@article{jagannadham_2019, title={Effect of MoS2 film on memristor characteristics of ZnO film}, volume={126}, ISSN={["1089-7550"]}, DOI={10.1063/1.5126960}, abstractNote={Memory resistive devices using a ZnO dielectric layer are promising due to the transparent nature, lower operating voltage, synthesis compatible with semiconductor processing, and ability to control using magnetic fields. In the present work, niobium incorporated MoS2 films in combination with ZnO are used to form diode-resistor devices with memory. The two device structures p-Si-SiO2/Pt/MoS2(Nb)/ZnO/Ag and p-Si-SiO2/Pt/ZnO/Ag are grown using laser physical vapor deposition. The resistive characteristics are investigated as a function of temperature for comparison. The unipolar I-V characteristics of Pt/ZnO/Ag device films were found to be nonreproducible, and the temperature dependence was irregular for negative polarity. The unipolar I-V characteristics of Pt/MoS2(Nb)/ZnO/Ag device films were found to be reproducible. The temperature dependence of the I-V characteristics was regular for both polarities. The presence of a MoS2 film is found to improve and distinguish the effect of the polarity of the applied field on the unipolar device characteristics by the formation of a p-n device configuration. The conductance in the transition from a low resistance state to a high resistance state was found to follow the Schottky emission with the apparent barrier height being influenced by the p-n junction.}, number={24}, journal={JOURNAL OF APPLIED PHYSICS}, author={Jagannadham, K.}, year={2019}, month={Dec} } @article{jagannadham_2019, title={Low resistance metal contacts on MoS2 films deposited by laser physical vapor deposition}, volume={30}, ISSN={["1573-482X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85065734908&partnerID=MN8TOARS}, DOI={10.1007/s10854-019-01345-6}, number={10}, journal={JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS}, author={Jagannadham, K.}, year={2019}, month={May}, pages={10024–10029} } @article{barsh_bergman_brown_singh_copenhaver_2016, title={Bringing PLOS Genetics Editors to Preprint Servers}, volume={12}, ISSN={["1553-7404"]}, DOI={10.1371/journal.pgen.1006448}, abstractNote={1 HudsonAlpha Institute for Biotechnology, Huntsville, Alabama, United States of America, 2 Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America, 3 Department of Genetics, University of Georgia, Athens, Georgia, United States of America, 4 Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America, 5 Program in Genetics, Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, United States of America, 6 Department of Biology and the Integrative Program for Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, United States of America}, number={12}, journal={PLOS GENETICS}, author={Barsh, Gregory S. and Bergman, Casey M. and Brown, Christopher D. and Singh, Nadia D. and Copenhaver, Gregory P.}, year={2016}, month={Dec} } @article{jagannadham_2016, title={Effect of intermetallic compounds on the thermal conductivity of Ti-Cu composites}, volume={34}, number={2}, journal={Journal of Vacuum Science & Technology. A, Vacuum, Surfaces, and Films}, author={Jagannadham, K.}, year={2016} } @article{jagannadham_2016, title={Thermal conductivity and interface thermal conductance of thin films in Li ion batteries}, volume={327}, journal={Journal of Power Sources}, author={Jagannadham, K.}, year={2016}, pages={565–572} } @article{jagannadham_2016, title={Thermal conductivity changes in titanium-graphene composite upon annealing}, volume={47A}, number={2}, journal={Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science}, author={Jagannadham, K.}, year={2016}, pages={907–915} } @article{jagannadham_2015, title={Determination of modulus of metal films using thermoreflectance}, volume={46A}, number={1}, journal={Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science}, author={Jagannadham, K.}, year={2015}, pages={229–234} } @article{brown_jagannadham_2015, title={Thermal conductivity of MWNT-epoxy composites by transient thermoreflectance}, volume={44}, number={8}, journal={Journal of Electronic Materials}, author={Brown, M. and Jagannadham, K.}, year={2015}, pages={2624–2630} } @article{jagannadham_2015, title={Thermal conductivity of nitride films of Ti, Cr, and W deposited by reactive magnetron sputtering}, volume={33}, number={3}, journal={Journal of Vacuum Science & Technology. A, Vacuum, Surfaces, and Films}, author={Jagannadham, K.}, year={2015} } @article{jagannadham_2014, title={Effect of interfacial interactions on the thermal conductivity and interfacial thermal conductance in tungsten-graphene layered structure}, volume={32}, number={5}, journal={Journal of Vacuum Science & Technology. A, Vacuum, Surfaces, and Films}, author={Jagannadham, K.}, year={2014} } @article{zheng_jagannadham_2014, title={Interface thermal conductance between metal films and copper}, volume={45A}, number={5}, journal={Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science}, author={Zheng, H. and Jagannadham, K.}, year={2014}, pages={2480–2486} } @article{zheng_jagannadham_2014, title={Self heating in Si0.5Ge0.5/Si and GaAs/Si thin film device structures}, volume={99}, journal={Solid-state Electronics}, author={Zheng, H. and Jagannadham, K.