5 May 2010 GaN-based high-temperature and radiation-hard electronics for harsh environments
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We develop novel GaN-based high temperature and radiation-hard electronics to realize data acquisition electronics and transmitters suitable for operations in harsh planetary environments. In this paper, we discuss our research on AlGaN/GaN metal-oxide-semiconductor (MOS) transistors that are targeted for 500 °C operation and >2 Mrad radiation hardness. For the target device performance, we develop Schottky-free AlGaN/GaN MOS transistors, where a gate electrode is processed in a MOS layout using an Al2O3 gate dielectric layer. The AlGaN/GaN MOS transistors fabricated with the wide-bandgap gate oxide layer enable Schottky-free gate electrodes, resulting in a much reduced gate leakage current and an improved sub-threshold current than the current AlGaN/GaN field effect transistors. In this study, characterization of our AlGaN/GaN MOS transistors is carried out over the temperature range of 25°C to 500°C. The Ids- Vgs and Ids-Vds curves measured as a function of temperature show an excellent pinch-off behavior up to 450°C. Off-state degradation is not observed up to 400 °C, but it becomes measurable at 450 °C. The off-state current is increased at 500 °C due to the gate leakage current, and the AlGaN/GaN MOS HEMT does not get pinched-off completely. Radiation hardness testing of the AlGaN/GaN MOS transistors is performed using a 50 MeV 60Co gamma source to explore effects of TID (total ion dose). Excellent Ids-Vgs and Ids-Vds characteristics are measured even after exposures to a TID of 2Mrad. A slight decrease of saturation current (ΔIdss~3 mA/mm) is observed due to the 2Mrad irradiation.
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Kyung-Ah Son, Anna Liao, Gerald Lung, Manuel Gallegos, Toshiro Hatake, Richard D. Harris, Leif Z. Scheick, William D. Smythe, "GaN-based high-temperature and radiation-hard electronics for harsh environments", Proc. SPIE 7679, Micro- and Nanotechnology Sensors, Systems, and Applications II, 76790U (5 May 2010); doi: 10.1117/12.852711; https://doi.org/10.1117/12.852711

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