU - Schwank, , JR AU - Lee, YM AU - Johnson, RS AU - Lucovsky, G T2 - IEEE TRANSACTIONS ON NUCLEAR SCIENCE AB - Presents experimental results on single-event-induced breakdown in sub-5-nm plasma-enhanced SiO/sub 2/, nitrided SiO/sub 2/, Al/sub 2/O/sub 3/, HfO/sub 2/, and Zr/sub 0.4/Si/sub 1.6/O/sub 4/ dielectrics typical of current and future-generation commercial gate oxides. These advanced oxides are found to be quite resistant to ion-induced breakdown. Radiation-induced soft breakdown was observed in some films with 342 MeV Au (LET=80 MeV/mg/cm/sup 2/) but not 340 MeV I (LET=60 MeV/mg/cm/sup 2/). The critical voltage to hard breakdown was found to scale with the square root of the physical oxide thickness, not with the energy stored on the gate capacitance. Alternative dielectrics with equivalent oxide thickness substantially below their physical thickness were found to exhibit significantly higher voltage to hard breakdown than SiO/sub 2/ counterparts. All of the samples reached ion-induced hard breakdown at applied voltages well above typical operating power-supply voltages; these findings bode well for the use of advanced commercial integrated circuits in space systems. DA - 2001/12// PY - 2001/12// DO - 10.1109/23.983149 VL - 48 IS - 6 SP - 1904-1912 SN - 1558-1578 KW - dielectric breakdown KW - dielectric reliability KW - scaling KW - single-event radiation effects ER - TY - JOUR TI - Gas permeation properties of poly(1,1 '-dihydroperfluorooctyl acrylate), poly(1,1 '-dihydroperfluorooetyl methacrylate), and poly(styrene)-b-poly(1,1 '-dihydroperfluorooctyl acrylate) block copolymers AU - Arnold, ME AU - Nagai, K AU - Freeman, BD AU - Spontak, RJ AU - Betts, DE AU - DeSimone, JM AU - Pinnau, I T2 - MACROMOLECULES AB - The permeabilities of rubbery poly(1,1‘-dihydroperfluorooctyl acrylate) (PFOA), glassy poly(1,1‘-dihydroperfluorooctyl methacrylate) (PFOMA), and poly(styrene)-b-poly(1,1‘-dihydroperfluorooctyl acrylate) (PS-b-PFOA) diblock copolymers to N2, O2, H2, CH4, C2H6, and CO2 at 446 kPa and to C3H8 at 308 kPa are reported as a function of temperature. In general, PFOMA has lower fractional free volume, smaller gas permeability coefficients, and larger activation energies of permeation than PFOA, consistent with the more restricted long-range segmental mobility of PFOMA. The PS-b-PFOA copolymers exhibit complex microphase-separated morphologies, and their gas permeability coefficients are intermediate between those of glassy PS and rubbery PFOA, decreasing in magnitude with increasing PS content. DA - 2001/7/31/ PY - 2001/7/31/ DO - 10.1021/ma010355i VL - 34 IS - 16 SP - 5611-5619 SN - 0024-9297 ER - TY - JOUR TI - Exploratory study into the effects of an electric field and of high current density electropulsing on the plastic deformation of TiAl AU - Yang, D AU - Conrad, H T2 - INTERMETALLICS AB - The effects of an external electric field (2 kV/cm) and of high density electric current pulsing (2×104 A/cm2, 60 μs duration and 20 pulses per second) on the stress–strain curve of TiAl in compression at 600 °C were determined. The field gave a significant reduction in yield stress followed by a moderate increase in strain hardening. In contrast, electropulsing increased the yield stress and gave a smaller increase in strain hardening. The effects of the electric field and of electropulsing developed during the early stages of plastic deformation (ε<∼2%) and were retained upon subsequent straining without the field or current. Moreover, initial straining (ε<∼2%) without an electric field gave a microstructure which did not respond to the electric field applied during subsequent straining. The results suggest that the electric field and the electropulsing had an influence on the microstructure which developed at small strain through an effect on one or more of the following: (a) stacking fault energy, (b) twinning energy or (c) antiphase boundary energy. DA - 2001/// PY - 2001/// DO - 10.1016/S0966-9795(01)00094-2 VL - 9 IS - 10-11 SP - 943-947 SN - 0966-9795 KW - titanium aluminides, based on Ti3Al KW - brittleness and ductility KW - work-hardening KW - yield stress KW - mechanical properties at high temperatures ER - TY - JOUR TI - Electron traps at interfaces between Si(100) and noncrystalline Al2O3, Ta2O5, and (Ta2O5)(x)(Al2O3)(1-x) alloys AU - Johnson, R. S. AU - Hong, J. G. AU - Lucovsky, G. T2 - Journal of Vacuum Science & Technology. B, Microelectronics and Nanometer Structures DA - 2001/// PY - 2001/// VL - 19 IS - 4 SP - 1606-1610 ER - TY - JOUR TI - Chemical and physical limits on the performance of metal silicate high-k gate dielectrics AU - Lucovsky, G AU - Rayner, GB AU - Johnson, RS T2 - MICROELECTRONICS RELIABILITY AB - This research identifies four significant limitations on the performance of high-k alternative gate dielectrics that derive from inherent relationships between (i) chemical bonding and physical properties, and (ii) device operation. These include interfacial band offset energies, thermal stability against chemical phase separation, coordination dependent dielectric constants, and interfacial fixed charge. Then these are applied to transition metal silicate alloys, e.g., (ZrO2)x(SiO2)1−x. The paper also includes results for other high-k oxides, Al2O3 and Ta2O5, and their alloys that relate to the issues addressed in this paper, and in particular help to put the results on the silicate alloys into a better perspective. This portion of the paper provides additional perspective with regard to the differences in the chemical and physical limitations of elemental oxides and binary oxide alloys. DA - 2001/7// PY - 2001/7// DO - 10.1016/S0026-2714(01)00046-4 VL - 41 IS - 7 SP - 937-945 SN - 0026-2714 ER - TY - JOUR TI - Characteristics of metalorganic remote plasma chemical vapor deposited Al2O3 gate stacks on SiC metal-oxide-semiconductor devices AU - Lazar, HR AU - Misra, V AU - Johnson, RS AU - Lucovsky, G T2 - APPLIED PHYSICS LETTERS AB - Metalorganic remote plasma chemical vapor deposited SiO2/Al2O3 stacks were deposited on 6H p-type silicon SiC to fabricate a high-k gate stack SiC metal–oxide–semiconductor capacitors. Capacitance–voltage (C–V) and current–voltage (I–V) measurements were performed. C–V characteristics showed excellent properties at room and higher temperatures. Samples exhibited a slight negative flatband shift from which the net oxide charge (Qox) was calculated. Low leakage currents were observed even at high temperatures. I–V characteristics of Al2O3 were superior to those observed on AlN and SiO2 dielectrics on SiC. DA - 2001/8/13/ PY - 2001/8/13/ DO - 10.1063/1.1392973 VL - 79 IS - 7 SP - 973-975 SN - 1077-3118 ER - TY - JOUR TI - Band gap structure and electron emission property of chemical-vapor-deposited diamond films AU - Liu, JJ AU - Chiu, DYT AU - Morton, DC AU - Kang, DH AU - Zhirnov, , VV AU - Hren, JJ AU - Cuomo, JJ T2 - SOLID-STATE ELECTRONICS AB - The structures of the band gap and defect states of chemical-vapor-deposited diamond films were investigated by photoluminescence spectroscopy, covering wavelength from visible to vacuum ultraviolet (VUV). Band gaps ranging from 5.5 to 3.2 eV were measured for natural, polycrystalline, and amorphous diamond films. Low voltage field emissions were obtained from wide band gap films with band gap states distributed close to the conduction band and extended deeply into the band gap. Amorphous diamond film with a narrower band gap could not provide low field emission. DA - 2001/6// PY - 2001/6// DO - 10.1016/S0038-1101(00)00210-0 VL - 45 IS - 6 SP - 915-919 SN - 0038-1101 ER - TY - JOUR TI - Time-resolved spectroscopy of strained GaN/AlN/6H-SiC heterostructures grown by metalorganic chemical vapor deposition AU - Pozina, G AU - Edwards, NV AU - Bergman, JP AU - Paskova, T AU - Monemar, B AU - Bremser, MD AU - Davis, RF T2 - APPLIED PHYSICS LETTERS AB - Temperature-dependent time-resolved photoluminescence measurements were performed on GaN film/AlN buffer/6H–SiC substrate heterostructures grown by metalorganic chemical vapor deposition. The overlying GaN layers were under tension, as estimated from the free A exciton (FEA) position. The recombination lifetimes were determined for the FEA and for the neutral-donor-bound exciton (D0X). We observed that the recombination lifetime for the FEA has the same value of 40–50 ps in all the layers, whereas the recombination time for the D0X varies for different samples. We observed that the recombination lifetimes for D0X have a clear dependence on the position of FEA, i.e., the recombination lifetime increases with decreasing strain in the layers. We discuss the results in term of the hole states involved in the donor-bound exciton recombination. DA - 2001/2/19/ PY - 2001/2/19/ DO - 10.1063/1.1350421 VL - 78 IS - 8 SP - 1062-1064 SN - 0003-6951 ER - TY - JOUR TI - Theoretical study of indium compounds of interest for organometallic chemical vapor deposition AU - Cardelino, BH AU - Moore, CE AU - Cardelino, CA AU - Frazier, DO AU - Bachmann, KJ T2 - JOURNAL OF PHYSICAL CHEMISTRY A AB - The structural, electronic, and thermochemical properties of indium compounds which are of interest in halide transport and organometallic chemical vapor deposition processes have been studied by ab initio and statistical thermodynamic methods. The compounds reported include: indium halides and hydrides (InF, InCl, InCl3, InH, InH2, InH3); indium clusters (In2, In3); methylindium, dimethylindium, and their hydrogen derivatives [In(CH3), In(CH3)H, In(CH3)H2, In(CH3)2, In(CH3)2H]; dimethylindium dimer [In2(CH3)4] and trimethylindium [In(CH3)3]; dehydrogenated methyl-, dimethyl-, and trimethylindium [In(CH3)2CH2, In(CH3)CH2, In(CH2)]; trimethylindium adducts with ammonia, trimethylamine and hydrazine [(CH3)3In:NH3, (CH3)3In:N(CH3)3, (CH3)3In:N(H2)N(H2)]; dimethylamino-indium and methylimino-indium [In(CH3)2(NH2), In(CH3)(NH)]; indium nitride and indium nitride dimer (InN, In2N2); indium phosphide, -arsenide, and -antimonide (InP, InAs, InSb). The predicted electronic properties are based on density functional theory calculations; the calculated thermodynamic properties are reported following the format of the JANAF (Joint Army, Navy, NASA, Air Force) Tables. Equilibrium compositions at two temperatures (298 and 1000K) have been analyzed for groups of competing simultaneous reactions. DA - 2001/2/8/ PY - 2001/2/8/ DO - 10.1021/jp0013558 VL - 105 IS - 5 SP - 849-868 SN - 1520-5215 ER - TY - JOUR TI - Quantitative analysis of a-Si1-xCx : H thin films by vibrational spectroscopy and nuclear methods AU - Gracin, D AU - Bogdanovic, I AU - Borjanovic, V AU - Jaksic, M AU - Pastuovic, Z AU - Dutta, JM AU - Vlahovic, B AU - Nemanich, RJ T2 - VACUUM AB - Thin amorphous hydrogenated silicon–carbon films, a-Si1−xCx : H were deposited by magnetron sputtering on glass and mono-crystalline substrates with carbon content from x=0.2 to 1, wide variation of hydrogen concentration and different degrees of structural ordering. The obtained films were investigated by Fourier transform infra-red (FTIR) spectroscopy, Raman spectroscopy, Rutherford backscattering (RBS) and elastic recoil detection analysis (ERDA). The results of the quantitative analyses obtained by the above-mentioned techniques were compared. It has been concluded that the applied vibrational methods can be used quantitatively which enables estimation of the degree of chemical ordering in the analysed samples. DA - 2001/5/14/ PY - 2001/5/14/ DO - 10.1016/S0042-207X(01)00134-8 VL - 61 IS - 2-4 SP - 303-308 SN - 0042-207X KW - quantitative analysis KW - amorphous silicon carbide KW - FTIR KW - Raman KW - RBS KW - ERDA ER - TY - JOUR TI - Optimization of scanning transmission X-ray microscopy for the identification and quantitation of reinforcing particles in polyurethanes AU - Hitchcock, AP AU - Koprinarov, I AU - Tyliszczak, T AU - Rightor, EG AU - Mitchell, GE AU - Dineen, MT AU - Hayes, F AU - Lidy, W AU - Priester, RD AU - Urquhart, SG AU - Smith, AP AU - Ade, H T2 - ULTRAMICROSCOPY AB - The morphology, size distributions, spatial distributions, and quantitative chemical compositions of co-polymer polyol-reinforcing particles in a polyurethane have been investigated with scanning transmission X-ray microscopy (STXM). A detailed discussion of microscope operating procedures is presented and ways to avoid potential artifacts are discussed. Images at selected photon energies in the C 1s, N 1s and O 1s regions allow unambiguous identification of styrene-acrylonitrile-based (SAN) copolymer and polyisocyanate polyaddition product-based (PIPA) reinforcing particles down to particle sizes at the limit of the spatial resolution (50 nm). Quantitative analysis of the chemical composition of individual reinforcing particles is achieved by fitting C 1s spectra to linear combinations of reference spectra. Regression analyses of sequences of images recorded through the chemically sensitive ranges of the C 1s, N 1s and O 1s spectra are used to generate quantitative compositional maps, which provide a fast and effective means of investigating compositional distributions over a large number of reinforcing particles. The size distribution of all particles determined by STXM is shown to be similar to that determined by TEM. The size distributions of each type of reinforcing particle, which differ considerably, were obtained by analysis of STXM images at chemically selective energies. DA - 2001/6// PY - 2001/6// DO - 10.1016/S0304-3991(00)00113-3 VL - 88 IS - 1 SP - 33-49 SN - 1879-2723 KW - X-ray microscopy KW - polymers KW - quantitative chemical mapping KW - particle size distributions ER - TY - JOUR TI - On the similarity of macromolecular responses to high-energy processes: mechanical milling vs. irradiation AU - Smith, AP AU - Spontak, RJ AU - Ade, H T2 - POLYMER DEGRADATION AND STABILITY AB - Recent efforts to blend and compatibilize intrinsically immiscible polymers in the solid state by high-energy methods have shown that macromolecules may undergo scission, crosslinking or amorphization, depending on the chemical nature of the repeat unit, the processing temperature and the initial degree of polymer crystallinity. Identical process-induced molecular and structural modifications have been previously observed in polymers exposed to large doses of electron and γ radiation, suggesting that the responses of polymers to high-energy processes may be mechanistically similar. In this work, we explore a variety of similarities between mechanically-milled and irradiated polymers in terms of molecular characteristics, process temperature and polymer crystallinity, and we demonstrate that these similarities provide predictive guidance for the selection of polymers to be subjected to solid-state processing. DA - 2001/// PY - 2001/// DO - 10.1016/S0141-3910(01)00055-6 VL - 72 IS - 3 SP - 519-524 SN - 0141-3910 KW - mechanical milling KW - solid-state processing KW - chemical structure KW - radiation damage ER - TY - JOUR TI - Frequency and duty cycle dependence on the pulsed bias-enhanced nucleation of highly oriented diamond on (100) silicon AU - Wolter, SD AU - Okuzumi, F AU - Prater, JT AU - Sitar, Z T2 - PHYSICA STATUS SOLIDI A-APPLIED RESEARCH AB - Pulsed bias-enhanced nucleation of highly oriented diamond on (100) silicon is reported. A square waveform substrate bias was implemented in this investigation employing a pulse ON bias voltage of —250 V and a pulse OFF bias voltage of 0 V. An evaluation of the pulse ON fractions of 0.17 and 0.50 revealed a duty cycle dependence on the bias time required for forming a diamond film as well as the highly oriented diamond percentage. Oriented crystallite percentages of nearly 50% and 20% were observed for the 0.17 and 0.50 pulse ON fractions, respectively. Pulse biasing from 10 to 100 Hz (again implementing a square waveform bias and a pulse ON fraction of 0.17) did not influence the process of forming the epitaxial diamond. Throughout this frequency range the onset of diamond film formation was approximately 60 min and a nominal highly oriented diamond percentage of 50% was observed. DA - 2001/7/23/ PY - 2001/7/23/ DO - 10.1002/1521-396x(200108)186:2<331::aid-pssa331>3.0.co;2-1 VL - 186 IS - 2 SP - 331-337 SN - 0031-8965 ER - TY - JOUR TI - Formation of cobalt disilicide films on (root 3 x root 3)6H-SiC(0001) AU - Platow, W AU - Wood, DK AU - Tracy, KM AU - Burnette, JE AU - Nemanich, RJ AU - Sayers, DE T2 - PHYSICAL REVIEW B AB - This paper presents a detailed study of thin Co films grown directly, sequentially, and by codeposition with Si on the $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})\ensuremath{-}R30\ifmmode^\circ\else\textdegree\fi{}$ surface of $6H\ensuremath{-}\mathrm{SiC}(0001).