@misc{linthicum_gehrke_thomson_carlson_rajagopal_davis_2008, title={Pendeoepitaxial gallium nitride semiconductor layers on silicon carbide substrates}, volume={7,378,684}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Linthicum, K. J. and Gehrke, T. and Thomson, D. B. and Carlson, E. P. and Rajagopal, P. and Davis, R. F.}, year={2008} }
 @misc{zheleva_thomson_smith_linthicum_gehrke_davis_2007, title={Methods of fabricating gallium nitride semiconductor layers by lateral growth into trenches}, volume={7,195,993}, number={2007 Mar. 27}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Zheleva, T. and Thomson, D. B. and Smith, S. A. and Linthicum, K. J. and Gehrke, T. and Davis, R. F.}, year={2007} }
 @article{chang_li_thomson_davis_2007, title={Phonon-assisted stimulated emission from pendeoepitaxy GaN stripes grown on 6H-SiC substrates}, volume={91}, number={5}, journal={Applied Physics Letters}, author={Chang, Y. C. and Li, Y. L. and Thomson, D. B. and Davis, R. F.}, year={2007} }
 @misc{zheleva_thomson_smith_linthicum_gehrke_davis_2005, title={Second gallium nitride layers that extend into trenches in first gallium nitride layers}, volume={6,897,483}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Zheleva, T. and Thomson, D. B. and Smith, S. A. and Linthicum, K. J. and Gehrke, T. and Davis, R. F.}, year={2005} }
 @misc{linthicum_gehrke_davis_thomson_tracy_2003, title={Methods of fabricating gallium nitride microelectronic layers on silicon layers}, volume={6,602,764}, number={2003 Aug. 5}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Linthicum, K. J. and Gehrke, T. and Davis, R. F. and Thomson, D. B. and Tracy, K. M.}, year={2003} }
 @article{mcginnis_thomson_banks_preble_davis_lamb_2003, title={Supersonic jet epitaxy of gallium nitride using triethylgallium and ammonia}, volume={21}, ISSN={["0734-2101"]}, DOI={10.1116/1.1532736}, abstractNote={Gallium nitride (GaN) films were grown on GaN(0001)/AlN/6H–SiC composite substrates at 700–780 °C by supersonic jet epitaxy using triethylgallium (TEG) and NH3. TEG was seeded in He and N2 supersonic free jets to obtain kinetic energies of ∼2.1 and ∼0.5 eV, respectively, and NH3 was supplied from a variable leak valve. Higher TEG beam intensities (by about a factor of 5) were obtained by seeding in He. In situ reflection high-energy electron diffraction indicated a transition from three-dimensional to two-dimensional (2D) growth between 730 and 750 °C for films grown using TEG seeded in He and a constant NH3/TEG flux ratio. Ex situ atomic force microscopy of films grown at 730 and 750 °C revealed smooth surfaces comprised of quasi-2D islands with irregular perimeters. Cross-sectional transmission electron microscopy evidenced that the film grown at 750 °C was homoepitaxial α-GaN with a high density of planar lattice defects. Secondary ion mass spectrometry detected high residual carbon concentrations in the films. The GaN growth rate at 750 °C was found to depend on TEG flux and NH3 pressure in a manner consistent with Langmuir–Hinshelwood kinetics. Films grown under NH3-rich conditions were faceted and microscopically rough, whereas nonfaceted, basal-plane growth was observed under Ga-rich conditions. The first-order dependence of growth rate on TEG flux under NH3-rich conditions was used to estimate Ga incorporation efficiencies for high- and low-energy TEG beams. The Ga incorporation efficiency is lower for high-energy TEG beams, consistent with a decrease in the sticking coefficient for dissociative chemisorption.}, number={1}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={McGinnis, AJ and Thomson, D and Banks, A and Preble, E and Davis, RF and Lamb, HH}, year={2003}, pages={294–301} }
 @article{usov_parikh_thomson_davis_2002, title={Effect of implantation temperature on damage accumulation in Ar-implanted GaN}, volume={7}, number={9}, journal={MRS Internet Journal of Nitride Semiconductor Research}, author={Usov, I. and Parikh, N. and Thomson, D. B. and Davis, R. F.}, year={2002}, pages={9–1} }
