Investigation of Temperature-Dependent Gate Degradation in Normally-Off AlGaN/GaN High-Electron-Mobility Transistor p-GaN

The effect of temperature on gate degradation behavior was analyzed in Schottky-type p-GaN gate HEMTs under a positive gate voltage. TDDB measurements were conducted at various temperatures, revealing an accelerated gate failure rate at lower temperatures. A Weibull distribution analysis was employed to predict the 10-year rated gate voltage, showing that the rated voltage at −10 °C is significantly lower than at 60 °C. Furthermore, the derived activation energy of −0.22 eV indicates that gate degradation intensifies in colder environments. Hole accumulation occurring at the p-GaN/AlGaN interface can promote degradation by facilitating electron injection and accelerating defect generation in the presence of strong electric fields. At higher temperatures, hole release mitigates charge accumulation, thereby extending device longevity. These findings highlight the necessity of reliability assessments for p-GaN gate HEMTs suitable for environments with low temperatures, including space and polar environments.