Electrical-stress-induced degradation in AlGaN/GaN high electron mobility transistors grown under gallium-rich, nitrogen-rich, and ammonia-rich conditions

We have evaluated the long-term electrical reliability of GaN/AlGaN high-electron-mobility transistors grown under Ga-rich, N-rich, and NH3-rich conditions. Vpinch-off shifts positively after stress for devices grown under Ga-rich and N-rich conditions, while it shifts negatively for NH3-rich devices. Density functional theory calculations suggest that the hot-electron-induced release of hydrogen from hydrogenated Ga-vacancies is primarily responsible for the degradation of devices grown in Ga-rich and N-rich conditions, while hydrogenated N-antisites are the dominant defects causing degradation in devices grown under NH3-rich conditions.