 @article{shin_arkun_thomson_miraglia_preble_schlesser_wolter_sitar_davis_2002, title={Growth and decomposition of bulk GaN: role of the ammonia/nitrogen ratio}, volume={236}, ISSN={["0022-0248"]}, DOI={10.1016/S0022-0248(02)00825-4}, abstractNote={Gallium nitride crystals grown via vapor-phase transport processes that incorporate ammonia as the only source of nitrogen below atmospheric pressures experience significant surface roughening and the eventual cessation of growth. Investigations of these phenomena in this research, and in the context of the discovery of a non-ceasing process route to larger GaN crystals, showed that the RMS values of the surface roughness of single crystal GaN (0 0 0 1) films exposed to pure ammonia flowing at 60 sccm for 2 h at 1130°C increased from the as-received value of 3.7–6.8 nm, 21.4 and 32.6 nm at 100, 430 and 760 Torr, respectively. Quadrupole mass spectrometry revealed that the concentrations of H2 and N2 measurably increased at pressures above 400 Torr. The primary reason for the increased roughness above 430 Torr was the enhanced etching of GaN via reaction with atomic and molecular hydrogen derived from the dissociation of the ammonia. At lower pressures, the decomposition of the GaN via the formation and evaporation of N2 and Ga increased in importance relative to etching for enhancing surface roughness. Dilution with nitrogen reduced the amount of hydrogen generated from the dissociation of the ammonia. The GaN surface annealed at 1130°C and 430 Torr in ammonia diluted with 33 vol% N2 maintained the smoothest surface with a nominal RMS value of 10.4 nm. Mixtures with higher and lower percentages of N2 showed enhanced roughness under the same conditions. Use of this optimum gas mixture also allowed the seeded growth of a 1.5×1.5×2.0 mm3 GaN crystal and a 2.3×1.8×0.3 mm3 thick platelet with neither observable decomposition nor cessation of the growth over periods of 36 and 48 h, respectively.}, number={4}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Shin, H and Arkun, E and Thomson, DB and Miraglia, P and Preble, E and Schlesser, R and Wolter, S and Sitar, Z and Davis, RF}, year={2002}, month={Mar}, pages={529–537} }
 @article{shin_thomson_schlesser_davis_sitar_2002, title={High temperature nucleation and growth of GaN crystals from the vapor phase}, volume={241}, ISSN={["1873-5002"]}, DOI={10.1016/S0022-0248(02)01290-3}, abstractNote={Abstract A vapor phase growth process involving the reaction of Ga vapor and ammonia has been used to grow needle- and platelet-shaped single crystals of GaN at 1130°C. Introduction of the NH 3 only at high temperatures reduced the nucleation density, minimized the amount of GaN crust on the Ga source and resulted in larger crystals. A processing map has been constructed with respect to ammonia flow rate and total pressure at 1130°C to achieve control of growth in different crystallographic directions. Platelet growth of GaN was favored using low V/III ratios achieved via low ammonia flow rates and/or low total ammonia pressures and/or an increase in the Ga source temperature. Crystals with aspect ratios c / a}, number={4}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Shin, H and Thomson, DB and Schlesser, R and Davis, RF and Sitar, Z}, year={2002}, month={Jun}, pages={404–415} }
 @misc{gehrke_linthicum_davis_thomson_2002, title={High temperature pendeoepitaxial methods of fabricating gallium nitride semiconductor layers on sapphire substrates}, volume={6,489,221}, number={2002 Dec. 3}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Gehrke, T. and Linthicum, K. J. and Davis, R. F. and Thomson, D. B.}, year={2002} }
 @misc{linthicum_gehrke_thomson_carlson_rajagopal_davis_2002, title={Pendeoepitaxial gallium nitride semiconductor layers on silicon carbide substrates}, volume={6,462,355}, number={2002 Oct. 8}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Linthicum, K. J. and Gehrke, T. and Thomson, D. B. and Carlson, E. P. and Rajagopal, P. and Davis, R. F.}, year={2002} }