$ The structure, chemistry, and morphology of the films were determined using x-ray absorption fine structure, x-ray photoelectron spectroscopy, Auger electron spectroscopy, and atomic force microscopy. For directly deposited Co films (1--8 nm) graphite layers form on top of the film surface during annealing, whereas Co stays mainly unreacted over a temperature range of 300--1000 \ifmmode^\circ\else\textdegree\fi{}C. The formation of ${\mathrm{CoSi}}_{2}$ is achieved by sequential and codeposition of Co and Si. Films annealed at 550 \ifmmode^\circ\else\textdegree\fi{}C are polycrystalline and further annealing to 650 \ifmmode^\circ\else\textdegree\fi{}C causes no C segregation, but there is islanding of the films. Attempts to improve film morphology and homogeneity including applying a template method and varying growth temperature are also reported. DA - 2001/3/15/ PY - 2001/3/15/ DO - 10.1103/physrevb.63.115312 VL - 63 IS - 11 SP - SN - 1550-235X ER - TY - JOUR TI - Elimination of endpoint-discontinuity artifacts in the analysis of spectra in reciprocal space AU - Yoo, SD AU - Aspnes, DE T2 - JOURNAL OF APPLIED PHYSICS AB - Reciprocal-space analysis offers several advantages for determining critical point parameters in optical and other spectra, for example the separation of baseline effects, information, and noise in low-, medium-, and high-index Fourier coefficients, respectively. However, endpoint-discontinuity artifacts can obscure much of the information when segments are isolated for analysis. We developed a procedure for eliminating these artifacts and recovering buried information by minimizing in the white-noise region the mean-square deviation between the Fourier coefficients of the data and those of low-order polynomials, then subtracting the resulting coefficients from the data over the entire range. We find that spectral analysis is optimized if no false data are used, i.e., when the number of points transformed equals the number of actual data points in the segment. Using fractional differentiation we develop a simple derivation of the variation of the reciprocal-space coefficients with index n for Lorentzian and Gaussian line shapes in direct space. More generally, we show that the definition of critical point energies in terms of phase coherence of the Fourier coefficients allows these energies to be determined for a broad class of line shapes even if the direct-space line shapes themselves are not known. Limitations for undersampled or highly broadened spectra are discussed, along with extensions to two- or higher-dimensional arrays of data. DA - 2001/6/15/ PY - 2001/6/15/ DO - 10.1063/1.1368391 VL - 89 IS - 12 SP - 8183-8192 SN - 0021-8979 ER - TY - JOUR TI - Use of metal-oxide-semiconductor capacitors to detect interactions of Hf and Zr gate electrodes with SiO2 and ZrO2 AU - Misra, V. AU - Heuss, G. P. AU - Zhong, H. T2 - Applied Physics Letters AB - Metal–oxide–semiconductor capacitors were used to study the interaction of Hf and Zr gate electrodes on SiO2, ZrSixOy, and ZrO2. A large reduction in the SiO2 equivalent oxide thickness accompanied by an increase in the leakage current was observed with Hf and Zr electrodes when subjected to anneal temperatures as low as 400 °C. The reduction in electrical thickness as observed from the capacitance–voltage measurements was attributed to the combination of (a) physical thinning of the SiO2 and (b) formation of a high-K layer. A severe instability of Zr and Hf electrodes was also observed on ZrSixOy and ZrO2 dielectrics. This behavior of Zr and Hf gates was attributed to high negative enthalpy of oxide formation and high oxygen solubility resulting in the reduction of the gate dielectric and subsequent oxygen diffusion to the gate electrode. DA - 2001/// PY - 2001/// DO - 10.1063/1.1380240 VL - 78 IS - 26 SP - 4166-4168 ER - TY - JOUR TI - Two field-emission states of single-walled carbon nanotubes AU - Collazo, R AU - Schlesser, R AU - Sitar, Z T2 - APPLIED PHYSICS LETTERS AB - Two field-emission states of single-walled carbon nanotubes have been identified according to their respective emission current levels. The state yielding increased emission current has been attributed to the presence of adsorbates on the nanotubes. It was realized that, by application of high electric fields inducing large emission currents, a transition between the two states could be induced. For the high current state, field-emitted electrons originated from states located 1 eV below the Fermi level, as was determined by field-emission energy distribution measurements. This suggested that adsorbates introduced a resonant state on the surface that enhanced the tunneling probability of the electrons. These states are removed when the nanotubes are cleaned by application of a large electric field, thus, decreasing the field-emitted current. DA - 2001/4/2/ PY - 2001/4/2/ DO - 10.1063/1.1361089 VL - 78 IS - 14 SP - 2058-2060 SN - 0003-6951 ER - TY - JOUR TI - The ternary system Fe-Nd-C AU - Grieb, B. AU - Henig, E. T. AU - Reinsch, B. AU - Petzow, G. AU - Buschow, K. H. J. AU - De Mooij, D. B. AU - Stadelmaier, H. H. T2 - Zeitschrift fur MetallkundeAmerican Journal of Physiology DA - 2001/// PY - 2001/// VL - 92 IS - 2 SP - 172-178 ER - TY - JOUR TI - Phonons in III-V nitrides: Confined phonons and interface phonons AU - Dutta, M AU - Alexson, D AU - Bergman, L AU - Nemanich, RJ AU - Dupuis, R AU - Kim, KW AU - Komirenko, S AU - Stroscio, M T2 - PHYSICA E AB - Phonons in III–V nitrides are examined experimentally for dimensionally confined systems and for alloys of InGaN with a view towards understanding the phonon modes of these systems. Results are compared with the predictions of Loudon's model for uniaxial semiconductors. The modes of the InGaN system are compared with those of the AlGaN ternary alloy. The first Raman measurements of interface phonons in binary GaN–AlN superlattices are presented. DA - 2001/10// PY - 2001/10// DO - 10.1016/S1386-9477(01)00217-X VL - 11 IS - 2-3 SP - 277-280 SN - 1386-9477 KW - confined optical phonons KW - Raman scattering KW - wurtzites KW - nitrides ER - TY - JOUR TI - Pendeo-epitaxial growth and characterization of thin films of gallium nitride and related materials on SiC(0001) and si(111) substrates AU - Davis, R. F. AU - Gehrke, T. AU - Linthicum, K. J. AU - Zheleva, T. S. AU - Rajagopal, P. AU - Zorman, C. A. AU - Mehregany, M. T2 - Zeitschrift fur MetallkundeAmerican Journal of Physiology DA - 2001/// PY - 2001/// VL - 92 IS - 2 SP - 163-166 ER - TY - JOUR TI - Oxygen transport during annealing of Pb(Zr,Ti)O-3 thin films in O-2 gas and its effect on their conductivity AU - Ayguavives, F AU - Agius, B AU - Ea-Kim, B AU - Vickridge, I T2 - JOURNAL OF MATERIALS RESEARCH DA - 2001/10// PY - 2001/10// DO - 10.1557/JMR.2001.0412 VL - 16 IS - 10 SP - 3005-3008 SN - 2044-5326 ER - TY - JOUR TI - Electrosintering of iron powder compacts AU - Fahmy, Y. AU - Conrad, H. T2 - Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science DA - 2001/// PY - 2001/// DO - 10.1007/s11661-001-0097-7 VL - 32 IS - 3A SP - 811-819 ER - TY - JOUR TI - Effect of hydrogen on true leakage current characteristics of (Pb,La)(Zr,Ti)O-3 thin-film capacitors with Pt- or Ir-based top electrodes AU - Yoon, SG AU - Wicaksana, D AU - Kim, DJ AU - Kim, SH AU - Kingon, AI T2 - JOURNAL OF MATERIALS RESEARCH DA - 2001/4// PY - 2001/4// DO - 10.1557/JMR.2001.0163 VL - 16 IS - 4 SP - 1185-1189 SN - 2044-5326 ER - TY - JOUR TI - Dynamic rheological behavior of DBS-induced poly(propylene glycol) physical gels AU - Mercurio, DJ AU - Khan, SA AU - Spontak, RJ T2 - RHEOLOGICA ACTA DA - 2001/1// PY - 2001/1// DO - 10.1007/s003970000119 VL - 40 IS - 1 SP - 30-38 SN - 1435-1528 KW - physical gels KW - dibenzylidene sorbitol KW - network recovery KW - nanofibrils KW - organogels ER - TY - JOUR TI - Ultraviolet raman study of A(1)(LO) and E-2 phonons in InxGa1-xN alloys AU - Alexson, D AU - Bergman, L AU - Nemanich, RJ AU - Dutta, M AU - Stroscio, MA AU - Parker, CA AU - Bedair, SM AU - El-Masry, NA AU - Adar, F T2 - JOURNAL OF APPLIED PHYSICS AB - We report on ultraviolet Raman spectroscopy of InxGa1−xN thin films grown on sapphire by metal-organic chemical vapor deposition. The A1(LO) and E2 phonon mode behavior was investigated over a large compositional range (0&lt;x&lt;0.50). Compelling evidence is presented for one-mode behavior for the A1(LO) phonon, and data suggestive of two-mode behavior are presented for the E2 phonon. DA - 2001/1/1/ PY - 2001/1/1/ DO - 10.1063/1.1330760 VL - 89 IS - 1 SP - 798-800 SN - 0021-8979 ER - TY - JOUR TI - Time-dependent Si etch behavior and its effect on oxide/Si selectivity in CF4+D-2 electron cyclotron resonance plasma etching AU - Min, K AU - Lamb, HH AU - Hauser, , JR T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B AB - Transient poly-Si etching behavior in CF4+D2 electron cyclotron resonance plasmas containing different D2 proportions was investigated. Higher D2 proportions resulted in lower atomic F and higher CF2 concentration in the plasma, as evidenced by optical emission spectroscopy (OES), and in greater oxide-to-Si etch selectivity. A high initial poly-Si etch rate that declined very rapidly to a finite-steady-state value was observed for plasma etching under conditions giving low (3:1) oxide-to-Si etch selectivity. In contrast, a lower initial etch rate that declined to approximately zero over a longer (∼45 s) period was observed for poly-Si etching under plasma conditions giving (∼15:1) selectivity. In the latter case, Si consumption during overetching would be significantly underestimated if calculated on the basis of the conventional 60 s selectivity ration. X-ray photoelectron spectroscopy analysis indicated that a thick, more F-deficient fluorocarbon film was deposited on Si under the high-selectivity etching conditions. Real-time SiF4 and atomic F signals, which were measured during SiO2 etching using OES and mass spectroscopy, respectively, evidenced significantly different end-point trends for the high- and low-selectivity etching conditions. These trends are interpreted in light of the transient etching behavior observed for poly-Si under equivalent plasma conditions. DA - 2001/// PY - 2001/// DO - 10.1116/1.1371318 VL - 19 IS - 3 SP - 695-700 SN - 1071-1023 ER - TY - JOUR TI - Self-healing on OPA self-assembled monolayers AU - Neves, BRA AU - Salmon, ME AU - Troughton, EB AU - Russell, PE T2 - NANOTECHNOLOGY AB - Controlled scratches on octadecylphosphonic acid self-assembled monolayers were made using atomic force microscopy tips as indenters. Scratch morphological evolution was followed as a function of time, at room temperature, for samples prepared by drip coating and crystal melting methods. Self-healing, ranging from partial to complete, was observed on drip coated samples. However, no substantial healing was observed on crystal melted samples. Such different behaviour is discussed in terms of the scratching mechanism on both sample types. DA - 2001/9// PY - 2001/9// DO - 10.1088/0957-4484/12/3/315 VL - 12 IS - 3 SP - 285-289 SN - 0957-4484 ER - TY - JOUR TI - Raman spectroscopic characterization of diamond films grown in a low-pressure flat flame AU - Wolter, SD AU - Prater, JT AU - Sitar, Z T2 - JOURNAL OF CRYSTAL GROWTH AB - Diamond films produced in the low-pressure flat flame have been examined using Raman spectroscopy. The effect of the oxy-acetylene gas mixture (R=O2/C2H2 gas ratio of 0.95 to 1.06) and substrate temperature (650–850°C) on the form of the non-diamond carbon as well as the diamond phase purity and crystallinity are reported. An assessment of the diamond crystallinity was achieved by inspection of the full-width-at-half-maximum (FWHM) of the Raman line observed at 1332±0.5 cm−1 representing sp3-bonded carbon. This analysis revealed a FWHM as low as ∼4.3 cm−1 for the optimum growth conditions of an R=1.05 and substrate temperatures of 650–750°C. The broad non-diamond carbon component in the 1350 cm−1 to 1650 cm−1 range was deconvoluted into three distinct Gaussian peaks at 1355±1.5 cm−1, 1470±7.5 cm−1, and 1550±4.0 cm−1. These peaks remained in the same relative proportion regardless of the processing conditions, and the total area of the non-diamond peaks was found to correspond linearly with the background luminescence. A relative comparison of the diamond and non-diamond carbon was used to qualitatively estimate the diamond film phase purity. DA - 2001/6// PY - 2001/6// DO - 10.1016/S0022-0248(01)01274-X VL - 226 IS - 1 SP - 88-94 SN - 1873-5002 KW - characterization KW - low-pressure flat flame growth KW - diamond ER - TY - JOUR TI - Predicted structure and electronic properties of individual carbon nanocones and nanostructures assembled from nanocones AU - Shenderova, OA AU - Lawson, BL AU - Areshkin, D AU - Brenner, DW T2 - NANOTECHNOLOGY AB - Calculations using an analytic potential show that carbon nanocones can exhibit conventional cone shapes or can form concentric wave-like metastable structures, depending on the nanocone radius. Single nanocones can be assembled into extended two-dimensional structures arranged in a self-similar fashion with fivefold symmetry as system size is increased. Calculations of the electronic properties of nanocones indicate that a pentagon in the centre of a cone is the most probable spot for emitting tunnelling electrons in the presence of an external field. This implies that nanocone assemblies, if practically accessible, could be used as highly localized electron sources for templating at scales below more traditional lithographies. DA - 2001/9// PY - 2001/9// DO - 10.1088/0957-4484/12/3/302 VL - 12 IS - 3 SP - 191-197 SN - 1361-6528 ER - TY - JOUR TI - Polarization charges and polarization-induced barriers in AlxGa1-xN/GaN and InyGa1-yN/GaN heterostructures AU - Jia, L AU - Yu, ET AU - Keogh, D AU - Asbeck, PM AU - Miraglia, P AU - Roskowski, A AU - Davis, RF T2 - APPLIED PHYSICS LETTERS AB - Polarization charges are measured and the formation of large electrostatic barriers arising primarily as a consequence of the presence of polarization-induced charge densities is deduced from capacitance–voltage analysis of n-type AlxGa1−xN/GaN and InyGa1−yN/GaN heterostructures. In structures consisting of 5–10 nm AlxGa1−xN or InyGa1−yN surrounded by n-GaN, capacitance–voltage profiling studies combined with elementary electrostatic analysis yield experimental estimates of polarization charge densities, which are compared with values expected based on the combined effects of spontaneous and piezoelectric polarization. These results imply the existence of electrostatic barriers that are due primarily to the large polarization charge densities at each heterojunction interface and the resulting potential difference maintained across the thin AlxGa1−xN or InyGa1−yN layers. The electrostatic barriers formed in these structures are large in comparison to the heterojunction conduction-band offsets, demonstrating the utility of polarization-based engineering of electrostatic barriers in nitride semiconductor heterostructures. DA - 2001/10/29/ PY - 2001/10/29/ DO - 10.1063/1.1412594 VL - 79 IS - 18 SP - 2916-2918 SN - 0003-6951 ER - TY - PAT TI - Pendeoepitaxial gallium nitride semiconductor layers on silicon carbide substrates AU - Linthicum, K. J. AU - Gehrke, T. AU - Thomson, D. B. AU - Carlson, E. P. AU - Rajagopal, P. AU - Davis, R. F. C2 - 2001/// DA - 2001/// PY - 2001/// ER - TY - JOUR TI - Optical characterization of wide band gap amorphous semiconductors (a-Si : C : H): Effect of hydrogen dilution AU - Park, M AU - Teng, CW AU - Sakhrani, V AU - McLaurin, MB AU - Kolbas, RM AU - Sanwald, RC AU - Nemanich, RJ AU - Hren, JJ AU - Cuomo, JJ T2 - JOURNAL OF APPLIED PHYSICS AB - The effect of hydrogen dilution on the optical properties of a wide band gap amorphous semiconductor (a-Si:C:H) was investigated. The samples were prepared by glow discharge decomposition of tetramethylsilane and were characterized primarily by optical techniques: spectroscopic ellipsometry, Raman scattering, infrared absorption, spectrophotometry, and UV photoluminescence. The deposition rate decreased with hydrogen dilution, while the silicon to carbon ratio remained constant with the addition of hydrogen. The optical band gap of this material increased as the hydrogen flow rate increased. Infrared absorption studies show that the concentration of hydrogen which is bonded to carbon decreases systematically upon hydrogen dilution. Hydrogen dilution appears to reduce the size and concentration of sp2 bonded carbon clusters, possibly caused by the etching of sp2 clusters by atomic hydrogen. The result was also supported by the shift of the Raman G peak position to a lower wave number region. Room temperature photoluminescence in the visible spectrum was observed with UV excitation. DA - 2001/1/15/ PY - 2001/1/15/ DO - 10.1063/1.1332421 VL - 89 IS - 2 SP - 1130-1137 SN - 1089-7550 ER - TY - JOUR TI - Microstructure coarsening during static annealing of 60Sn4OPb solder joints: III intermetallic compound growth kinetics AU - Jung, K AU - Conrad, H T2 - JOURNAL OF ELECTRONIC MATERIALS DA - 2001/10// PY - 2001/10// DO - 10.1007/s11664-001-0116-x VL - 30 IS - 10 SP - 1308-1312 SN - 0361-5235 KW - intermetallic compound KW - CU3Sn KW - Cu6Sn5 KW - diffusion KW - activation energy ER - TY - JOUR TI - Microstructure coarsening during static annealing of 60Sn4OPb solder joints: II eutectic coarsening kinetics AU - Jung, K AU - Conrad, H T2 - JOURNAL OF ELECTRONIC MATERIALS DA - 2001/10// PY - 2001/10// DO - 10.1007/s11664-001-0115-y VL - 30 IS - 10 SP - 1303-1307 SN - 0361-5235 KW - phase coarsening kinetics KW - activation energy KW - grain boundary diffusion ER - TY - JOUR TI - Microstructure coarsening during static annealing of 60Sn4OPb solder joints: I stereology AU - Jung, K AU - Conrad, H T2 - JOURNAL OF ELECTRONIC MATERIALS DA - 2001/10// PY - 2001/10// DO - 10.1007/s11664-001-0114-z VL - 30 IS - 10 SP - 1294-1302 SN - 0361-5235 KW - solder joints KW - phase size distribution KW - positive skew KW - log-normal function KW - time invariant KW - shape factor ER - TY - JOUR TI - Investigation and control of MOVPE growth by combined spectroscopic ellipsometry and reflectance-difference spectroscopy AU - Ebert, M AU - Bell, KA AU - Flock, K AU - Aspnes, DE T2 - PHYSICA STATUS SOLIDI A-APPLIED RESEARCH AB - The detailed characterization of epitaxial growth by metal organic vapor phase epitaxy (MOVPE) and its closed-loop feedback control at the sample level require a combination of thin-film, near-surface, and surface-sensitive techniques to determine layer thicknesses and compositions, the composition of the most recently deposited material, and surface chemistry, respectively. These data can be obtained nondestructively by spectroscopic ellipsometry (SE) and reflectance-difference (-anisotropy) spectroscopy (RDS/RAS). We describe the first unified optical system, basically a rotating-polarizer ellipsometer (RPE) integrated within a modified commercial rotating-sample MOVPE reactor, that performs both SE and RDS simultaneously in a single optical path. We provide examples of its use, showing in particular that GaP can intermix with Si during the initial stages of heteroepitaxy, and demonstrating sample-driven