@misc{davis_nam_2003, title={Gallium nitride semiconductor structure including laterally offset patterned layers}, volume={6,608,327}, number={2003 Aug. 19}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Davis, R. F. and Nam, O.-H.}, year={2003} }
 @misc{davis_nam_zheleva_bremser_2003, title={Gallium nitride semiconductor structures including lateral gallium nitride layers}, volume={6,570,192}, number={2003 May 27}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Davis, R. F. and Nam, O.-H. and Zheleva, T. and Bremser, M. D.}, year={2003} }
 @misc{davis_nam_zheleva_bremser_2003, title={Methods of fabricating gallium nitride semiconductor layers by lateral overgrowth}, volume={6,602,763}, number={2003 Aug. 5}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Davis, R. F. and Nam, O.-H. and Zheleva, T. and Bremser, M. D.}, year={2003} }
 @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={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{zheleva_nam_ashmawi_griffin_davis_2001, title={Lateral epitaxy and dislocation density reduction in selectively grown GaN structures}, volume={222}, ISSN={["1873-5002"]}, DOI={10.1016/S0022-0248(00)00832-0}, abstractNote={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.}, number={4}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Zheleva, TS and Nam, OH and Ashmawi, WM and Griffin, JD and Davis, RF}, year={2001}, month={Feb}, pages={706–718} }
 @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} }
 @misc{davis_nam_zheleva_bremser_2000, title={Gallium nitride semiconductor structures including a lateral gallium nitride layer that extends from an underlying gallium nitride layer}, volume={6,051,849}, number={2000 Apr. 18}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Davis, R. F. and Nam, O.-H. and Zheleva, T. and Bremser, M. D.}, year={2000} }
 @article{davis_nam_zheleva_gehrke_linthicum_rajagopal_2000, title={Lateral- and pendeo-epitaxial growth and defect reduction in GaN thin films}, volume={338}, number={3}, journal={Materials Science Forum}, author={Davis, R. F. and Nam, O. H. and Zheleva, T. S. and Gehrke, T. and Linthicum, K. J. and Rajagopal, P.}, year={2000}, pages={1471–1476} }
 @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={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{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} }
 @article{zheleva_ashmawi_nam_davis_1999, title={Thermal mismatch stress relaxation via lateral epitaxy in selectively grown GaN structures}, volume={74}, ISSN={["0003-6951"]}, DOI={10.1063/1.123017}, abstractNote={A reduction in the dislocation density of 104–105 cm−2 has been achieved via lateral epitaxial overgrowth (LEO) of GaN films selectively grown from stripes etched in SiO2 masks deposited on GaN/AlN/6H–SiC(0001) heterostructures. The magnitudes and distribution of stresses generated in the LEO GaN layer and the SiO2, due primarily to differences in the coefficients of thermal expansion, were modeled using finite element (FE) analysis. These calculations showed that localized compressive stress fields of ≈3 GPa occurred at the edges of the LEO GaN in the vicinity of the GaN/SiO2 interface. Localized compression along the GaN substrate/SiO2 interface and tension along the 〈0001〉 direction were responsible for the change in shape of the SiO2 stripes from rectangular with flat sides to an airfoil shape with curved sides. The FE calculations also revealed that an increase in the width of the LEO GaN regions over the SiO2 or the reduction in the separation between the GaN stripes (all other dimensions being fixed) resulted in a slight reduction in the compressive stresses along the LEO GaN/SiO2 interface and an increase in the compressive stress along [0001]. An increase in the shear stress, at the corners of the LEO GaN near the LEO GaN/SiO2 interface, with an increase in the width of the LEO GaN region were also indicated.}, number={17}, journal={APPLIED PHYSICS LETTERS}, author={Zheleva, TS and Ashmawi, WM and Nam, OH and Davis, RF}, year={1999}, month={Apr}, pages={2492–2494} }
 @article{bremser_perry_nam_griffis_loesing_ricks_davis_1998, title={Acceptor and donor doping of AlxGa1-xN thin film alloys grown on 6H-SiC(0001) substrates via metalorganic vapor phase epitaxy}, volume={27}, ISSN={["0361-5235"]}, DOI={10.1007/s11664-998-0392-9}, number={4}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Bremser, MD and Perry, WG and Nam, OH and Griffis, DP and Loesing, R and Ricks, DA and Davis, RF}, year={1998}, month={Apr}, pages={229–232} }
