Time- and Temperature-dependent Degradation of p-GaN Gate HEMTs under Forward Gate Voltage Stress

In this study, we conducted an analysis of time-dependent degradation by applying forward gate bias in AlGaN/GaN high electron mobility transistors (HEMTs) with p-GaN gate. The temperature-dependent breakdown voltage was extracted through step voltage stress with different temperatures. To assess the lifetime of the device, constant voltage stress was performed with varying stress voltages and temperatures. The mean-time-to- failure (MTTF) and activation energy (Ea) was extracted from Weibull plot and Arrhenius plot, respectively. P-GaN gate HEMTs have a negative activation energy and a positive temperature dependence on time-to-failure and breakdown voltage. This temperature dependence suggests that the degradation under forward gate bias is related to hot carriers generated by high electric field in the reverse-biased Schottky junction.