}, year={2014}, pages={41–44} } @article{zheng_jaganandham_2014, title={Thermal conductivity and interface thermal conductance in composites of titanium with graphene platelets}, volume={136}, number={6}, journal={Journal of Heat Transfer}, author={Zheng, H. and Jaganandham, K.}, year={2014} } @article{jagannadham_2014, title={Thermal conductivity and interface thermal conductance in films of tungsten-tungsten silicide on Si}, volume={61}, number={6}, journal={IEEE Transactions on Electron Devices}, author={Jagannadham, K.}, year={2014}, pages={1950–1955} } @article{jagannadham_verghese_butler_2014, title={Thermal conductivity changes upon neutron transmutation of B-10 doped diamond}, volume={116}, ISSN={["1089-7550"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84906861630&partnerID=MN8TOARS}, DOI={10.1063/1.4892888}, abstractNote={10B doped p-type diamond samples were subjected to neutron transmutation reaction using thermal neutron flux of 0.9 × 1013 cm−2 s−1 and fast neutron flux of 0.09 × 1013 cm−2 s−1. Another sample of epilayer grown on type IIa (110) single crystal diamond substrate was subjected to equal thermal and fast neutron flux of 1014 cm−2 s−1. The defects in the diamond samples were previously characterized by different methods. In the present work, thermal conductivity of these diamond samples was determined at room temperature by transient thermoreflectance method. The thermal conductivity change in the samples as a function of neutron fluence is explained by the phonon scattering from the point defects and disordered regions. The thermal conductivity of the diamond samples decreased more rapidly initially and less rapidly for larger neutron fluence. In addition, the thermal conductivity in type IIb diamond decreased less rapidly with thermal neutron fluence compared to the decrease in type IIa diamond subjected to fast neutron fluence. It is concluded that the rate of production of defects during transmutation reaction is slower when thermal neutrons are used. The thermal conductivity of epilayer of diamond subjected to high thermal and fast neutron fluence is associated with the covalent carbon network in the composite structure consisting of disordered carbon and sp2 bonded nanocrystalline regions.}, number={8}, journal={JOURNAL OF APPLIED PHYSICS}, author={Jagannadham, K. and Verghese, K. and Butler, J. E.}, year={2014}, month={Aug} } @article{zheng_jagannadham_youssef_2014, title={Thermal conductivity of exfoliated p-type bismuth antimony telluride}, volume={43}, number={2}, journal={Journal of Electronic Materials}, author={Zheng, H. and Jagannadham, K. and Youssef, K.}, year={2014}, pages={320–328} } @article{zheng_jagannadham_2013, title={Influence of dopants on the thermal conductance of GaN-sapphire interface}, volume={60}, number={6}, journal={IEEE Transactions on Electron Devices}, author={Zheng, H. and Jagannadham, K.}, year={2013}, pages={1911–1915} } @article{zheng_jagannadham_2013, title={Influence of laser irradiation and microwave plasma treatment on the thermal properties of graphene platelets}, volume={31}, number={4}, journal={Journal of Vacuum Science & Technology. A, Vacuum, Surfaces, and Films}, author={Zheng, H. and Jagannadham, K.}, year={2013} } @article{zheng_jagannadham_2013, title={Transient thermoreflectance from graphene composites with matrix of indium and copper}, volume={3}, number={3}, journal={AIP Advances}, author={Zheng, H. and Jagannadham, K.}, year={2013} } @article{jagannadham_2013, title={Volume fraction of graphene platelets in copper-graphene composites}, volume={44A}, number={1}, journal={Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science}, author={Jagannadham, K.}, year={2013}, pages={552–559} } @article{jagannadham_2012, title={Thermal conductivity of copper-graphene composite films synthesized by electrochemical deposition with exfoliated graphene platelets}, volume={43}, number={2}, journal={Metallurgical and Materials Transactions B-Process Metallurgy and Materials Processing Science}, author={Jagannadham, K.}, year={2012}, pages={316–324} } @article{jagannadham_2011, title={Influence of laser and thermal treatment on the thermal conductivity of In-graphene composites}, volume={110}, number={9}, journal={Journal of Applied Physics}, author={Jagannadham, K.}, year={2011} } @article{jagannadham_lance_butler_2011, title={Laser annealing of neutron irradiated boron-10 isotope doped diamond}, volume={46}, number={8}, journal={Journal of Materials Science}, author={Jagannadham, K. and Lance, M. J. and Butler, J. E.}, year={2011}, pages={2518–2528} } @article{jagannadham_2011, title={Orientation dependence of thermal conductivity in copper-graphene composites}, volume={110}, number={7}, journal={Journal of Applied Physics}, author={Jagannadham, K.}, year={2011} } @article{jagannadham_2011, title={Thermal conductivity of indium-graphene and indium-gallium-graphene composites}, volume={40}, number={1}, journal={Journal of Electronic Materials}, author={Jagannadham, K.}, year={2011}, pages={25–34} } @article{jagannadham_2010, title={A connection between continuum and atomic description of interface thermal conductance}, volume={108}, number={8}, journal={Journal of Applied Physics}, author={Jagannadham, K.