@article{lai_paskova_wheeler_chung_grenko_johnson_udwary_preble_evans_2012, title={Indium incorporation in InGaN/GaN quantum wells grown on m-plane GaN substrate and c-plane sapphire}, volume={209}, ISSN={["1862-6319"]}, DOI={10.1002/pssa.201127345}, abstractNote={Abstract}, number={3}, journal={PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE}, author={Lai, K. Y. and Paskova, T. and Wheeler, V. D. and Chung, T. Y. and Grenko, J. A. and Johnson, M. A. L. and Udwary, K. and Preble, E. A. and Evans, K. R.}, year={2012}, month={Mar}, pages={559–564} }
 @article{mion_muth_preble_hanser_2006, title={Accurate dependence of gallium nitride thermal conductivity on dislocation density}, volume={89}, ISSN={["1077-3118"]}, DOI={10.1063/1.2335972}, abstractNote={The authors experimentally find that the thermal conductivity of gallium nitride depends critically on dislocation density using the 3-omega technique. For GaN with dislocation densities lower than 106cm−2, the thermal conductivity is independent with dislocation density. The thermal conductivity decreases with a logarithmic dependence for material with dislocation densities in the range of 107–1010cm−2. These results are in agreement with theoretical predictions. This study indicates that the hydride vapor phase epitaxy method offers an attractive route for the formation of semi-insulating gallium nitride with optimal thermal conductivity values around 230W∕mK and very low dislocation density near 5×104cm−2.}, number={9}, journal={APPLIED PHYSICS LETTERS}, author={Mion, C. and Muth, J. F. and Preble, E. A. and Hanser, D.}, year={2006}, month={Aug} }
 @article{zakharov_liliental-weber_wagner_reitmeier_preble_davis_2005, title={Structural TEM study of nonpolar a-plane gallium nitride grown on (1120) 4H-SiC by organometallic vapor phase epitaxy}, volume={71}, number={23}, journal={Physical Review. B, Condensed Matter and Materials Physics}, author={Zakharov, D. N. and Liliental-Weber, Z. and Wagner, B. and Reitmeier, Z. J. and Preble, E. A. and Davis, R. F.}, year={2005} }
 @inbook{bishop_preble_hallin_henry_storasta_jacobson_wagner_reitmeier_janzen_davis_2004, title={Growth of homoepitaxial films on 4H-SiC(1120) and 8 degrees off-axis 4H-SiC(0001) substrates and their characterization}, volume={457-460}, booktitle={Silicon carbide and related materials 2003: ICSCRM2003: Proceedings of the 10th International Conference on Silicon Carbide and Related Materials 2003, Lyon, France, October 5-10, 2003}, publisher={Utikon-Zurich, Switzerland: Trans Tech Publications}, author={Bishop, S. M. and Preble, E. A. and Hallin, C. and Henry, A. and Storasta, L. and Jacobson, H. and Wagner, B. P. and Reitmeier, Z. and Janzen, E. and Davis, R. F.}, editor={R. Madar, J. Camassel and Blanquet, E.Editors}, year={2004}, pages={221–224} }
 @article{preble_miraglia_roskowski_vetter_dudley_davis_2003, title={Domain structures in 6H-SiC wafers and their effect on the microstructures of GaN films grown on AlN and Al0.2Ga0.8N buffer layers}, volume={258}, ISSN={["0022-0248"]}, DOI={10.1016/S0022-0248(03)01515-X}, abstractNote={Silicon carbide wafers contain domains with varying sizes and degrees of tilt. The present research has shown that this microstructure is mimicked in GaN films deposited on AlN-containing buffer layers and that it masks most variations in the FWHM of the X-ray rocking curves of the former. The shape and FWHM in the GaN curves are determined both by domain tilting and dislocation broadening; the latter was dominant in areas of reduced tilt. Analyses of the on- and off-axis X-ray data acquired from these regions of lower tilt revealed the marked effect of the higher density of edge dislocations on broadening. This effect decreased with increasing GaN thickness due to dislocation annihilation. The densities of edge dislocations in GaN films deposited at 1010°C on pitted, less pitted and very smooth AlN layers of the same thickness grown at 1010°C, 1130°C and 1220°C, respectively, were lowest and highest in those films grown on the last two respective layers. Additional studies showed that GaN films grow on Al0.2Ga0.8N layers via step-flow and possess a lower edge dislocation density than films grown via the Stranski–Krastanov mode on AlN because of the reduced misfit and the absence of boundaries between coalesced islands.}, number={1-2}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Preble, EA and Miraglia, PQ and Roskowski, AM and Vetter, WM and Dudley, M and Davis, RF}, year={2003}, month={Oct}, pages={75–83} }