closed-loop feedback control of epitaxy through the fully automatic deposition of an InxGa1—xP parabolic quantum well. These results illustrate capabilities of the presented configuration and its potential for future use. DA - 2001/3/15/ PY - 2001/3/15/ DO - 10.1002/1521-396x(200103)184:1<79::aid-pssa79>3.0.co;2-b VL - 184 IS - 1 SP - 79-87 SN - 0031-8965 ER - TY - JOUR TI - Imaging electron emission from diamond film surfaces: N-doped diamond vs. nanostructured diamond AU - Kock, FAM AU - Garguilo, JM AU - Nemanich, RJ T2 - DIAMOND AND RELATED MATERIALS AB - Abstract This study reports direct imaging of electron emission from two different classes of diamond containing films that were prepared by microwave plasma chemical vapor deposition. These are N-doped, and nanostructured diamond containing films. The electron emission is excited by UV light (photoemission) or by an applied field (field emission). The photo electron emission microscopy (PEEM) of the N-doped films exhibited uniform emission, and upon heating to ∼700°C, field electron emission microscopy (FEEM) of the films showed similar uniform emission. In contrast, FEEM of the nanostructured films showed high brightness, localized emission sites at room temperature. The results indicate different processes for electron emission from nanostructured and N-doped diamond films. DA - 2001/// PY - 2001/// DO - 10.1016/S0925-9635(01)00401-0 VL - 10 IS - 9-10 SP - 1714-1718 SN - 1879-0062 KW - electron emission KW - diamond KW - N-doped ER - TY - JOUR TI - Copper passivation of boron in Si1-xGex alloys and boron reactivation kinetics AU - Barthula, M. AU - Aboelfotoh, M. O. AU - Meyer, F. T2 - Microelectronic Engineering AB - Abstract Copper passivation of boron in SiGe layers has been investigated by the use of Schottky barrier structures prepared by the deposition of copper on boron-doped SiGe alloys at room temperature. The boron passivation occurs at room temperature after Cu deposition and diffusion in the alloy. The Cu diffusivity is enhanced by dislocations and retarded by increasing the Ge content and (or) the compressive strain. The mechanisms for passivation seem similar to those evidenced for pure silicon: the fast-diffusing interstitial Cu + passivates the boron acceptors by forming neutral B–Cu complexes. The reactivation of boron is partially obtained after annealing at 200°C while the Cu 3 Si 1− x Ge x phase is formed. The reaction kinetics are first order with an activation energy of 0.76 eV. DA - 2001/// PY - 2001/// DO - 10.1016/S0167-9317(00)00463-9 VL - 55 IS - 1-4 SP - 323-328 ER - TY - JOUR TI - Polarization retention in SrBi2Ta2O9 thin films investigated at nanoscale AU - Gruverman, A. AU - Tanaka, M. T2 - Journal of Applied Physics DA - 2001/// PY - 2001/// VL - 89 IS - 3 SP - 1836-1843 ER - TY - JOUR TI - Ordering of cylindrical microdomains in thin films of hybrid isotropic/liquid crystalline triblock copolymers AU - Figueiredo, P AU - Geppert, S AU - Brandsch, R AU - Bar, G AU - Thomann, R AU - Spontak, RJ AU - Gronski, W AU - Samlenski, R AU - Muller-Buschbaum, P T2 - MACROMOLECULES AB - We have investigated the roles of liquid crystallinity (LC) and substrate interactions on the ordering of isotropic cylindrical microdomains in thin films of two hybrid isotropic/LC triblock copolymers. Each copolymer consists of polystyrene (PS) end blocks and a side-chain LC midblock that exhibits either a nematic or smectic mesophase up to temperatures beyond the glass transition temperature (Tg) of PS. In thin films measuring on the same order as the lattice period, the orientation of the cylinders relative to the substrate is sensitive to the interactions of the mesogens at internal microdomain boundaries and external interfaces. Upon annealing such copolymer films at temperatures below the LC → isotropic transition but above the PS Tg on a neutral NaCl substrate, the PS cylinders within the nematic matrix adopt a long-range parallel orientation, whereas those within the smectic matrix lie perpendicular to the substrate and exhibit liquidlike order. After long annealing times, the cylinders residing near the film surface within the smectic matrix reorganize from perpendicular to parallel orientation due to surface tension at the film/air interface. On a polished Si substrate that promotes homeotropic mesogen anchoring, the perpendicular cylindrical orientation within the smectic mesophase remains stable. DA - 2001/1/16/ PY - 2001/1/16/ DO - 10.1021/ma0011441 VL - 34 IS - 2 SP - 171-180 SN - 0024-9297 ER - TY - JOUR TI - Microstructural changes due to heat-treatment of annealing and their effect on the creep behavior of self-reinforced silicon nitride ceramics AU - Wei, Q AU - Sankar, J AU - Narayan, J T2 - MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING AB - In order to understand the improvement of creep resistance by furnace and microwave annealing, we have investigated the effect of heat-treatment on the microstructural characteristics of the crept self-reinforced silicon nitride (Si3N4) ceramic GS44. X-ray diffraction was performed on the as-sintered and heat-treated samples to study the phase changes due to annealing treatment. Optical microscopy and scanning electron microscopy (SEM) were used to study the fracture surface and to identify the creep mechanism. High resolution and analytical transmission electron microscopy (TEM) were employed to analyze the microstructures of the crept samples with as-received and heat-treated conditions. It has been reported that both conventional furnace and microwave annealing enhance the creep resistance of the material, and microwave annealing had the most significant effect. Fractography showed that the microwave annealed samples exhibits least creep damage. Furnace annealing also reduces the creep damage, but the effect is far less as compared to microwave annealing. Scanning electron microscopy (SEM) analysis showed significant amount of multiple-junction cavitation in the creep-tested samples. TEM observations showed significant devitrification of the amorphous phases in the microwave annealed specimens, as verified by micro-diffraction studies of the junction phases. This is also confirmed by X-ray diffraction and high-resolution lattice image of the triple junction phases. The microstructural observations were combined with a recent model of the effect of amorphous residues in ceramics on the creep behavior to explain the improvement in the creep resistance due to annealing. DA - 2001/2/15/ PY - 2001/2/15/ DO - 10.1016/s0921-5093(00)01403-9 VL - 299 IS - 1-2 SP - 141-151 SN - 0921-5093 KW - silicon nitride KW - ceramics KW - microwave annealing KW - microstructures KW - creep ER - TY - JOUR TI - Lead zirconate titanate thin films on base-metal foils: an approach for embedded high-permittivity passive components AU - Maria, J.-P. AU - Cheek, K. AU - Streiffer, S. AU - Kim, S. H. AU - Dunn, G. AU - Kingon, A. T2 - Journal of the American Ceramic Society AB - An approach for embedding high‐permittivity dielectric thin films into glass epoxy laminate packages has been developed. Lead lanthanum zirconate titanate (Pb 0.85 La 0.15 (Zr 0.52 Ti 0.48 ) 0.96 O 3 , PLZT) thin films were prepared using chemical solution deposition on nickel‐coated copper foils that were 50 μm thick. Sputter‐deposited nickel top electrodes completed the all‐base‐metal capacitor stack. After high‐temperature nitrogen‐gas crystallization anneals, the PLZT composition showed no signs of reduction, whereas the base‐metal foils remained flexible. The capacitance density was 300–400 nF/cm 2 , and the loss tangent was 0.01–0.02 over a frequency range of 1–1000 kHz. These properties represent a potential improvement of 2–3 orders of magnitude over currently available embedded capacitor technologies for polymeric packages. DA - 2001/// PY - 2001/// DO - 10.1111/j.1151-2916.2001.tb01029.x VL - 84 IS - 10 SP - 2436-2438 ER - TY - JOUR TI - New frontiers: Self-assembly and nanoelectronics AU - Zhirnov, , VV AU - Herr, DJC T2 - COMPUTER AB - In the quest for new semiconductor materials and processes, researchers focus on self-assembly, a concept that draws from diverse disciplines like chemistry, biology, material science, and electrical engineering. The following areas are examined: information theory; thermodynamics, synergetics and self-assembly; ribosome based lithography; nanofabrication by self-assembly; molecular electronics; and smart matter. DA - 2001/1// PY - 2001/1// DO - 10.1109/2.895116 VL - 34 IS - 1 SP - 34-+ SN - 0018-9162 ER - TY - JOUR TI - Hydrogen Raman shifts in carbon nanotubes from molecular dynamics simulation AU - Frankland, SJV AU - Brenner, DW T2 - CHEMICAL PHYSICS LETTERS AB - Shifts in Raman peak position relative to the gas-phase vibrational frequency have been calculated for molecular hydrogen in individual single-shell carbon nanotubes and nanotube ropes using a semiclassical model. The calculations predict that isolated hydrogen molecules inside of nanotubes