}, year={2010} } @article{sruti_jagannadham_2010, title={Electrical conductivity of graphene composites with In and In-Ga Alloy}, volume={39}, number={8}, journal={Journal of Electronic Materials}, author={Sruti, A. N. and Jagannadham, K.}, year={2010}, pages={1268–1276} } @article{jagannadham_2009, title={Diffusion at a planar interface using continuous distribution of sources}, volume={105}, number={2}, journal={Journal of Applied Physics}, author={Jagannadham, K.}, year={2009} } @article{jagannadham_watkins_lance_riester_lemaster_2009, title={Laser physical vapor deposition of boron carbide films to enhance cutting tool performance}, volume={203}, ISSN={["0257-8972"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-67349177306&partnerID=MN8TOARS}, DOI={10.1016/j.surfcoat.2009.03.049}, abstractNote={Abstract Laser physical vapor deposition was used to deposit thin films of boron carbide on Si (100) and WC–Co substrates at 550 °C under different pressures of methane atmosphere. Grazing incidence X-ray diffraction was used to identify a boron carbide phase, which exhibited weak peaks. The presence of particulates in the size range of 50 nm–3 µm embedded in an amorphous matrix was observed by scanning electron microscopy. Raman spectroscopy indicated that as methane partial pressure was increased during deposition, the amount of disorder with the boron carbide structure also increased. Also, the nanoindentation hardness decreased, while the coefficient of friction and scratch adhesion strength increased. These effects are attributed to an increase in amorphous phase/disorder in the films. Wear tests conducted by machining particleboard using boron carbide coated WC–Co tools in the absence of methane showed the same wear rate as tools coated under higher methane pressures.}, number={20-21}, journal={SURFACE & COATINGS TECHNOLOGY}, author={Jagannadham, K. and Watkins, T. R. and Lance, M. J. and Riester, L. and Lemaster, R. L.}, year={2009}, month={Jul}, pages={3151–3156} } @article{jagannadham_howe_allard_2010, title={Laser physical vapor deposition of nanocrystalline dots using nanopore filters}, volume={98}, ISSN={["1432-0630"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-72149116429&partnerID=MN8TOARS}, DOI={10.1007/s00339-009-5432-7}, number={2}, journal={APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING}, author={Jagannadham, K. and Howe, J. and Allard, L. F.}, year={2010}, month={Feb}, pages={285–292} } @article{jagannadham_berkman_elmasry_2008, title={Thermal conductivity of semi-insulating, p-type, and n-type GaN films on sapphire}, volume={26}, ISSN={["1520-8559"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-42949135532&partnerID=MN8TOARS}, DOI={10.1116/1.2899379}, abstractNote={The thermal conductivity of undoped, n-type, and p-type GaN films deposited on (0001) substrates of sapphire was measured by the 3-ω method in the temperature range between 215 and 300K. The thickness, thermal conductivity, and heat capacity of the individual layers were used to simulate the experimental value of the increment in temperature of the heater using a multilayer model. The thermal conductivity of undoped GaN film was found to be much higher than that of p-type film. Also, the thermal conductivity of n-type GaN film was slightly smaller than that of p-type film. Modeling of the temperature dependence of the thermal conductivity in the films showed that phonon-dopant and three-phonon umklapp scattering are important. Smaller thickness and hence smaller volume fraction of the film with lower dislocation density was also found to be responsible for lower thermal conductivity in n- and p-type GaN films.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Jagannadham, K. and Berkman, E. A. and Elmasry, N.}, year={2008}, month={May}, pages={375–379} } @article{jagannadham_2007, title={Compound semiconductor bonded to AlN heat spreader substrate using graded intermediate layer}, volume={25}, number={3}, journal={Journal of Vacuum Science & Technology. A, Vacuum, Surfaces, and Films}, author={Jagannadham, K.}, year={2007}, pages={536–542} } @article{jagannadham_watkins_lance_2006, title={Interfacial characterization and residual stress analysis in diamond films on LiNbO3}, volume={24}, number={6}, journal={Journal of Vacuum Science & Technology. A, Vacuum, Surfaces, and Films}, author={Jagannadham, K. and Watkins, T. R. and Lance, M. J.