 @article{danielsson_zetterling_ostling_linthicum_thomson_nam_davis_2002, title={The influence of band offsets on the IV characteristics for GaN/SiC heterojunctions}, volume={46}, ISSN={["1879-2405"]}, DOI={10.1016/S0038-1101(01)00346-X}, abstractNote={Abstract GaN/SiC heterojunctions can improve the performance considerably for bipolar transistors based on SiC technology. In order to fabricate such devices with a high current gain, the origin of the low turn-on voltage for the heterojunction has to be investigated, which is believed to decrease the minority carrier injection considerably. In this work heterojunction diodes are compared and characterized. For the investigated diodes, the GaN layers have been grown by molecular beam epitaxy (MBE), metal organic chemical vapor deposition, and hydride vapor phase epitaxy. A diode structure fabricated with MBE is presented here, whereas others are collected from previous publications. The layers were grown either with a low temperature buffer, AlN buffer, or without buffer layer. The extracted band offsets are compared and included in a model for a recombination process assisted by tunneling, which is proposed as explanation for the low turn-on voltage. This model was implemented in a device simulator and compared to the measured structures, with good agreement for the diodes with a GaN layer grown without buffer layer. In addition the band offset has been calculated from Schottky barrier measurements, resulting in a type II band alignment with a conduction band offset in the range 0.6–0.9 eV. This range agrees well with the values extracted from capacitance–voltage measurements.}, number={6}, journal={SOLID-STATE ELECTRONICS}, author={Danielsson, E and Zetterling, CM and Ostling, M and Linthicum, K and Thomson, DB and Nam, OH and Davis, RF}, year={2002}, month={Jun}, pages={827–835} }
 @article{mcginnis_thomson_davis_chen_michel_lamb_2001, title={In situ cleaning of GaN/6H-SiC substrates in NH3}, volume={222}, ISSN={["0022-0248"]}, DOI={10.1016/s0022-0248(00)00947-7}, abstractNote={Abstract 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.}, number={3}, journal={JOURNAL OF CRYSTAL GROWTH}, author={McGinnis, AJ and Thomson, D and Davis, RF and Chen, E and Michel, A and Lamb, HH}, year={2001}, month={Jan}, pages={452–458} }
 @article{mcginnis_thomson_davis_chen_michel_lamb_2001, title={Kinetics and gas-surface dynamics of GaN homoepitaxial growth using NH3-seeded supersonic molecular beams}, volume={494}, ISSN={["1879-2758"]}, DOI={10.1016/S0039-6028(01)01466-2}, abstractNote={Abstract 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 >2×10 15 cm −2 s −1 at the substrate) are produced for low seeding percentages (}, number={1}, journal={SURFACE SCIENCE}, author={McGinnis, AJ and Thomson, D and Davis, RF and Chen, E and Michel, A and Lamb, HH}, year={2001}, month={Nov}, pages={28–42} }
 @misc{zheleva_thomson_smith_linthicum_gehrke_davis_2001, title={Methods of fabricating gallium nitride semiconductor layers by lateral growth from sidewalls into trenches, and gallium nitride semiconductor structures fabricated thereby}, volume={6,265,289}, number={2001 July 24}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Zheleva, T. and Thomson, D. B. and Smith, S. A. and Linthicum, K. J. and Gehrke, T. and Davis, R. F.}, year={2001} }
 @misc{linthicum_gehrke_thomson_carlson_rajagopal_davis_2001, title={Pendeoepitaxial gallium nitride semiconductor layers on silicon carbide substrates}, volume={6,177,688}, number={2001 Jan. 23}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Linthicum, K. J. and Gehrke, T. and Thomson, D. B. and Carlson, E. P. and Rajagopal, P. and Davis, R. F.}, year={2001} }
 @article{danielsson_zetterling_ostling_lee_linthicum_thomson_nam_davis_2000, title={Dry etching and metallization schemes in a GaN/SiC heterojunction device process}, volume={338}, number={3}, journal={Materials Science Forum}, author={Danielsson, E. and Zetterling, C. M. and Ostling, M. and Lee, S. K. and Linthicum, K. J. and Thomson, D. B. and Nam, O. H. and Davis, R. F.}, year={2000}, pages={1049–1052} }
 @article{smith_lampert_rajagopal_banks_thomson_davis_2000, title={Selective etching of GaN over AlN using an inductively coupled plasma and an O-2/Cl-2/Ar chemistry}, volume={18}, ISSN={["1520-8559"]}, DOI={10.1116/1.582270}, abstractNote={An alternative method for achieving etching selectivity between GaN and AlN has been demonstrated. The etch rate of AlN was significantly decreased by the addition of a low concentration of O2 to a Cl2–Ar mixture in an inductively coupled plasma (ICP) etching system. The etch rate of GaN in the O2-containing plasma was approximately 15% less than the plasma without the O2 for the same parameters. The pressure and the ICP power were varied to achieve a maximum selectivity of 48 at a pressure of 10 mTorr, a direct current bias of −150 V, and an ICP power of 500 W. The etch rates of GaN and AlN at these parameters were 4800 and 100 Å/min, respectively.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Smith, SA and Lampert, WV and Rajagopal, P and Banks, AD and Thomson, D and Davis, RF}, year={2000}, pages={879–881} }