 @article{ward_nam_hartman_english_mccarson_schlesser_sitar_davis_nemanich_1998, title={Electron emission characteristics of GaN pyramid arrays grown via organometallic vapor phase epitaxy}, volume={84}, ISSN={["0021-8979"]}, DOI={10.1063/1.368775}, abstractNote={Selective growth of arrays of silicon-doped GaN (Si:GaN) pyramids for field emitter applications has been achieved. The electron emission characteristics of these arrays has been measured using techniques such as field emission, field emission energy distribution analysis (FEED), photoemission electron microscopy (PEEM), and field emission electron microscopy (FEEM). The field emission current–voltage (I–V) results indicate an average threshold field as low as 7 V/μm for an emission current of 10 nA. It is suggested that the low threshold field value is a consequence of both the low work function of Si:GaN and the field enhancement of the pyramids. The results of the FEEM and FEED measurements indicate agreement with the field emission I–V characteristics. The FEED results indicate that the Si:GaN pyramids are conducting, and that no significant ohmic losses are present between the top contact to the array and the field emitting pyramids. The PEEM and FEEM images show that the emission from the arrays is uniform over a 150 μm field of view.}, number={9}, journal={JOURNAL OF APPLIED PHYSICS}, author={Ward, BL and Nam, OH and Hartman, JD and English, SL and McCarson, BL and Schlesser, R and Sitar, Z and Davis, RF and Nemanich, RJ}, year={1998}, month={Nov}, pages={5238–5242} }
 @article{nemanich_baumann_benjamin_nam_sowers_ward_ade_davis_1998, title={Electron emission properties of crystalline diamond and III-nitride surfaces}, volume={130}, ISSN={["0169-4332"]}, DOI={10.1016/s0169-4332(98)00140-8}, abstractNote={Wide bandgap semiconductors have the possibility of exhibiting a negative electron affinity (NEA) meaning that electrons in the conduction band are not bound by the surface. The surface conditions are shown to be of critical importance in obtaining a negative electron affinity. UV-photoelectron spectroscopy can be used to distinguish and explore the effect. Surface terminations of molecular adsorbates and metals are shown to induce an NEA on diamond. Furthermore, a NEA has been established for epitaxial AlN and AlGaN on 6H–SiC. Field emission measurements from flat surfaces of p-type diamond and AlN are similar, but it is shown that the mechanisms may be quite different. The measurements support the recent suggestions that field emission from p-type diamond originates from the valence band while for AlN on SiC, the field emission results indicate emission from the AlN conduction band. We also report PEEM (photo-electron emission microscopy) and FEEM (field electron emission microscopy) images of an array of nitride emitters.}, number={1998 June}, journal={APPLIED SURFACE SCIENCE}, author={Nemanich, RJ and Baumann, PK and Benjamin, MC and Nam, OH and Sowers, AT and Ward, BL and Ade, H and Davis, RF}, year={1998}, month={Jun}, pages={694–703} }
 @article{nam_zheleva_bremser_davis_1998, title={Lateral epitaxial overgrowth of GaN films on SiO2 areas via metalorganic vapor phase epitaxy}, volume={27}, ISSN={["0361-5235"]}, DOI={10.1007/s11664-998-0393-8}, number={4}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Nam, OH and Zheleva, TS and Bremser, MD and Davis, RF}, year={1998}, month={Apr}, pages={233–237} }
 @article{freitas_nam_zheleva_davis_1998, title={Optical and structural properties of lateral epitaxial overgrown GaN layers}, volume={190}, number={1998 June}, journal={Journal of Crystal Growth}, author={Freitas, J. A. and Nam, O. H. and Zheleva, T. S. and Davis, R. F.}, year={1998}, pages={92–96} }
 @article{freitas_nam_davis_saparin_obyden_1998, title={Optical characterization of lateral epitaxial overgrown GaN layers}, volume={72}, ISSN={["0003-6951"]}, DOI={10.1063/1.121517}, abstractNote={The optical properties of homoepitaxial GaN layers deposited by organometallic vapor phase epitaxy on stripe-patterned GaN films on 6H-SiC substrates have been investigated. Analysis of the spatially-resolved Raman scattering spectra indicate an improvement in material quality of the overgrown region. Room-temperature color cathodoluminescence imaging and low-temperature photoluminescence measurements indicate that a donor and an acceptor, different from those detected in the underlying GaN/AlN/SiC substrate, have been incorporated in the epitaxial layer. Detailed photoluminescence studies of the near-band-edge emission strongly suggest that Si is the additional donor detected in the homoepitaxial GaN layer. Its occurrence, along with that of an acceptor-related defect which is primarily found in the laterally overgrown region, is discussed.}, number={23}, journal={APPLIED PHYSICS LETTERS}, author={Freitas, JA and Nam, OH and Davis, RF and Saparin, GV and Obyden, SK}, year={1998}, month={Jun}, pages={2990–2992} }