}, year={2006}, pages={2105–2112} } @article{jagannadham_reed_lance_watkins_verghese_butler_smirnov_2007, title={Neutron transmutation of B-10 doped diamond}, volume={16}, ISSN={["1879-0062"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33751334357&partnerID=MN8TOARS}, DOI={10.1016/j.diamond.2006.03.019}, abstractNote={Free standing 10B isotope doped diamond films deposited by chemical vapor deposition in a microwave chamber were irradiated to thermal neutron fluence values of 0.32 × 1019, 0.65 × 1019, 1.3 × 1019, and 2.6 × 1019 n/cm2. Cooling of the diamond films was maintained during irradiation. In a separate experiment, neutron irradiation to a total fluence of 2.4 × 1020 n/cm2 with equal fast and thermal neutrons was also performed on a diamond epilayer without cooling during irradiation. The formation of defects in the diamond films was characterized using Raman, FTIR, photoluminescence, electron paramagnetic resonance spectroscopy, and X-ray diffraction. It was found that defect configurations in diamond responsible for an increase in continuum background in the one-phonon region of Raman spectrum were absent in the films that have been cooled. The FTIR peak at 1530 cm− 1 annealed in the sample irradiated to a fluence of 2.6 × 1019 n/cm2 indicating that the sample reached a temperature of 300 °C during irradiation. Absence of characteristic infrared absorption peaks that were observed only upon annealing neutron irradiated diamond is used to conclude that the temperature of the sample during neutron irradiation to a fluence of 2.6 × 1019 n/cm2 was well below 650 °C needed for mobility of defects and accumulation of stable unrecoverable damage. On the other hand, results from diamond epilayer subjected to equal thermal and fast neutron fluence of 2.4 × 1020 n/cm2 and without cooling showed that defects formed from displaced carbon atoms became mobile and formed complex configurations of irrecoverable damage. Electrical conductance of the unirradiated and irradiated diamond samples was measured as a function of temperature to determine the compensation of the p-type by the n-type charge carriers.}, number={1}, journal={DIAMOND AND RELATED MATERIALS}, author={Jagannadham, K. and Reed, M. L. and Lance, M. J. and Watkins, T. R. and Verghese, K. and Butler, J. E. and Smirnov, A.}, year={2007}, month={Jan}, pages={50–62} } @article{scheffing_jagannadham_yim_bourham_farmer_haslam_day_fix_yang_2006, title={Properties of titanium-nitride for high-level waste packaging enhancement}, volume={156}, ISSN={["0029-5450"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33751356018&partnerID=MN8TOARS}, DOI={10.13182/NT156-213}, abstractNote={A feasibility study of applying titanium-nitride (TiN) coating onto waste package surfaces was performed as part of efforts to enhance the long-term performance of high-level waste packages. The hypothesis examined in the study is that a successful TiN coating would provide an effective mass-transport barrier thus preventing corrosion. In the present work, single-layer TiN and multiple-layer TiN + Ti, TiN + Ti + TiN, and ZrO2 + TiN were deposited on Type 316L stainless steel substrates. The coated samples were tested for corrosion properties in different types of water using polarization and weight loss tests. Results of corrosion testing are presented and discussed.}, number={2}, journal={NUCLEAR TECHNOLOGY}, author={Scheffing, C. C. and Jagannadham, K. and Yim, M. -S. and Bourham, M. A. and Farmer, J. C. and Haslam, J. J. and Day, S. D. and Fix, D. V. and Yang, N. Y.}, year={2006}, month={Nov}, pages={213–221} } @article{jagannadham_2006, title={Thermal conductivity of AlN-diamond particulate composite films on silicon}, volume={24}, number={4}, journal={Journal of Vacuum Science & Technology. A, Vacuum, Surfaces, and Films}, author={Jagannadham, K.}, year={2006}, pages={895–899} } @article{reed_reed_jagannadham_verghese_bedair_el-masry_butler_2004, title={Electrical characterization of B-10 doped diamond irradiated with low thermal neutron fluence}, volume={22}, ISSN={["1520-8559"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-4344661941&partnerID=MN8TOARS}, DOI={10.1116/1.1763910}, abstractNote={A sample of B10 isotope doped diamond was neutron irradiated to a thermal fluence of 1.3×1019 neutron cm−2. The diamond sample was cooled continuously during irradiation in a nuclear reactor. Li7 is formed by nuclear transmutation reaction from B10. Characterization for electrical conductance in the temperature range of 160 K200 K) and p-type surface conductance at lower temperature (T<200 K). The irradiated sample showed decreasing conductance below 230 K and increasing conductance above 230 K with increasing temperature. Furthermore, the conductance showed a decrease above 400 K followed by an increase above 500 K. The observed behavior below 400 K with increase in temperature is interpreted in terms of compensation of surface p-type carriers by n-type bulk carriers generated from Li7 that is formed by nuclear transmutation reaction from B10 atoms. Also, compensation of n-type carriers from Li7 by p-type carriers from B10 is used to interpret the conductance above 400 K. A low concentration of radiation induced defects, absence of defect complexes, and the low activation energy of n-type Li7 are thought responsible for the observed variation of conductance in the irradiated diamond. The present results illustrate that neutron transmutation from B10 doped diamond is a useful method to achieve n-type conductivity in diamond.}, number={4}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Reed, ML and Reed, MJ and Jagannadham, K and Verghese, K and Bedair, SM and El-Masry, N and Butler, JE}, year={2004}, pages={1191–1194} } @article{jagannadham_lance_watkins_2004, title={Growth of diamond film on single crystal lithium niobate for surface acoustic wave devices}, volume={22}, number={4}, journal={Journal of Vacuum Science & Technology. A, Vacuum, Surfaces, and Films}, author={Jagannadham, K. and Lance, M. J. and Watkins, T. R.