 @article{miraglia_preble_roskowski_einfeldt_davis_2003, title={Helical-type surface defects in GaN thin films epitaxially grown on GaN templates at reduced temperatures}, volume={253}, ISSN={["1873-5002"]}, DOI={10.1016/S0022-0248(03)00970-9}, abstractNote={Surface pits in the form of v-shaped defects and resulting surface roughening, previously associated solely with InGaN films, were observed and investigated using atomic force microscopy on GaN films grown at 780°C via metalorganic vapor phase epitaxy on conventionally and pendeo-epitaxially deposited GaN thin film templates. The density of the v-shaped defects was similar to the density of threading dislocations of ∼3×109 cm−2 (that originate from the heteroepitaxial interface between the GaN template layer and the SiC substrate). Moreover, the v-defect density was diminished with decreases in the dislocation density via increases in the template layer thickness or the use of pendeo-epitaxial seed layers. A concomitant reduction in the full-width half-maxima of the X-ray rocking curves was also observed. A qualitative model is presented that describes the formation of v-shaped defects as a result of interactions between the movement of surface steps, screw-type dislocation cores, and clusters of atoms on the terraces that form under conditions of high surface undercooling.}, number={1-4}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Miraglia, PQ and Preble, EA and Roskowski, AM and Einfeldt, S and Davis, RF}, year={2003}, month={Jun}, pages={16–25} }
 @article{miraglia_preble_roskowski_einfeldt_lim_liliental-weber_davis_2003, title={Helical-type surface defects in InGaN thin films epitaxially grown on GaN templates at reduced temperatures}, volume={437}, ISSN={["1879-2731"]}, DOI={10.1016/S0040-6090(03)00611-4}, abstractNote={Abstract The surface morphologies of InGaN films grown at 780 °C by metalorganic vapor phase epitaxy were determined using atomic force microscopy. A qualitative model was developed to explain the observed instabilities in the step morphology of these films, namely, the formation of hillocks and v-defects that give rise to surface roughening. V-defects, observed at a surface density greater than 2×10 8 /cm 2 , are a result of interactions between moving surface steps, cores of screw-type dislocations, and two-dimensional islands of atoms that form on the terraces during growth at high surface undercooling. A delay in the formation of v-defects in InGaN to a nominal thickness of 10 nm was observed and associated with the ammonia partial pressure and the interactions between steps associated with hillock islands and cores of screw-type dislocations. Hillock formation was attributed to a transition in the thermodynamic mode of film growth, as three-dimensional islands nucleated on the cores of screw-type dislocations at a density of 2×10 8 /cm 2 . Explanations for the foregoing observations are based on growth model theory previously developed by Burton, Cabrera and Frank and on changes in the surface kinetics with temperature, In composition, and gas phase composition.}, number={1-2}, journal={THIN SOLID FILMS}, author={Miraglia, PQ and Preble, EA and Roskowski, AM and Einfeldt, S and Lim, SH and Liliental-Weber, Z and Davis, RF}, year={2003}, month={Aug}, pages={140–149} }
 @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{preble_mclean_kiesel_miraglia_albrecht_davis_2002, title={Application of Nomarski interference contrast microscopy as a thickness monitor in the preparation of transparent, SiG-based, cross-sectional TEM samples}, volume={92}, ISSN={["0304-3991"]}, DOI={10.1016/S0304-3991(02)00142-0}, abstractNote={Reflected light optical microscopy using a Nomarski prism and a differential interference contrast filter have been employed in concert to achieve a technique that provides an accurate color reference for thickness during the dimpling and ion milling of transparent transmission electron microscopy samples of 6H-SiC(000 1) wafers. The samples had thin films of AIN, GaN, and Au deposited on the SiC substrate. A sequence of variously colored primary and secondary interference bands was observed when the SiC was thinner than 20 microm using an optical microscope. The color bands were correlated with the TEM sample thickness as measured via scanning electron microscopy. The interference contrast was used to provide an indication of the dimpling rate, the ion milling rate, and also the most probable location of perforation, which are useful to reduce sample breakage. The application of pressure during the initial cross-sectional preparation reduced the separation of the two halves of the sample sandwich and resulted in increased shielding of the film surface from ion milling damage.}, number={3-4}, journal={ULTRAMICROSCOPY}, author={Preble, EA and McLean, HA and Kiesel, SM and Miraglia, P and Albrecht, M and Davis, RF}, year={2002}, month={Aug}, pages={265–271} }
