@article{stein_khachariya_mita_breckenridge_tweedie_reddy_sierakowski_kamler_bockowski_kohn_et al._2023, title={Schottky contacts on ultra-high-pressure-annealed GaN with high rectification ratio and near-unity ideality factor}, volume={16}, ISSN={["1882-0786"]}, DOI={10.35848/1882-0786/acc443}, abstractNote={Abstract We investigate the electrical characteristics of Ni Schottky contacts on n-type GaN films that have undergone ultra-high-pressure annealing (UHPA), a key processing step for activating implanted Mg. Contacts deposited on these films exhibit low rectification and high leakage current compared to contacts on as-grown films. By employing an optimized surface treatment to restore the GaN surface following UHPA, we obtain Schottky contacts with a high rectification ratio of ∼10 9 , a near-unity ideality factor of 1.03, and a barrier height of ∼0.9 eV. These characteristics enable the development of GaN junction barrier Schottky diodes employing Mg implantation and UHPA.}, number={3}, journal={APPLIED PHYSICS EXPRESS}, author={Stein, Shane R. and Khachariya, Dolar and Mita, Seiji and Breckenridge, M. Hayden and Tweedie, James and Reddy, Pramod and Sierakowski, Kacper and Kamler, Grzegorz and Bockowski, Michal and Kohn, Erhard and et al.}, year={2023}, month={Mar} }
 @article{stein_khachariya_pavlidis_2022, title={Design and performance analysis of GaN vertical JFETs with ion-implanted gates}, volume={37}, ISSN={["1361-6641"]}, DOI={10.1088/1361-6641/ac9d00}, abstractNote={Abstract We present a comprehensive performance analysis of vertical GaN JFETs via TCAD simulation with unique considerations for gates formed by Mg ion implantation into GaN. The dependence of the specific ON-resistance and pinch-off voltage on the gate and channel design parameters is first evaluated for a JFET with abrupt gate-channel junctions. Then, the influence of the gate acceptor concentration and distribution is studied to elucidate the consequences of incomplete acceptor activation or acceptor diffusion resulting from specialized post-implantation annealing techniques necessary for the activation of p-GaN. Examples of normally-ON and normally-OFF designs with 1.7 kV breakdown voltage for 1.2 kV applications are chosen for the activation and diffusion studies to demonstrate how the pinch-off and conduction characteristics are affected for different channel widths and doping concentrations conducive to each type of operation. Record low specific ON-resistance below 1 mΩ cm 2 is predicted for both, but gate acceptor diffusion increases the channel resistance, especially for JFETs designed to be normally-OFF.}, number={12}, journal={SEMICONDUCTOR SCIENCE AND TECHNOLOGY}, author={Stein, Shane R. and Khachariya, Dolar and Pavlidis, Spyridon}, year={2022}, month={Dec} }
 @article{khachariya_stein_mecouch_breckenridge_rathkanthiwar_mita_moody_reddy_tweedie_kirste_et al._2022, title={Vertical GaN junction barrier Schottky diodes with near-ideal performance using Mg implantation activated by ultra-high-pressure annealing}, volume={15}, ISSN={["1882-0786"]}, DOI={10.35848/1882-0786/ac8f81}, abstractNote={Abstract We report a kV class, low ON-resistance, vertical GaN junction barrier Schottky (JBS) diode with selective-area p-regions formed via Mg implantation followed by high-temperature, ultra-high pressure (UHP) post-implantation activation anneal. The JBS has an ideality factor of 1.03, a turn-on voltage of 0.75 V, and a specific differential ON-resistance of 0.6 mΩ·cm 2 . The breakdown voltage of the JBS diode is 915 V, corresponding to a maximum electric field of 3.3 MV cm −1 . These results underline that high-performance GaN JBS can be realized using Mg implantation and high-temperature UHP post-activation anneal.}, number={10}, journal={APPLIED PHYSICS EXPRESS}, author={Khachariya, Dolar and Stein, Shane and Mecouch, Will and Breckenridge, M. Hayden and Rathkanthiwar, Shashwat and Mita, Seiji and Moody, Baxter and Reddy, Pramod and Tweedie, James and Kirste, Ronny and et al.}, year={2022}, month={Oct} }
 @article{stein_robbins_reddy_collazo_pavlidis_2021, title={UV illumination effects on AlGaN/GaN HEMTs for tunable RF oscillators}, ISSN={["2164-2958"]}, DOI={10.1109/RWS50353.2021.9360392}, abstractNote={We present the first investigation of AlGaN/GaN HEMTs as optically-controlled microwave semiconductor devices for use in next-generation, high-power microwave photonics systems. Measurements show a modest change in S21 in the presence of UV illumination that induces internal photoconductive and photovoltaic effects. This contrasts with the significant shift in the measured gate capacitance, which can be used to tune future oscillators. This is investigated through the design of a 2.4 GHz Pierce oscillator with an optical tuning range of 3 MHz.}, journal={2021 IEEE RADIO AND WIRELESS SYMPOSIUM (RWS)}, author={Stein, Shane and Robbins, Max and Reddy, Pramod and Collazo, Ramon and Pavlidis, Spyridon}, year={2021}, pages={168–170} }