}, year={2004}, pages={1105–1109} } @article{makala_jagannadham_sales_2003, title={Pulsed laser deposition of Bi2Te3-based thermoelectric thin films}, volume={94}, ISSN={["1089-7550"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0141990549&partnerID=MN8TOARS}, DOI={10.1063/1.1600524}, abstractNote={Thin films of p-type Bi0.5Sb1.5Te3, n-type Bi2Te2.7Se0.3, and n-type (Bi2Te3)90(Sb2Te3)5(Sb2Se3)5 (with 0.13 wt % SbI3) were deposited on substrates of mica and aluminum nitride (on silicon) using pulsed laser ablation at substrate temperatures between 300 °C to 500 °C. The films were characterized using x-ray diffraction and transmission electron microscopy for crystalline quality and epitaxial growth on the substrates. The surface morphology and microstructure were examined using scanning electron microscopy. X-ray mapping and energy-dispersive spectroscopy were performed to determine nonstoichiometry in the composition and homogeneity. The quality of the films, in terms of stoichiometric composition and crystal perfection, was studied as a function of growth temperature and laser fluence. The values of the Seebeck coefficient, electrical resistivity, and Hall mobility in the thin films were measured and compared with those in the bulk. Thermoelectric figure of merit of the films was evaluated from the measured parameters. Correlation of the thermoelectric properties, with the crystalline quality and stoichiometric composition of the films, showed the advantages of pulsed laser deposition of the multicomponent thermoelectric thin films. The results illustrate that laser physical vapor deposition is a suitable choice for deposition of multicomponent thermoelectric films. However, optimization of target composition, substrate temperature, and annealing of the films after deposition were found necessary to maintain the desired stoichiometry and low defect density. AlN/Si substrates provided better quality films compared to substrates of mica. Poor adhesion and cracking of the films on mica were found to be detrimental factors. Films deposited on AlN/Si substrates were found to show higher carrier mobility and higher values of Seebeck coefficient.}, number={6}, journal={JOURNAL OF APPLIED PHYSICS}, author={Makala, RS and Jagannadham, K and Sales, BC}, year={2003}, month={Sep}, pages={3907–3918} } @article{raghuveer_yoganand_jagannadham_lemaster_bailey_2002, title={Improved CVD diamond coatings on WC-Co tool substrates}, volume={253}, ISSN={["0043-1648"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0036951335&partnerID=MN8TOARS}, DOI={10.1016/S0043-1648(02)00244-2}, abstractNote={Tungsten carbide tools with different cobalt concentrations (3 and 6%) have been treated with different surface cleaning procedures for deposition of diamond and multilayer diamond composite films. Cleaning with organic solvents, surface etching to remove cobalt from the surface, and hydrogen plasma etching to decarburize WC and etch remove cobalt have been used in combination to improve the adhesion of diamond films deposited on the tool substrates. Diamond layers are deposited by microwave plasma chemical vapor deposition (MPCVD) after introducing surface nucleation by suspension with sub-micron size diamond crystallites. TiN and TiC films are deposited as intermediate layers that prevent diffusion of cobalt or as embedding layers that also anchor diamond crystallites to the tool substrate. A continuous top layer of diamond was deposited for different periods of time (15–36 h) to obtain diamond film thickness ranging from 15 to 36 μm. The performance of diamond-coated tools has been tested by machining particleboard. The tool surfaces were characterized using measurements of wear of the cutting edge. Microstructural characterization using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) of the composite layers on the tool surfaces is performed. The quantitative evaluation of wear and microstructural characterization were used to determine the mechanisms of wear of the cutting edge. The results are used to conclude the diamond tool coating procedure that provides the best performance in machining particleboard.}, number={11-12}, journal={WEAR}, author={Raghuveer, MS and Yoganand, SN and Jagannadham, K and Lemaster, RL and Bailey, J}, year={2002}, month={Dec}, pages={1194–1206} } @article{yoganand_jagannadham_karoui_wang_2002, title={Integrated AlN/diamond heat spreaders for silicon device processing}, volume={20}, ISSN={["0734-2101"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0036863138&partnerID=MN8TOARS}, DOI={10.1116/1.1513643}, abstractNote={Growth and characterization of AlN and diamond films on the backside of a Si (100) wafer and the integration of AlN/diamond heat spreaders into silicon device technology is investigated. AlN film was deposited by pulsed dc reactive magnetron sputtering at 600 °C and diamond film was deposited by microwave plasma chemical vapor deposition at 900 °C. The films were characterized by x-ray diffraction and transmission electron microscopy for crystalline quality, by scanning electron microscopy for morphology, and by infrared thermography for