 @article{ronning_linthicum_carlson_hartlieb_thomson_gehrke_davis_1999, title={Characterization of Be-implanted GaN annealed at high temperatures}, volume={4S1}, number={G3.17}, journal={MRS Internet Journal of Nitride Semiconductor Research}, author={Ronning, C. and Linthicum, K. J. and Carlson, E. P. and Hartlieb, P. J. and Thomson, D. B. and Gehrke, T. and Davis, R. F.}, year={1999} }
 @article{elliott s.l._humphreys c.j._considine l._w.b._1999, title={FEG-SEM imaging of semiconductor dopant contrast}, volume={164}, ISBN={0750306505}, number={1999}, journal={Microscopy of semiconducting materials 1999: Proceedings of the Institute of Physics conference held at Oxford University, 22-25 March, 1999}, publisher={Philadelphia, Pa.: Institute of Physics Publishing}, author={Elliott S.L., Broom R.F. and Humphreys C.J., Thrush E.J. and Considine L., Thomson D.B. and W.B., De Boer}, editor={Cullis, A.G. and Beanland, R.Editors}, year={1999}, pages={727–730} }
 @article{hanser_nam_bremser_thomson_gehrke_zheleva_davis_1999, title={Growth, doping and characterization of epitaxial thin films and patterned structures of AlN, GaN, and AlxGa1-xN}, volume={8}, ISSN={["1879-0062"]}, DOI={10.1016/S0925-9635(98)00341-0}, abstractNote={Abstract Advancements in the doping of GaN and AlxGa1−xN thin films, and the growth of GaN and AlxGa1−xN structures on patterned heterostructure substrates via metalorganic vapor phase epitaxy are reported. The acceptor-type behavior of Mg-doped GaN films grown in N2 diluents is presented. Net ionized impurity concentrations up to 8×1018 cm−3 and Hall mobilities up to ≈14 cm2 V−1 s−1 were measured for Mg-doped films grown in N2 in the as-grown condition. Donor and acceptor doping of AlxGa1−xN alloys was performed. Acceptor doping of AlxGa1−xN for x≤0.13 and donor doping for x≤0.58 were achieved for films deposited at 1100 °C. Lateral epitaxial overgrowth of GaN and AlxGa1−xN layers was investigated. The growth and coalescence of GaN and AlxGa1−xN stripes patterned in SiO2 and/or SiNx masks deposited on GaN, including aligned second lateral epitaxial overgrowth on initial laterally overgrown GaN layers, are discussed.}, number={2-5}, journal={DIAMOND AND RELATED MATERIALS}, author={Hanser, AD and Nam, OH and Bremser, MD and Thomson, DB and Gehrke, T and Zheleva, TS and Davis, RF}, year={1999}, month={Mar}, pages={288–294} }
 @article{pavlovska_torres_edwards_bauer_smith_doak_tsong_thomson_davis_1999, title={Homoepitaxial GaN layers studied by low-energy electron microscopy, atomic force microscopy and transmission electronmicroscopy}, volume={176}, number={1}, journal={Physica Status Solidi. A, Applications and Materials Science}, author={Pavlovska, A. and Torres, V. M. and Edwards, J. L. and Bauer, E. and Smith, D. J. and Doak, R. B. and Tsong, I. S. T. and Thomson, D. B. and Davis, R. F.}, year={1999}, pages={469–473} }
 @article{pavlovska_torres_bauer_doak_tsong_thomson_davis_1999, title={Low-energy electron microscopy observations of GaN homoepitaxy using a supersonic jet source}, volume={75}, ISSN={["0003-6951"]}, DOI={10.1063/1.124575}, abstractNote={A study of the homoepitaxial growth of GaN(0001) layers was conducted in situ and in real time using the low-energy electron microscope. The Ga flux was supplied by an evaporative cell while the NH3 flux was supplied via a seeded-beam supersonic jet source. At growth temperatures of 665 °C and 677 °C, smooth GaN(0001) layers with well-defined step structures were grown on GaN(0001) substrates prepared by metalorganic chemical vapor deposition. In general, nonfaceted homoepitaxial layers were achieved when the Ga/NH3 flux ratios exceeded 2, starting with a Ga-covered substrate surface, in the temperature range of 655–710 °C.}, number={7}, journal={APPLIED PHYSICS LETTERS}, author={Pavlovska, A and Torres, VM and Bauer, E and Doak, RB and Tsong, IST and Thomson, DB and Davis, RF}, year={1999}, month={Aug}, pages={989–991} }