 @misc{stutz_mack_bremser_nam_davis_look_1998, title={Photoelectrochemical capacitance-voltage measurements in GaN}, volume={27}, ISSN={["0361-5235"]}, DOI={10.1007/s11664-998-0182-4}, number={5}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Stutz, CE and Mack, M and Bremser, MD and Nam, OH and Davis, RF and Look, DC}, year={1998}, month={May}, pages={L26–L28} }
 @article{nam_bremser_ward_nemanich_davis_1997, title={Growth of GaN and Al0.2Ga0.8N on patterened substrates via organometallic vapor phase epitaxy}, volume={36}, ISSN={["0021-4922"]}, DOI={10.1143/JJAP.36.L532}, abstractNote={ 
   The selective growth of GaN and  Al0.2Ga0.8N has been achieved on stripe and circular patterned    GaN/AlN/6H-SiC(0001) multilayer substrates. Growth morphologies on the stripe patterns were a    function of the widths of the stripes and the flow rate of triethylgallium. No ridge growth was    observed along the top edges of the truncated stripe patterns. Smooth (0001) top facets formed on    stripes ≥5 µ m wide. Uniform hexagonal pyramid arrays of undoped GaN and Si-doped GaN    were successfully grown on 5 µ m circular patterns. Field emission measurements of a Si-doped    GaN hexagonal pyramid array exhibited a turn-on field of 25  V/µ m for an emission current of 10.8 nA at an anode-to-sample distance of 27 µ m. 
   }, number={5A}, journal={JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS}, author={Nam, OH and Bremser, MD and Ward, BL and Nemanich, RJ and Davis, RF}, year={1997}, month={May}, pages={L532–L535} }
 @article{bremser_perry_zheleva_edwards_nam_parikh_aspnes_davis_1997, title={Growth, doping and characterization of AlxGa1-xN thin film alloys on 6H-SiC(0001) substrates}, volume={6}, ISSN={["0925-9635"]}, DOI={10.1016/S0925-9635(96)00626-7}, abstractNote={Thin films of AlxGa1 − xN (0.05≤x≤0.96) having smooth surfaces were deposited directly on both vicinal and on-axis 6H-SiC(0001) substrates. Cross-sectional transmission electron microscopy of Al0.13Ga0.87N revealed stacking faults near the SiC/nitride alloy interface and numerous threading dislocations. Energy dispersive analysis, Auger electron spectroscopy (AES) and Rutherford backscattering were used to determine the compositions. These were paired with their respective cathodoluminescence (CL) near band-edge emission energies. A negative bowing parameter was determined. The CL emission energies were similar to the bandgap energies obtained by spectroscopic ellipsometry. Field emission AES of the initial growth of Al0.2Ga0.8N revealed an Al-rich layer near the interface. N-type (Si) doping was achieved for AlxGa1 − xN for 0.12≤x≤0.42.}, number={2-4}, journal={DIAMOND AND RELATED MATERIALS}, author={Bremser, MD and Perry, WG and Zheleva, T and Edwards, NV and Nam, OH and Parikh, N and Aspnes, DE and Davis, RF}, year={1997}, month={Mar}, pages={196–201} }
 @article{nam_bremser_zheleva_davis_1997, title={Lateral epitaxy of low defect density GaN layers via organometallic vapor phase epitaxy}, volume={71}, number={18}, journal={Applied Physics Letters}, author={Nam, O.-H. and Bremser, M. D. and Zheleva, T. S. and Davis, R. F.}, year={1997}, pages={2698–2640} }
 @article{edwards_yoo_bremser_weeks_nam_davis_liu_stall_horton_perkins_et al._1997, title={Variation of GaN valence bands with biaxial stress and quantification of residual stress}, volume={70}, ISSN={["0003-6951"]}, DOI={10.1063/1.119089}, abstractNote={Low-temperature reflectance data on epitaxial GaN thin-film samples covering the widest range of tensile and compressive stress (−3.8–3.5 kbar) thus far explicitly show the nonlinear behavior of the B–A and C–A splittings versus the energy of the A exciton. Lineshape ambiguities that hindered previous interpretations have been resolved with reciprocal-space analysis, allowing us to obtain band parameters such as ΔSO=17.0±1meV with increased confidence.}, number={15}, journal={APPLIED PHYSICS LETTERS}, author={Edwards, NV and Yoo, SD and Bremser, MD and Weeks, TW and Nam, OH and Davis, RF and Liu, H and Stall, RA and Horton, MN and Perkins, NR and et al.}, year={1997}, month={Apr}, pages={2001–2003} }