Total-Ionizing-Dose Radiation Induced Gate Damage in High Voltage P-GaN Gate HEMTs

TID radiation induced damage in metal/p-GaN/AlGaN/GaN gate stack of p-GaN gate HEMTs is studied and the damage mechanisms highly correlated with electric field are revealed. For on-state bias, irradiation damages related to donor-like traps are located at the reverse-biased metal/p-GaN Schottky junction with high electric field. The depletion region in the Schottky junction would extend, and the trap-assisted tunneling mechanism could be introduced to increase the forward gate current. For off-state bias, irradiation damages are located at the reverse-biased p-GaN/AlGaN/GaN (p-i-n) junction in relation to holes trapped in the AlGaN barrier and the GaN channel. The energy barrier of the AlGaN barrier and the GaN channel would be lowered for electron injection, leading to reverse gate current and off-state drain leakage current increasing. Irradiation induced damage at the Schottky junction may be permanent, while the p-i-n junction damage is recoverable with time.