have a Raman frequency that increases with nanotube size for radii less than about 2 nm, while intercalated hydrogen frequencies are independent of nanotube size. The model indicates that shifts in Raman frequencies could be used experimentally to distinguish between hydrogen inside and intercalated between nanotubes. DA - 2001/2/2/ PY - 2001/2/2/ DO - 10.1016/s0009-2614(00)01454-8 VL - 334 IS - 1-3 SP - 18-23 SN - 0009-2614 ER - TY - JOUR TI - In situ cleaning of GaN/6H-SiC substrates in NH3 AU - McGinnis, AJ AU - Thomson, D AU - Davis, RF AU - Chen, E AU - Michel, A AU - Lamb, HH T2 - JOURNAL OF CRYSTAL GROWTH AB - Metalorganic chemical vapor deposition-grown GaN on 6H-SiC substrates were cleaned by annealing in an NH3 flux. Oxygen contamination was removed by thermal desorption, and carbon removal was facilitated by reaction with NH3. The GaN(0 0 0 1) surface after NH3 beam cleaning at 730°C was smooth with distinct atomic steps. The roughness (0.20 nm RMS) was only slightly greater than that of the untreated substrate (0.17 nm RMS). Carbon and oxygen concentrations were reduced to background levels (∼1 at%) by annealing in an NH3 flux at 800°C. The surface step structure was destroyed by annealing in an NH3 flux of 4×1015 cm−2 s−1 from a seeded supersonic beam; however, annealing in an NH3 flux of 7×1015 cm−2 s−1 from a leak valve inhibited surface roughening and produced a relatively smooth surface (0.28 nm RMS) with a 3×3 R30° reconstruction. We infer from the effects of annealing temperature and NH3 flux that the observed surface roughening is due to GaN decomposition. DA - 2001/1// PY - 2001/1// DO - 10.1016/s0022-0248(00)00947-7 VL - 222 IS - 3 SP - 452-458 SN - 0022-0248 KW - gallium nitride KW - surface preparation KW - ammonia KW - homoepitaxy ER - TY - JOUR TI - Metastable tetragonal zirconia formation and transformation in reactively sputter deposited zirconia coatings AU - Ji, Z AU - Haynes, JA AU - Ferber, MK AU - Rigsbee, JM T2 - SURFACE & COATINGS TECHNOLOGY AB - Zirconia coatings were produced by reactive d.c. magnetron sputter deposition using a system with multiple sputter sources and a biased substrate stage. Crystal structure and phase stability of the coatings were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Tetragonal zirconia with either a random orientation or a highly (111) preferred orientation was deposited when a substrate bias was applied, whereas coatings grown with no substrate bias had the equilibrium monoclinic structure. It was revealed that bias sputtering effectively decreased crystallite size in the as-deposited coatings, which resulted in room temperature stabilization of the metastable tetragonal phase. XRD analysis of annealed coatings showed that the volume fraction and stability of the tetragonal phase was strongly dependent on substrate bias and annealing temperature. DA - 2001/1/15/ PY - 2001/1/15/ DO - 10.1016/S0257-8972(00)00910-5 VL - 135 IS - 2-3 SP - 109-117 SN - 0257-8972 KW - coating KW - zirconia KW - magnetron sputter deposition KW - phase transformation ER - TY - JOUR TI - Effect of chamber pressure and atmosphere on the microstructure and nanomechanical properties of amorphous carbon films prepared by pulsed laser deposition AU - Wei, Q AU - Sankar, J AU - Sharma, AK AU - Yamagata, Y AU - Narayan, J T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS AB - We have investigated the effect of chamber pressure and atmosphere on the microstructure and nanomechanical properties of amorphous carbon thin films prepared by pulsed laser deposition. The amorphous carbon films were deposited in various atmospheres such as nitrogen and argon at different chamber pressures. We used Raman spectroscopy to study the bonding characteristics of the deposited amorphous carbon films. Atomic force microscopy and optical microscopy were utilized to observe the surface conditions and the microstructures of the deposited films. Nanoindentation measurements were carried out on various samples prepared under different conditions to study the effect of chamber pressure and atmosphere on the elastic modulus and nanohardness of the films. It was found that reduced vacuum leads to formation of amorphous carbon films with reduced elastic modulus and nanohardness. Amorphous carbon films prepared under higher chamber pressures exhibit an increased density of particulates and significantly roughened surface. The results were understood in combination with the optical emission and electrostatic measurements of the laser plasma plume. It was found that the presence of atmosphere decreases the leading edge ionic energies of the species in the laser plasma plume and increases the thermalization of the laser plasma due to an increased possibility of collision. DA - 2001/// PY - 2001/// DO - 10.1116/1.1322641 VL - 19 IS - 1 SP - 311-316 SN - 0734-2101 ER - TY - JOUR TI - Time-resolved photoluminescence in strained GaN layers AU - Pozina, G. AU - Edwards, N. V. AU - Bergman, J. P. AU - Monemar, B. AU - Bremser, M. D. AU - Davis, R. F. T2 - Physica Status Solidi. A, Applications and Materials Science DA - 2001/// PY - 2001/// VL - 183 IS - 1 SP - 151-155 ER - TY - JOUR TI - Thin film of aluminum oxide through pulsed laser deposition: a micro-Raman study AU - Misra, A AU - Bist, HD AU - Navati, MS AU - Thareja, RK AU - Narayan, J T2 - MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY AB - Successful use of micro-Raman spectroscopy to characterize the surface of the thin Al2O3 films deposited on Si(010) substrate through pulsed laser ablation is presented. The micro-Raman spectra have been recorded on several spots (sized ≈1 μm) over the length and the breadth of the films in a systematic fashion. The as-deposited films are inhomogeneous from spot-to-spot over the surface. The variation in characteristic properties of 521 cm−1 line of crystalline Si (c-Si) have been used to estimate the thickness of the Al2O3 films. The thickness of the films has been found to depend on the position of the substrate with respect to the plume boundaries produced by the laser pulse after hitting the Al target. The thickness also depends on the position of the spot on a film placed at a fixed distance from the target surface. The thickness profiling of the deposited films on the basis of micro-Raman spectroscopic investigations corroborates the theoretical prediction of the model of the plume formation and the formation of the shock-front region in the pulsed laser deposition technique. All the seven Raman active modes (2A1g+5Eg) observable in single crystals of sapphire (c-Al2O3) powder have been identified in the complex spectra obtained from deposited film surfaces under varying experimental conditions. The intensity variation of an isolated line (750 cm−1) of Al2O3 corroborates the deposition profiling obtained from c-Si line parameters. The most intense Raman lines in the micro-Raman spectra of the deposited films are two infrared active modes around 450 and 600 cm−1. The strong presence of these infrared active modes in the micro-Raman spectra suggests a highly distorted micro-crystalline structure of the films. The local micro-stress created by the micro-crystals on the Si-substrate is maximum near the stopping distance of the plume. Largest micro-crystal of Al2O3 are also seen over the spot near the stopping distance of the plume. DA - 2001/1/4/ PY - 2001/1/4/ DO - 10.1016/s0921-5107(00)00554-7 VL - 79 IS - 1 SP - 49-54 SN - 0921-5107 ER - TY - JOUR TI - Spectroscopic ellipsometry study of InGaAs alloy films grown on InP AU - Seong, G. Y. AU - Bang, C. Y. AU - Kim, Y. D. AU - Wang, J. AU - Aspnes, D. E. AU - Koo, B. H. AU - Yao, T. T2 - Journal of the Korean Physical Society DA - 2001/// PY - 2001/// VL - 39 IS - 2001 Dec SP - S389-392 ER - TY - JOUR TI - Growth of tetragonal zirconia coatings by reactive sputter deposition AU - Ji, ZQ AU - Rigsbee, JM T2 - JOURNAL OF THE AMERICAN CERAMIC SOCIETY AB - Zirconia coatings were produced by reactive dc magnetron sputter deposition, using a system with multiple sputter sources and a biased substrate stage. Tetragonal zirconia with either a random orientation or a highly (111) preferred orientation was formed by applying a substrate bias. Coating grown with no substrate bias had the equilibrium monoclinic structure. X‐ray diffraction and transmission electron microscopy analyses revealed that bias sputtering could effectively decrease crystalline size in the as‐deposited coating, which resulted in room‐temperature stabilization of the tetragonal phase. The fraction of tetragonal phase, the desired phase for transformation‐toughening behavior, was strongly dependent on the substrate bias and post‐deposition annealing temperature. DA - 2001/12// PY - 2001/12// DO - 10.1111/j.1151-2916.2001.tb01102.x VL - 84 IS - 12 SP - 2841-2844 SN - 0002-7820 ER - TY - JOUR TI - Dissociation reactions of hydrogen in remote plasma-enhanced chemical-vapor-deposition silicon nitride AU - Boehme, C AU - Lucovsky, G