Robustness of GaN Gate Injection Transistors under Repetitive Surge Energy and Overvoltage

GaN HEMTs have no avalanche capability and withstand the surge energy through capacitive charging, which often causes significant voltage overshoot up to their catastrophic limit. While the single-event overvoltage failure has been recently studied for GaN HEMTs, it is still unclear on their robustness under repetitive overvoltage and surge-energy events. This work studies the robustness of the GaN gate injection transistor (GIT) under repetitive overvoltage events implemented at the device hard-switched turn-off. A clamped, inductive switching circuit with a 400 V dc bias and a controllable parasitic inductance are used to generate the overvoltage stress events with different overvoltage magnitude up to 1050 V (90% of the device destruction limit), different switching periods down to 0.33 ms, and different temperatures up to 150 °C. The electrical parameters were characterized and monitored between stress cycles. The 650-V, 31-A rated GITs show no failure or permanent degradation after 1-million overvoltage events at different switching periods, or elevated temperatures. These results suggest the great potential of GaN GITs for applications that demand stressful operating conditions such as electrical vehicle powertrains.