 @article{preble_tracy_kiesel_mclean_miraglia_nemanich_davis_albrecht_smith_2002, title={Electrical, structural and microstructural characteristics of as-deposited and annealed Pt and Au contacts on chemical-vapor-cleaned GaN thin films}, volume={91}, ISSN={["0021-8979"]}, DOI={10.1063/1.1432127}, abstractNote={Schottky contacts of Pt(111) and Au(111) were deposited on chemical-vapor-cleaned, n-type GaN(0001) thin films. The growth mode of the deposition, as determined by x-ray photoelectron spectroscopy analysis, followed the two-dimensional Frank–van der Merwe growth model. The resulting as-deposited metal films were monocrystalline and epitaxial with a (111)//(0002) relationship with the GaN. Selected samples were annealed for three minutes at 400 °C, 600 °C or 800 °C. The rectifying behavior of both contacts degraded at 400 °C; they became ohmic after annealing at 600 °C (Au) or 800 °C (Pt). High-resolution transmission electron micrographs revealed reactions at the metal/GaN interfaces for the higher temperature samples. X-ray diffraction results revealed an unidentified phase in the Pt sample annealed at 800 °C. A decrease in the room temperature in-plane (111) lattice constant for both metals, ranging from −0.1% to −0.5%, was observed as the annealing temperature was increased from 400 to 800 °C. This plastic deformation was caused by tensile stresses along the [111] direction that exceeded the yield strength as a result of the large differences in the coefficients of thermal expansion between the metal contacts and the GaN film.}, number={4}, journal={JOURNAL OF APPLIED PHYSICS}, author={Preble, EA and Tracy, KM and Kiesel, S and McLean, H and Miraglia, PQ and Nemanich, RJ and Davis, RF and Albrecht, M and Smith, DJ}, year={2002}, month={Feb}, pages={2133–2137} }
 @article{davis_roskowski_preble_speck_heying_freitas_glaser_carlos_2002, title={Gallium nitride materials - Progress, status, and potential roadblocks}, volume={90}, ISSN={["1558-2256"]}, DOI={10.1109/JPROC.2002.1021564}, abstractNote={Metal-organic vapor phase epitaxy (MOVPE) and molecular beam epitaxy (MBE) are the principal techniques for the growth and n-type (Si) and p-type (Mg) doping of III-nitride thin films on sapphire and silicon carbide substrates as well as previously grown GaN films. Lateral and pendeoepitaxy via MOVPE reduce significantly the dislocation density and residual strain in GaN and AlGaN films. However tilt and coalescence boundaries are produced in the laterally growing material. Very high electron mobilities in the nitrides have been realized in radio-frequency plasma-assisted MBE GaN films and in two-dimensional electron gases in the AlGaN/GaN system grown on MOVPE-derived GaN substrates at the crossover from the intermediate growth regime to the droplet regime. State-of-the-art Mg doping profiles and transport properties have been achieved in MBE-derived p-type GaN. The Mg-memory effect, and heterogeneous growth, substrate uniformity, and flux control are significant challenges for MOVPE and MBE, respectively. Photoluminescence (PL) of MOVPE-derived unintentionally doped (UID) heteroepitaxial GaN films show sharp lines near 3.478 eV due to recombination processes associated with the annihilation of free-excitons (FEs) and excitons bound to a neutral shallow donor (D/spl deg/X).}, number={6}, journal={PROCEEDINGS OF THE IEEE}, author={Davis, RF and Roskowski, AM and Preble, EA and Speck, JS and Heying, B and Freitas, JA and Glaser, ER and Carlos, WE}, year={2002}, month={Jun}, pages={993–1005} }