T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS AB - Dominant hydrogen dissociation reactions during annealing of hydrogenated amorphous-silicon nitride were determined by comparison of the bond density dynamics with various reaction models. The sample material was produced with remote plasma-enhanced chemical-vapor deposition, deposited at high-ammonia-to-silane flow ratios (ammonia rich). The heat treatment was performed with rapid thermal annealing at various annealing temperatures and times as well as samples containing different stoichiometries and isotopes (hydrogenated and deuterated). The experiments showed that hydrogen loss during annealing is mostly due to molecular hydrogen (H2) release as long as SiH bonds are contained in the film. After their exhaustion, an ammonia (NH3) producing reaction prevails at temperatures between 600 and 900 °C. DA - 2001/// PY - 2001/// DO - 10.1116/1.1398538 VL - 19 IS - 5 SP - 2622-2628 SN - 0734-2101 ER - TY - JOUR TI - Thermal expansion and elastic properties of InN AU - Wang, K AU - Reeber, RR T2 - APPLIED PHYSICS LETTERS AB - The thermal expansion coefficients of wurtzite structure InN are evaluated within the constraints of a basic model and predicted for an extended temperature range. Together with the elastic constants provided earlier, this information gives a basis for optimizing thin-film growth conditions and thereby reducing the residual stresses in group-III-nitride thin-film devices. DA - 2001/9/10/ PY - 2001/9/10/ DO - 10.1063/1.1400082 VL - 79 IS - 11 SP - 1602-1604 SN - 1077-3118 ER - TY - JOUR TI - Structural and magnetoresistance properties of La2/3Ca1/3MnO3 thin films on buffered silicon substrates AU - Kumar, D. AU - Chattopadhyay, S. AU - Gilmore, W. M. AU - Lee, C. B. AU - Sankar, J. AU - Kvit, A. AU - Sharma, A. K. AU - Narayan, Jagdish AU - Pietambaram, S. V. AU - Singh, R. K. AU - al. T2 - APPLIED PHYSICS LETTERS AB - We report an epitaxial growth of LCMO (La2/3Ca1/3MnO3) film on Si by using a highly conducting diffusion barrier layer of TiN. In order to achieve epitaxial growth of LCMO films, MgO, and SrTiO3 films were used as intermediate layers between LCMO and TiN layers. The results have indicated that the properties of LCMO films on Si substrates, deposited under an optimized condition, are on par with the properties of LCMO films on conventional oxide substrates such as LaAlO3 and SrTiO3 in terms of paramagnetic to ferromagnetic transition temperature, insulator to metal transition temperature, and magnetoresistance ratio. DA - 2001/2/19/ PY - 2001/2/19/ DO - 10.1063/1.1350603 VL - 78 IS - 8 SP - 1098-1100 SN - 0003-6951 ER - TY - JOUR TI - Space charge and the dependence of the flow stress of ceramics on an applied electric field AU - Conrad, H T2 - SCRIPTA MATERIALIA AB - Spark plasma sintering (SPS), also known as pulsed electric current sintering (PECS) or field-assisted sintering technique (FAST), belongs to a class of powder metallurgy techniques. In SPS, the sample is simultaneously subjected to a uniaxial pressure and electrical current in a vacuum or protective atmosphere. Although the fundamental principles of this procedure were first proposed over 50 years ago, SPS acquired major importance only within the last 20 years. Scholars come to realize that SPS technique enables control of the powder surface condition, atomic diffusion behavior, and phase stability and crystal growth behavior, as well as accelerating densification of hard-to-sinter materials. This review summarizes the latest research findings with respect to experimental procedures, densification behaviors, microstructural characteristics, and mechanical properties of various traditional and novel materials synthesized using SPS, mainly highlighting the heating mechanisms in SPS and the effects induced by multi-physical fields on materials. In addition, influences of operating parameters containing current, voltage, and uniaxial pressure on product characteristics are reviewed for a wide range of materialsincluding hard-to-sinter materials, carbon-containing materials, nanocrystalline materials, non-equilibrium materials, gradient materials, interconnect materials, complex shape materials, and advanced functional materials. DA - 2001/2/2/ PY - 2001/2/2/ DO - 10.1016/S1359-6462(00)00589-3 VL - 44 IS - 2 SP - 311-316 SN - 1359-6462 KW - space charge KW - electrochemical potential KW - vacancies KW - flow stress KW - electric field ER - TY - JOUR TI - Photon energy dependence of contrast in photoelectron emission microscopy of Si devices AU - Ballarotto, VW AU - Siegrist, K AU - Phaneuf, RJ AU - Williams, ED AU - Yang, WC AU - Nemanich, RJ T2 - APPLIED PHYSICS LETTERS AB - We investigate the variation in doping-induced contrast with photon energy in photoelectron emission microscopy images of Si pn devices using a free-electron laser as a tunable monochromatic light source. Photoyield is observed from p-doped regions of the devices for photon energies as low as 4.5 eV. Band tailing is the dominant effect contributing to the low energy photoyield from the heavily doped p regions. The low intensity tail from the n regions, however, may be from surface states. DA - 2001/5/28/ PY - 2001/5/28/ DO - 10.1063/1.1376151 VL - 78 IS - 22 SP - 3547-3549 SN - 0003-6951 ER - TY - JOUR TI - Perfectly-alternating linear (AB)(n) multiblock copolymers: Effect of molecular design on morphology and properties AU - Spontak, RJ AU - Smith, SD T2 - JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS AB - Abstract Perfectly‐alternating linear (AB) n multiblock copolymers consist of n AB block pairs covalently linked in an alternating sequence. Although these copolymers can microphase‐order in the same fashion as their lower‐order ( n = 1) diblock analogs, the 2( n − 1) biconformational midblocks comprising each copolymer molecule have a considerable impact on microstructural characteristics and bulk properties. We have applied transmission electron microscopy, differential scanning calorimetry (DSC), and extensional rheometry to examine and compare the morphologies and properties of two series of compositionally symmetric (lamellar) poly(styrene‐ b ‐isoprene) n (SI) n (1 ≤ n ≤ 4) multiblock copolymers. In one series, chain length was held constant allowing block mass ( M b ) to decrease with increasing n . In the second copolymer series, M b remained relatively invariant. Increasing n in these two series generally promoted reductions in both the lamellar period and upper (styrenic) glass‐transition temperature, but noticeable increases in tensile modulus and yield strength. These observed trends are more pronounced in the copolymer series with constant chain length due to the coupled relationship between n and M b . © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 947–955, 2001 DA - 2001/5/1/ PY - 2001/5/1/ DO - 10.1002/polb.1070 VL - 39 IS - 9 SP - 947-955 SN - 0887-6266 KW - block copolymer KW - polymer nanostructure KW - segmented copolymer KW - polymer network ER - TY - JOUR TI - Numerical studies of nonuniform deformation, stress state evolution, and subgrain formation in bicrystals in (110) channel die compression AU - Yu, PG AU - Havner, KS T2 - JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS AB - Abstract An elastoplastic numerical model for f.c.c. bicrystals in (110) channel die compression is investigated to a logarithmic strain of 10% and compared with the analytical rigid-plastic solution at the yield point. Three lattice orientations of an aluminum bicrystal are calculated between constraint directions [00 1 ] and [1 1 2 ] . It is found that the elastoplastic results for each of stress state, velocity field and lattice-rotation rate (indicating subgrain formation) pass very close to the analytical solution at 0.2% strain for two of the orientations. This is in spite of small tangential velocity discontinuities along characteristic directions of that solution which are not permitted in the numerical (finite element) modeling. The results are never as close in the third orientation, for which there are much greater tangential velocity discontinuities in the rigid-plastic model. It is suggested that the elastoplastic comparisons with the rigid-plastic model may provide insight into realistic strain levels at the beginning of fully plastic response. However, it also is concluded that a deeper analytical representation of the tangential velocity discontinuities is needed. DA - 2001/1// PY - 2001/1// DO - 10.1016/s0022-5096(00)00021-1 VL - 49 IS - 1 SP - 173-208 SN - 1873-4782 KW - grain boundaries KW - crystal plasticity KW - finite strain KW - characteristics KW - finite elements ER - TY - JOUR TI - Nondestructive measurement of a glass transition temperature at spin-cast semicrystalline polymer surfaces AU - Hyun, J AU - Aspnes, DE AU - Cuomo, JJ T2 - MACROMOLECULES AB - ADVERTISEMENT RETURN TO ISSUECommunication to the...Communication to the EditorNEXTNondestructive Measurement of a Glass Transition Temperature at Spin-Cast Semicrystalline Polymer SurfacesJ. Hyun, D. E. Aspnes, and J. J. CuomoView Author Information Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7907 Cite this: Macromolecules 2001, 34, 8, 2395–2397Publication Date (Web):March 9, 2001Publication History Received21 July 2000Revised1 November 2000Published online9 March 2001Published inissue 1 April 2001https://doi.org/10.1021/ma0012797Copyright © 2001 American Chemical SocietyRequest reuse permissions Article Views208Altmetric-Citations18LEARN 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. 