 @article{kaminska_piotrowska_jasinski_kozubowski_barcz_golaszewska_thomson_davis_bremser_1999, title={Ni/Si-based contacts to GaN: Thermally activated structural transformations leading to ohmic behavior}, volume={4S1}, number={G9.9}, journal={MRS Internet Journal of Nitride Semiconductor Research}, author={Kaminska, E. and Piotrowska, A. and Jasinski, J. and Kozubowski, J. and Barcz, A. and Golaszewska, K. and Thomson, D. B. and Davis, R. F. and Bremser, M. D.}, year={1999} }
 @article{gehrke_linthicum_thomson_rajagopal_batchelor_davis_1999, title={Pendeo-epitaxy of gallium nitride and aluminum nitride films and heterostructures on silicon carbide substrate}, volume={4S1}, number={G3.2}, journal={MRS Internet Journal of Nitride Semiconductor Research}, author={Gehrke, T. and Linthicum, K. J. and Thomson, D. B. and Rajagopal, P. and Batchelor, A. D. and Davis, R. F.}, year={1999} }
 @article{linthicum_gehrke_thomson_carlson_rajagopal_smith_batchelor_davis_1999, title={Pendeo-epitaxy of gallium nitride thin films}, volume={75}, DOI={10.1063/1.124317}, abstractNote={Pendeoepitaxy, a form of selective lateral growth of GaN thin films has been developed using GaN/AlN/6H–SiC(0001) substrates and produced by organometallic vapor phase epitaxy. Selective lateral growth is forced to initiate from the (112̄0) GaN sidewalls of etched GaN seed forms by incorporating a silicon nitride seed mask and employing the SiC substrate as a pseudomask. Coalescence over and between the seed forms was achieved. Transmission electron microscopy revealed that all vertically threading defects stemming from the GaN/AlN and AlN/SiC interfaces are contained within the seed forms and a substantial reduction in the dislocation density of the laterally grown GaN. Atomic force microscopy analysis of the (112̄0) face of discrete pendeoepitaxial structures revealed a root mean square roughness of 0.98 Å. The pendeoepitaxial layer photoluminescence band edge emission peak was observed to be 3.454 eV and is blueshifted by 12 meV as compared to the GaN seed layer.}, number={2}, journal={Applied Physics Letters}, author={Linthicum, K. J. and Gehrke, T. and Thomson, D. B. and Carlson, E. P. and Rajagopal, P. and Smith, T. and Batchelor, D. and Davis, R.}, year={1999}, pages={196–198} }
 @misc{zheleva_smith_thomson_linthicum_rajagopal_davis_1999, title={Pendeo-epitaxy: A new approach for lateral growth of gallium nitride films}, volume={28}, number={4}, journal={Journal of Electronic Materials}, author={Zheleva, T. S. and Smith, S. A. and Thomson, D. B. and Linthicum, K. J. and Rajagopal, P. and Davis, R. F.}, year={1999}, pages={L5–8} }
 @article{zheleva_smith_thomson_gehrke_linthicum_rajagopal_carlson_ashmawi_davis_1999, title={Pendeo-epitaxy: A new approach for lateral growth of gallium nitride structures}, volume={4S1}, number={G3.38}, journal={MRS Internet Journal of Nitride Semiconductor Research}, author={Zheleva, T. S. and Smith, S. A. and Thomson, D. B. and Gehrke, T. and Linthicum, K. J. and Rajagopal, P. and Carlson, E. and Ashmawi, W. M. and Davis, R. F.}, year={1999} }
 @article{linthicum_gehrke_thomson_tracy_carlson_smith_zheleva_zorman_mehregany_davis_1999, title={Process routes for low defect-density GaN on various substrates employing pendeo-epitaxial growth techniques}, volume={4S1}, number={G4.9}, journal={MRS Internet Journal of Nitride Semiconductor Research}, author={Linthicum, K. J. and Gehrke, T. and Thomson, D. B. and Tracy, K. M. and Carlson, E. P. and Smith, T. P. and Zheleva, T. S. and Zorman, C. A. and Mehregany, M. and Davis, R. F.}, year={1999} }
 @article{thomson_gehrke_linthicum_rajagopal_davis_1999, title={Ranges of deposition temperatures applicable for metalorganic vapor phase epitaxy of GaN films via the technique of pendeo- epitaxy}, volume={4S1}, number={G3.37}, journal={MRS Internet Journal of Nitride Semiconductor Research}, author={Thomson, D. B. and Gehrke, T. and Linthicum, K. J. and Rajagopal, P. and Davis, R. F.}, year={1999} }
 @article{danielsson_zetterling_ostling_breitholtz_linthicum_thomson_nam_davis_1999, title={Simulation and electrical characterization of GaN/SiC and AlGaN/SiC heterodiodes}, volume={61-2}, number={1999 July 30}, journal={Materials Science & Engineering. B, Solid-state Materials for Advanced Technology}, author={Danielsson, E. and Zetterling, C. M. and Ostling, M. and Breitholtz, B. and Linthicum, K. and Thomson, D. B. and Nam, O. H. and Davis, R. F.}, year={1999}, pages={320–324} }