 @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{roskowski_preble_einfeldt_miraglia_davis_2002, title={Investigations regarding the maskless pendeo-epitaxial growth of GaN films prior to coalescence}, volume={38}, ISSN={["0018-9197"]}, DOI={10.1109/JQE.2002.801005}, abstractNote={Pendeo-epitaxy employs lateral growth from etched seed forms to achieve a marked reduction in dislocation density in a material. In this research, high-resolution X-ray diffraction and atomic force microscopy of GaN stripes and the laterally grown wings confirmed transmission electron microscopy results regarding the reduction in dislocations in the latter regions. Micro-Raman and X-ray diffraction measurements showed the wings to be tilted /spl les/0.15/spl deg/ due to tensile stresses in the stripes induced primarily by the mismatch in the coefficients of thermal expansion between the GaN stripe and the SiC substrate. A strong, low-temperature D/spl deg/X peak at /spl ap/3.466 eV with a FWHM of /spl les/300 /spl mu/eV was measured in the wing material by micro-photoluminescence. Films grown at 1020/spl deg/C exhibited similar vertical [0001] and lateral [112~0] growth rates. Increasing the growth temperature increased the latter due to the higher thermal stability of the (112~0) GaN and initiated growth of spiral hillocks on the (0001) surface of the stripes. The latter were due to adatom diffusion to heterogeneous steps previously nucleated at the intersections of pure screw or mixed dislocations. The (112~0) surface was atomically smooth under all growth conditions with a root mean square roughness value of 0.17 nm.}, number={8}, journal={IEEE JOURNAL OF QUANTUM ELECTRONICS}, author={Roskowski, AM and Preble, EA and Einfeldt, S and Miraglia, PM and Davis, RF}, year={2002}, month={Aug}, pages={1006–1016} }
 @article{roskowski_preble_einfeldt_miraglia_davis_2002, title={Maskless pendeo-epitaxial growth of GaN films}, volume={31}, ISSN={["1543-186X"]}, DOI={10.1007/s11664-002-0095-6}, number={5}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Roskowski, AM and Preble, EA and Einfeldt, S and Miraglia, PM and Davis, RF}, year={2002}, month={May}, pages={421–428} }
 @article{roskowski_preble_einfeldt_miraglia_schuck_grober_davis_2002, title={Reduction in dislocation density and strain in GaN thin films grown via maskless pendeo-epitaxy}, volume={10}, number={4}, journal={Opto-electronics Review}, author={Roskowski, A. M. and Preble, E. A. and Einfeldt, S. and Miraglia, P. M. and Schuck, J. and Grober, R. and Davis, R. F.}, year={2002}, pages={261–270} }
 @article{einfeldt_roskowski_preble_davis_2002, title={Strain and crystallographic tilt in uncoalesced GaN layers grown by maskless pendeoepitaxy}, volume={80}, ISSN={["0003-6951"]}, DOI={10.1063/1.1448145}, abstractNote={The strain in thin GaN layers grown by maskless pendeoepitaxy has been investigated using high-resolution x-ray diffraction and finite-element simulations. The crystallographic tilt of the free-hanging wings was determined to result from the strain relaxation of the seed stripes along [0001]. The impact of the dimensions of the pendeostructure and of the formation of crystal defects on the expected wing tilt is discussed.}, number={6}, journal={APPLIED PHYSICS LETTERS}, author={Einfeldt, S and Roskowski, AM and Preble, EA and Davis, RF}, year={2002}, month={Feb}, pages={953–955} }
 @article{roskowski_miraglia_preble_einfeldt_davis_2002, title={Surface instability and associated roughness during conventional and pendeo-epitaxial growth of GaN(0001) films via MOVPE}, volume={241}, ISSN={["0022-0248"]}, DOI={10.1016/S0022-0248(02)00943-0}, abstractNote={Investigations of the origins of surface roughening in GaN(0 0 0 1) have resulted in the development of a growth process route having an optimum temperature of 1020°C and a film thickness beyond 2.5 μm which results in films with the smoothest surface morphology. Atomic force microscopy (AFM) revealed uncoalesced GaN islands and hillocks for non-optimum temperatures below and above 1020°C, respectively. Uncoalesced islands were a result of insufficient lateral growth. Hillocks were a result of the rotation of heterogeneous steps formed at pure screw or mixed dislocations which terminated on the (0 0 0 1) surface. Growth of the latter features was controlled kinetically by temperature through adatom diffusion. The 106 cm−2 density of hillocks was reduced through growth on thick GaN templates and regions of pendeo-epitaxy (PE) overgrowth with lower pure screw or mixed dislocations. Smooth PE surfaces were obtained at temperatures that reduced the lateral to vertical growth rate but also retarded hillock growth that originated in the stripe regions. The (112̄0) PE sidewall surface was atomically smooth, with a root mean square roughness value of 0.17 nm, which was the noise limited resolution of the AFM measurements.}, number={1-2}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Roskowski, AM and Miraglia, PQ and Preble, EA and Einfeldt, S and Davis, RF}, year={2002}, month={May}, pages={141–150} }