heat spreading characteristics. The heat spreading characteristics of the silicon wafer with the composite AlN/diamond films were found to be superior to that of wafers with no heat spreaders or to the wafers with either single layer diamond or single layer AlN heat spreaders. Deep level transient spectroscopy and secondary ion mass spectroscopy were performed on the samples with and without the heat spreader to determine the concentration of the impurities that may have been introduced during deposition of AlN or diamond. The results showed that the purity of the wafers is not altered due to the deposition of AlN and diamond and subsequent device processing steps such as high temperature oxidation. The device characteristics were studied by fabrication of Schottky diodes on the wafers with the composite AlN/diamond heat spreader and compared with that of devices on wafers with no heat spreader. The device characteristics were found to be similar and unaffected by integration with an AlN/diamond heat spreader. Integration of AlN/diamond heat spreaders with silicon device processing has been shown to be successful.}, number={6}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS}, author={Yoganand, SN and Jagannadham, K and Karoui, A and Wang, H}, year={2002}, pages={1974–1982} } @article{yoganand_raghuveer_jagannadham_wu_karoui_rozgonyi_2002, title={Multilayer TiC/TiN diffusion barrier films for copper}, volume={80}, ISSN={["1077-3118"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79955988332&partnerID=MN8TOARS}, DOI={10.1063/1.1430027}, abstractNote={TiC/TiN thin films deposited by reactive magnetron sputtering on Si (100) substrates were investigated by transmission electron microscopy for microstructure and by deep level transient spectroscopy (DLTS) for diffusion barrier against copper. TiN thin films deposited on Si substrates at a substrate temperature of 600 °C were textured, and TiC thin films deposited at the same temperature were polycrystalline. TiC/TiN multilayer films also showed the same characteristics with the formation of an additional interaction layer. The diffusion barrier characteristics of the TiC/TiN/Si were determined by DLTS and the results showed that the films completely prevented diffusion of copper into Si.}, number={1}, journal={APPLIED PHYSICS LETTERS}, author={Yoganand, SN and Raghuveer, MS and Jagannadham, K and Wu, L and Karoui, A and Rozgonyi, G}, year={2002}, month={Jan}, pages={79–81} } @article{jagannadham_watkins_dinwiddie_2002, title={Novel heat spreader coatings for high power electronic devices}, volume={37}, ISSN={["0022-2461"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0036531178&partnerID=MN8TOARS}, DOI={10.1023/A:1014568512077}, number={7}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Jagannadham, K and Watkins, TR and Dinwiddie, RB}, year={2002}, month={Apr}, pages={1363–1376} } @article{jagannadham_wang_2002, title={Thermal resistance of interfaces in AlN-diamond thin film composites}, volume={91}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0036469393&partnerID=MN8TOARS}, DOI={10.1063/1.1428103}, abstractNote={The effective thermal conductivity of single and multilayer AlN/diamond composite films deposited on silicon substrate with a planar interface is determined experimentally. As a result of the small thickness and the good crystalline quality of the AlN and diamond films, the contribution to the effective thermal resistivity from the films remained very small and enabled the evaluation of the thermal barrier resistance associated with the interfaces. The interfacial thermal resistance of AlN/Si, diamond/Si, and AlN/diamond interfaces was evaluated from the experimental measurements of the effective thermal conductivity of the layered structures. The results show that amorphous regions formed along the interfaces are responsible for high thermal resistance in the layered structures. Modeling of the interfacial thermal resistance has been carried out to explain the effective thermal conductivity of the single and multilayer AlN/diamond composite films in terms of the microstructure of the interfaces.}, number={3}, journal={Journal of Applied Physics}, author={Jagannadham, K. and Wang, H.}, year={2002}, pages={1224–1235} } @article{jagannadham_verghese_butler_2001, title={Neutron transmutation of B-10 isotope-doped diamond}, volume={78}, ISSN={["0003-6951"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0042331197&partnerID=MN8TOARS}, DOI={10.1063/1.1342207}, abstractNote={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.}, number={4}, journal={APPLIED PHYSICS LETTERS}, author={Jagannadham, K and Verghese, K and Butler, JE}, year={2001}, month={Jan}, pages={446–447} } @article{sharma_narayan_narayan_jagannadham_2000, title={Structural and tribological characteristics of diamond-like carbon films deposited by pulsed laser ablation}, volume={77}, ISSN={["0921-5107"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0034250566&partnerID=MN8TOARS}, DOI={10.1016/s0921-5107(00)00434-7}, abstractNote={Diamond-like carbon (DLC) films were deposited by pulsed laser ablation (PLA) on Si (100) and Ti–6Al–4V alloy substrates at four different temperatures. The bonding characteristics of the films were studied by X-ray photoelectron (XPS) and Raman spectroscopy techniques. The ratio of tetrahedral to trigonally coordinated carbon atoms was estimated by XPS successfully. The fraction of tetrahedrally bonded atoms in the films deposited on Si at room temperature was estimated to be ∼63 at.