@article{jur_wheeler_lichtenwalner_maria_johnson_2011, title={Epitaxial growth of lanthanide oxides La2O3 and Sc2O3 on GaN}, volume={98}, ISSN={["0003-6951"]}, DOI={10.1063/1.3541883}, abstractNote={Deposition of lanthanide oxides on GaN is investigated as a means to produce stable dielectric with good interface quality. Epitaxial growth of cubic ⟨111⟩-oriented Sc2O3 is observed on GaN [0001] with a lattice mismatch of 7.2%, whereas La2O3 growth, with a lattice mismatch of ∼21%, results in a mixed phase epitaxial film comprised of the bixbyite and hexagonal allotropes. Substantial roughening accompanies this mixed phase film. By inserting a thin Sc2O3 interfacial layer between La2O3 and GaN and a Sc2O3 capping layer, the crystal quality of the predominantly La2O3 layer is improved and the stack is stabilized against hydroxide formation under ambient conditions.}, number={4}, journal={APPLIED PHYSICS LETTERS}, author={Jur, Jesse S. and Wheeler, Virginia D. and Lichtenwalner, Daniel J. and Maria, Jon-Paul and Johnson, Mark A. L.}, year={2011}, month={Jan} }
 @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={AbstractInGaN/GaN quantum wells (QWs) grown at identical conditions on m‐plane GaN and c‐plane sapphire substrates were characterized by several techniques, aiming to clarify the reason for different emission wavelengths often observed in similar LED structures with m‐ and c‐plane surface orientations. Cathodoluminescence (CL) spectra of m‐plane QWs revealed shorter wavelength and no blueshift with increasing CL probe current in accordance with previous reports. Relative indium compositions were estimated by high‐resolution X‐ray diffraction to be 5.1 and 13.9% for m‐plane and c‐plane QWs, respectively. Cross‐sectional transmission electron microscopy images revealed that the well widths of the m‐plane QWs were noticeably thicker than those of the c‐plane QWs. The lower indium compositions and thicker well widths of the m‐plane QWs indicated that different indium incorporation and diffusion occurred in the structures grown on the GaN substrate, which is attributed to its surface off‐cut toward [0001] and the higher thermal conductivity with respect to that of sapphire.}, 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{park_ozbek_ma_veety_morgensen_barlage_wheeler_johnson_2010, title={An analytical model of source injection for N-type enhancement mode GaN-based Schottky Source/Drain MOSFET's with experimental demonstration}, volume={54}, ISSN={["0038-1101"]}, DOI={10.1016/j.sse.2010.06.013}, abstractNote={Abstract This study investigates the effect of the Gate-to-Source/Drain overlap structure of a GaN Schottky Source/Drain MOSFET. The Gate-to-Source overlap structure of the device allows the gate electric field to reduce the height of the Nickel(source)–GaN Schottky barrier near the SiO 2 –GaN interface at the source side, injecting more thermionically generated carriers over the partially reduced Schottky barrier. Based on this Schottky barrier lowering mechanism, an analytical model was developed. The analytical model shows that the reduction of the Schottky barrier height by 0.25 eV increases the on-state drain current by two orders of magnitude, which is in agreement of the previously reported TCAD simulation result in [6] . A specifically designed GaN Schottky Source/Drain MOSFET with the Gate-to-Source/Drain overlap structure was fabricated and characterized; the I D – V DS characteristic of the device shows that the on-state drain current of the device was increased by up to 160× compared to the same kind of device without the overlap structure (reported in Lei Ma (2007) [7] ), which is in agreement with the analytical model described herein.}, number={12}, journal={SOLID-STATE ELECTRONICS}, author={Park, Jaehoon and Ozbek, Ayse M. and Ma, Lei and Veety, Matthew T. and Morgensen, Michael P. and Barlage, Douglas W. and Wheeler, Virginia D. and Johnson, Mark A. L.}, year={2010}, month={Dec}, pages={1680–1685} }
 @article{lai_paskova_wheeler_grenko_johnson_udwary_preble_evans_2010, title={Effect of m-plane GaN substrate miscut on InGaN/GaN quantum well growth}, volume={312}, ISSN={["1873-5002"]}, DOI={10.1016/j.jcrysgro.2010.01.020}, abstractNote={The effect of m-plane GaN substrate miscut on the growth of InGaN/GaN quantum wells (QWs) was investigated. It was found that the miscut toward [0 0 0 1] c+-axis resulted in an increase of In incorporation efficiency and in a green-shift of the QW emission, while the miscut toward [1 1 2 0] a-axis resulted in even higher In compositions but it also led to an increased epitaxial surface roughness and deterioration of the QW structures. The results indicated that miscut toward a-axis is undesirable while miscut toward c+-axis is beneficial for achieving longer wavelength emission in QWs grown on m-plane GaN substrates.}, number={7}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Lai, K. Y. and Paskova, T. and Wheeler, V. D. and Grenko, J. A. and Johnson, M. A. L. and Udwary, K. and Preble, E. A. and Evans, K. R.}, year={2010}, month={Mar}, pages={902–905} }
 @article{lai_paskova_wheeler_grenko_johnson_barlage_udwary_preble_evans_2009, title={Excitation current dependent cathodoluminescence study of InGaN/GaN quantum wells grown on m-plane and c-plane GaN substrates}, volume={106}, ISSN={["1089-7550"]}, DOI={10.1063/1.3264729}, abstractNote={InGaN/GaN quantum wells (QWs) grown with identical conditions on m-plane and c-plane GaN substrates were studied by cathodoluminescence spectroscopy. At a low current of 10 nA, the emission intensity and wavelength of the m-plane aligned QWs were found to be about two times stronger and 19.5 nm blueshifted with respect to that of the c-plane aligned QWs. An increase in the current over three orders of magnitude was found to result in an increase in the emission intensities, with faster saturation in the m-plane aligned QWs. This was explained by the screening of quantum-confined Stark effect in the emission efficiency of the c-plane aligned QWs.}, number={11}, journal={JOURNAL OF APPLIED PHYSICS}, author={Lai, K. Y. and Paskova, T. and Wheeler, V. D. and Grenko, J. A. and Johnson, M. A. L. and Barlage, D. W. and Udwary, K. and Preble, E. A. and Evans, K. R.}, year={2009}, month={Dec} }