 @article{davis_gehrke_linthicum_preble_rajagopal_ronning_zorman_mehregany_2001, title={Conventional and pendeo-epitaxial growth of GaN(0001) thin films on Si(111) substrates}, volume={231}, ISSN={["1873-5002"]}, DOI={10.1016/S0022-0248(01)01462-2}, abstractNote={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.}, number={3}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Davis, RF and Gehrke, T and Linthicum, KJ and Preble, E and Rajagopal, P and Ronning, C and Zorman, C and Mehregany, M}, year={2001}, month={Oct}, pages={335–341} }
 @article{davis_gehrke_linthicum_zheleva_preble_rajagopal_zorman_mehregany_2001, title={Pendeo-epitaxial growth of thin films of gallium nitride and related materials and their characterization}, volume={225}, ISSN={["0022-0248"]}, DOI={10.1016/S0022-0248(01)00836-3}, abstractNote={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.}, number={2-4}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Davis, RF and Gehrke, T and Linthicum, KJ and Zheleva, TS and Preble, EA and Rajagopal, P and Zorman, CA and Mehregany, M}, year={2001}, month={May}, pages={134–140} }
 @article{davis_gehrke_linthicum_rajagopal_roskowski_zheleva_preble_zorman_mehregany_schwarz_et al._2001, title={Review of pendeo-epitaxial growth and characterization of thin films of GaN and AlGaN alloys on 6H-SiC(0001) and Si(111) substrates}, volume={6}, number={14}, journal={MRS Internet Journal of Nitride Semiconductor Research}, author={Davis, R. F. and Gehrke, T. and Linthicum, K. J. and Rajagopal, P. and Roskowski, A. M. and Zheleva, T. and Preble, E. A. and Zorman, C. A. and Mehregany, M. and Schwarz, U. and et al.}, year={2001}, pages={1–16} }
 @article{roskowski_miraglia_preble_einfeldt_stiles_davis_schuck_grober_schwarz_2001, title={Strain and dislocation reduction in maskless pendeo-epitaxy GaN thin films}, volume={188}, DOI={10.1002/1521-396x(200112)188:2<729::aid-pssa729>3.0.co;2-w}, abstractNote={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.}, number={2}, journal={Physica Status Solidi. A, Applications and Materials Science}, author={Roskowski, A. M. and Miraglia, P. Q. and Preble, E. A. and Einfeldt, S. and Stiles, T. and Davis, R. F. and Schuck, J. and Grober, R. and Schwarz, U.}, year={2001}, pages={729–732} }
 @article{gehrke_linthicum_preble_rajagopal_ronning_zorman_mehregany_davis_2000, title={Pendeo-epitaxial growth of gallium nitride on silicon substrates}, volume={29}, ISSN={["0361-5235"]}, DOI={10.1007/s11664-000-0068-6}, number={3}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Gehrke, T and Linthicum, KJ and Preble, E and Rajagopal, P and Ronning, C and Zorman, C and Mehregany, M and Davis, RF}, year={2000}, month={Mar}, pages={306–310} }
 @article{gehrke_linthicum_rajagopal_preble_carlson_robin_davis_2000, title={Pendeo-epitaxy (TM) process for aluminum gallium nitride thin films on silicon carbide substrates via metalorganic chemical vapor deposition}, volume={338}, number={3}, journal={Materials Science Forum}, author={Gehrke, T. and Linthicum, K. J. and Rajagopal, P. and Preble, E. A. and Carlson, E. P. and Robin, B. M. and Davis, R. F.}, year={2000}, pages={1491–1494} }
 @article{kang_zhirnov_wojak_preble_choi_hren_cuomo_1999, title={Investigation of thickness effects on AlN coated metal tips by in situ I-V measurement}, volume={17}, ISSN={["1071-1023"]}, DOI={10.1116/1.590608}, abstractNote={The effects of the aluminum nitride coating thickness on molybdenum emitter tips were investigated by an in situ I–V measurement technique inside a typical magnetron sputtering system. AlN was deposited on Mo tips using a dc-modulated 1 kW power source at 200 °C. Each I/V measurement was carried out immediately following a 15 s AlN deposition. Significantly improved field emission was observed as well as a strong emission thickness dependence, which we attribute to the influence of space charge.}, number={2}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B}, author={Kang, DH and Zhirnov, VV and Wojak, GJ and Preble, EA and Choi, WB and Hren, JJ and Cuomo, JJ}, year={1999}, pages={632–634} }