% which decreased to ∼33 at.% as the substrate temperature increased to 400°C. The Raman spectroscopy results of these specimens agree qualitatively with these observations. Also, using Raman spectroscopy, the residual compressive stress was also estimated in fully adherent films on Si substrate to be ∼3 GPa with reference to the value of stress present in a free-standing peeled off film from the Ti-alloy substrate. This value is consistent with the residual stresses estimated in the earlier results. The abrasive wear rates have been correlated during the initial stages of the well adhered films with the sp3/sp2 ratios. The importance of suitable dopants and the interfacial interlayers in reducing internal compressive stresses in these films is discussed.}, number={2}, journal={MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY}, author={Sharma, AK and Narayan, RJ and Narayan, J and Jagannadham, K}, year={2000}, month={Aug}, pages={139–143} } @article{oktyabrsky_kalyanaraman_jagannadham_narayan_1999, title={Dislocation structure of low-angle grain boundaries in YBa2Cu3O7-delta/MgO films}, volume={14}, ISSN={["0884-2914"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032678410&partnerID=MN8TOARS}, DOI={10.1557/JMR.1999.0369}, abstractNote={Grain boundaries in laser-deposited YBa2Cu3O7−δ(YBCO)/MgO thin films have been investigated by high-resolution transmission electron microscopy. The films exhibit perfect texturing with YBCO(001)/MgO(001) giving rise to low-angle [001] tilt grain boundaries resulting from the grains with thecaxis normal to the substrate surface and with misorientation in thea-bplane. The atomic structure of the grain boundaries was analyzed by using a dislocation model. Low-angle grain boundaries have been found to be aligned along (100) and (110) interface planes. For the (110) boundary plane, the low-energy dislocation configuration was found to consist of an array of alternating [100] and [010] dislocations. We have calculated the energy of various configurations and shown that the energy of the (110) boundary with dissociated dislocations is comparable to that of the (100) boundary, which explains the coexistence of (100) and (110) interface facets along the boundary. We have also modeled critical current transport through grain boundaries with various structures and found that the low-energy (110) grain boundary with dissociated dislocation array is expected to transport a lower superconducting current (by 25% for 6° misorientation) than (100) boundaries.}, number={7}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Oktyabrsky, S and Kalyanaraman, R and Jagannadham, K and Narayan, J}, year={1999}, month={Jul}, pages={2764–2772} } @article{jagannadham_1999, title={Model of interfacial thermal resistance of diamond composites}, volume={17}, ISSN={["1520-8559"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0033465465&partnerID=MN8TOARS}, DOI={10.1116/1.581597}, abstractNote={The effective thermal conductivity of diamond and aluminum nitride layered composites was analyzed for three different types of interfaces. A sharp interface with a stepwise discontinuity, a graded interface with a linear variation and a diffused interface with a minimum or a maximum in thermal conductivity across the interface were considered. The results of the modeling analysis were used to explain the experimental results described in the literature of improved heat spreader characteristics of diamond and aluminum nitride composites.}, number={2}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Jagannadham, K}, year={1999}, pages={373–379} } @article{mallika_ramamohan_jagannadham_komanduri_1999, title={On the growth of polycrystalline diamond on transition metals by microwave-plasma-assisted chemical vapour deposition}, volume={79}, ISSN={["0141-8637"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032664013&partnerID=MN8TOARS}, DOI={10.1080/13642819908205738}, abstractNote={Abstract The role of transition-metal substrates on the deposition of polycrystalline diamond was investigated using a microwave—plasma-assisted chemical vapour deposition process. Diamond deposition was carried out on the transition elements of the first series (3d block) and on the elements belonging to groups VB and VIB. It was found that the chemical nature of the transition metals plays an important role in the formation of diamond. Similarity in morphological features was observed on the diamond films grown on the substrates belonging to the same group. Micro-Raman (μ-Raman) spectroscopy indicated that diamond films on substrates belonging to groups VB and VIB have lower internal stresses than those deposited on group VIII. An attempt was made to relate the trends observed from the μ-Raman spectroscopy to the chemical properties of the transition elements. The mechanism of diamond growth seem to vary across the period. Elements belonging to the first half of the transition series, namely Ti, V. Nb, ...