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Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (97 KB) Get e-AlertscloseSUBJECTS:Glass transition,Optical properties,Plasma,Polymers,Positron emission tomography Get e-Alerts DA - 2001/4/10/ PY - 2001/4/10/ DO - 10.1021/ma0012797 VL - 34 IS - 8 SP - 2395-2397 SN - 0024-9297 ER - TY - JOUR TI - Morphological characteristics of 1,3 : 2,4-dibenzylidene sorbitol/poly(propylene glycol) organogels AU - Mercurio, DJ AU - Spontak, RJ T2 - JOURNAL OF PHYSICAL CHEMISTRY B AB - The organic gelator 1,3:2,4-dibenzylidene sorbitol (DBS) self-organizes to form a 3-D network stabilized by hydrogen bonds at relatively low concentrations in a variety of nonpolar organic solvents and polymers. The resultant network consists of nanofibrils and is responsible for the physical gelation of the matrix component. In this work, the morphological characteristics of organogels composed of DBS and poly(propylene glycol) (PPG) are investigated as functions of DBS concentration, PPG molecular weight, and temperature through the use of polarized light microscopy, transmission electron microscopy, X-ray diffractometry, and spectrophotometry. Polarized light microscopy reveals thermally reversible features that become increasingly more pronounced with increasing DBS concentration. Electron microscopy verifies that these features arise due to the presence of a DBS nanofibrillar network, with nanofibrils measuring ca. 10 nm in diameter. Comparison of X-ray diffraction patterns of pure DBS crystals and DBS networks from which PPG is removed by supercritical fluid extraction reveals that the DBS nanofibrils are crystalline, differing slightly from the structure of pure DBS. Spectrophotometry is used to probe the temperature-dependent development of the molecular network in DBS/PPG organogels. DA - 2001/3/22/ PY - 2001/3/22/ DO - 10.1021/jp002247o VL - 105 IS - 11 SP - 2091-2098 SN - 1520-5207 ER - TY - JOUR TI - Molecular, nanostructural and mechanical characteristics of lamellar triblock copolymer blends: Effects of molecular weight and constraint AU - Kane, L AU - Norman, DA AU - White, SA AU - Matsen, MW AU - Satkowski, MM AU - Smith, SD AU - Spontak, RJ T2 - MACROMOLECULAR RAPID COMMUNICATIONS AB - While theoretical and experimental efforts have thoroughly addressed microphase-ordered AB diblock copolymer blends with a parent homopolymer (hA or hB) or a second block copolymer, surprisingly few studies have considered comparable ABA triblock copolymers in the presence of hB or an AB diblock copolymer. In this study, we elucidate the roles of additive molecular weight and constraint by examining three matched series of miscible ABA/hB and ABA/AB blends. Self-consistent field theory is employed to analyze molecular characteristics, e. g., segmental distributions, microdomain periods and midblock bridging fractions, as functions of blend composition. Predictions are compared to morphological characteristics discerned by transmission electron microscopy and small-angle X-ray scattering. The corresponding mechanical properties of these blends are measured by dynamic mechanical analysis. The results of this comprehensive work reveal that addition of hB swells the B-lamellae of the ABA copolymer and has a generally deleterious effect on both the dynamic elastic modulus and midblock bridging fraction. In contrast, addition of a lamellar or cylindrical AB copolymer to the same ABA copolymer can promote an increase or decrease in lamellar period and bridging fraction, depending on relative block sizes. DA - 2001/3/26/ PY - 2001/3/26/ DO - 10.1002/1521-3927(20010301)22:5<281::AID-MARC281>3.0.CO;2-G VL - 22 IS - 5 SP - 281-296 SN - 1521-3927 ER - TY - JOUR TI - Investigation of noise in a spectrometer system using a short-arc source AU - Ebert, M AU - Aspnes, DE T2 - REVIEW OF SCIENTIFIC INSTRUMENTS AB - We show that noise can be reduced significantly at certain frequencies in spectrometer systems that use arc-lamp sources if the image of the lamp is oriented perpendicular to the entrance slit of the spectrometer. This appears to be a result of aligning the direction of arc wander along, rather than across, the slit. Data on a specific system show a reduction in the appropriate Fourier component of the power density spectrum by a factor of 4. DA - 2001/8// PY - 2001/8// DO - 10.1063/1.1384423 VL - 72 IS - 8 SP - 3477-3479 SN - 0034-6748 ER - TY - JOUR TI - High temperature elastic constant prediction of some group III-nitrides AU - Reeber, R. R. AU - Wang, K. T2 - MRS Internet Journal of Nitride Semiconductor Research DA - 2001/// PY - 2001/// VL - 6 IS - 3 SP - 1-5 ER - TY - JOUR TI - Growth and oxidation of thin film Al2Cu AU - Son, KA AU - Missert, N AU - Barbour, JC AU - Hren, JJ AU - Copeland, RG AU - Minor, KG T2 - JOURNAL OF THE ELECTROCHEMICAL SOCIETY AB - thin films (∼382 nm) are fabricated by melting and resolidifying Al/Cu bilayers on a on Si(100) substrate in the presence of a ∼3 nm passivating layer. X-ray photoelectron spectroscopy (XPS) measures a 1.0 eV shift of the peak and a 1.6 eV shift of the valance band relative to metallic Cu upon formation. Scanning electron microscopy and electron back-scattered diffraction show that the film is composed of 30-70 μm wide and 10-25 mm long cellular grains with (110) orientation. The atomic composition of the film as estimated by energy dispersive spectroscopy is Al and Cu. XPS scans of taken before and after air exposure indicate that the upper layers undergo further oxidation to even in the presence of ∼5 nm The majority of Cu produced from oxidation is believed to be excluded from the layers, based upon the lack of evidence for metallic Cu in the XPS scans. In contrast to Al/Cu passivated with melting/resolidifying the Al/Cu bilayer without results in phase-segregated dendritic film growth. © 2001 The Electrochemical Society. All rights reserved. DA - 2001/7// PY - 2001/7// DO - 10.1149/1.1376635 VL - 148 IS - 7 SP - B260-B263 SN - 0013-4651 ER - TY - JOUR TI - Characterization of RuO2 electrodes on Zr silicate and ZrO2 dielectrics AU - Zhong, HC AU - Heuss, G AU - Misra, V AU - Luan, HF AU - Lee, CH AU - Kwong, DL T2 - APPLIED PHYSICS LETTERS AB - The rutile stoichiometric phase of RuO2, deposited via reactive sputtering, was evaluated as a gate electrode on chemical vapor deposited ZrO2 and Zr silicate for Si–p-type metal–oxide–semiconductor (PMOS) devices. Thermal and chemical stability of the electrodes was studied at annealing temperatures of 400, 600, and 800 °C in N2. X-ray diffraction was measured to study grain structure and interface reactions. The resistivity of RuO2 films was 65.0 μΩ cm after 800 °C annealing. Electrical properties were evaluated on MOS capacitors, which indicated that the work function of RuO2 was ∼5.1 eV, compatible with PMOS devices. Post-RuO2 gate annealing up to 800 °C, resulted in only a 1.4 Å equivalent oxide thickness (Tox-eq) change and 0.2 V flatband voltage change for Zr silicate and a 4 Å Tox-eq change for ZrO2 dielectrics. Tantalum electrodes were also studied on ZrO2 as a comparison of the stability of RuO2 electrodes. DA - 2001/2/19/ PY - 2001/2/19/ DO - 10.1063/1.1347402 VL - 78 IS - 8 SP - 1134-1136 SN - 1077-3118 ER - TY - JOUR TI - "Standardization" of field emission measurements AU - Zhirnov, , VV AU - Lizzul-Rinne, C AU - Wojak, GJ AU - Sanwald, RC AU - Hren, JJ T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B AB - Interest in field emission and field emission devices has been renewed in the last 5 yr. This increase has been due to work on several new materials systems, which have shown promising field emission (FE) behavior. In turn, this interest gives impetus to the search for new FE sources. In order to move the technology ahead at a faster pace, there is a need for common ground rules and a “standardization” of the data reported so that it can be compared directly in a meaningful way and thereby accelerate the development process. In this article key factors affecting the FE data will be discussed and several parameters are suggested to initiate the process of developing a set of “standardized” FE parameters. A correct, or at least consistent, determination of characteristics such as work function, emission area, and field enhancement form the basis for developing a framework to make meaningful comparisons between different sets of data. DA - 2001/// PY - 2001/// DO - 10.1116/1.1342006 VL - 19 IS - 1 SP - 87-93 SN - 1071-1023 ER -