}, number={4}, journal={PHILOSOPHICAL MAGAZINE B-PHYSICS OF CONDENSED MATTER STATISTICAL MECHANICS ELECTRONIC OPTICAL AND MAGNETIC PROPERTIES}, author={Mallika, K and Ramamohan, TR and Jagannadham, K and Komanduri, R}, year={1999}, month={Apr}, pages={593–624} } @article{jagannadham_wilsdorf_weertman_1998, title={Dislocations at ductile/plastic crack tips: in-situ TEM observations}, volume={1}, ISSN={["1432-8917"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-24044483938&partnerID=MN8TOARS}, DOI={10.1007/s100190050050}, abstractNote={In-situ observations of dislocation structures ahead of crack tips in TEM metal foils are reviewed. Two cases are compared in particular: Structure development during in-situ straining to failure of (i) electron-transparent foils ahead of the tip of a growing crack that spreads from the thinnest regions or perforations and (ii) initially non-transparent thick foils. In the latter case cracks formed only after substantial in-situ straining, and they propagated along dislocation cell walls via repeated stimulated crack nucleation ahead of the tip. This behavior was shown to adequately simulate bulk behavior and such cracks do not exhibit dislocation-free zones at their tips. By contrast, dislocation-free regions along ligaments formed by crack propagation and observed in thin (e.g. about 100 nm or less) TEM foils are found to be artifacts due to strong dislocation image forces. These image forces at the same time limit mutual dislocation interactions to the thickness of the foil, and rotate the dislocations to be normal to the foil plane, meanwhile straightening them. This behavior has no correspondence to conditions at real cracks in bulk materials. Theoretical expressions are derived for the dislocation densities ahead of crack tips that give rise to long-range and shorter range stress fields in mode I crack tip configurations, respectively.}, number={4}, journal={MATERIALS RESEARCH INNOVATIONS}, author={Jagannadham, K and Wilsdorf, HGF and Weertman, J}, year={1998}, month={Feb}, pages={254–264} } @article{jagannadham_1998, title={Multilayer diamond heat spreaders for electronic power devices}, volume={42}, ISSN={["0038-1101"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032304412&partnerID=MN8TOARS}, DOI={10.1016/S0038-1101(98)00216-0}, abstractNote={Single layer diamond and multilayer diamond heat spreader substrates are prepared and bonded to device wafers of silicon and gallium arsenide. Metallization schemes for the diamond surface and the backside of the device wafers are described. Bonding of the device wafers to the diamond substrates using the high thermal conductivity gold–tin eutectic solder is carried out. Characterization of the bond for the distribution of different elements in the metallization layers and the solder, for the presence of microscopic defects such as voids and cracks, for the adhesion strength and for the stability of the bond under thermal cycling is performed. The heat spreader characteristics of the substrates with single and multlayer diamond are determined using infrared imaging of the bonded device wafers and compared with that of wafers bonded to metal substrates. Modeling and analysis of the effectivethermal conductivity showed that the multilayer diamond substrates are better heat spreaders and reduce the device temperature so that the life of the electronic devices is prolonged.}, number={12}, journal={SOLID-STATE ELECTRONICS}, author={Jagannadham, K}, year={1998}, month={Dec}, pages={2199–2208} } @article{jagannadham_sharma_wei_kalyanraman_narayan_1998, title={Structural characteristics of AIN films deposited by pulsed laser deposition and reactive magnetron sputtering: A comparative study}, volume={16}, ISSN={["0734-2101"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032370406&partnerID=MN8TOARS}, DOI={10.1116/1.581425}, abstractNote={Aluminum nitride films have been deposited on Si(111) substrates at different substrate temperatures using two techniques; pulsed laser deposition or reactive magnetron sputtering. The films deposited by either of the techniques have been characterized by x-ray diffraction and transmission electron microscopy to determine the crystalline quality, grain size, and epitaxial growth relation with respect to the substrate. The bonding characteristics and the residual stresses present in the films have been evaluated using Raman and Fourier transform infrared spectroscopy. Secondary ion mass spectrometry has been performed to determine the nitrogen stoichiometry and the presence of impurities such as oxygen and silicon. The adhesion strength of the AlN films to the silicon substrate and the wear resistance have been determined by scratch test and a specially designed microscopic wear test. A comparison of the different characteristic features associated with the AlN films deposited by pulsed laser deposition or magnetron sputtering is presented with particular emphasis to electronic and tribological applications.}, number={5}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS}, author={Jagannadham, K and Sharma, AK and Wei, Q and Kalyanraman, R and Narayan, J}, year={1998}, pages={2804–2815} }