Time-Dependent Breakdown in Schottky p-GaN Gate HEMTs Under Dynamic Gate Stress

This article presents a comprehensive investigation of the time-dependent gate breakdown (TDGB) behavior in Schottky p-GaN gate high-electron mobility transistors (HEMTs) under dynamic gate stress (DGS). Experiments are carried out over a wide frequency range (10 kHz–1 MHz) and temperature interval ($30~^{\circ }$C–$150~^{\circ }$C). In addition to analyzing the impact of the positive gate voltage level (V${}_{\text {GSH}}\text {)}$, the influence of the negative gate voltage level (V${}_{\text {GSL}}\text {)}$, applied during the device turn-off phase, is also investigated. This analysis provides guidelines for defining gate-drive conditions that minimize the risk of TDGB and offers physics-based insight into the underlying degradation mechanisms. For temperatures above$60~^{\circ }$C, the equivalent time-to-failure (ETTF) exhibits a nonmonotonic dependence on switching frequency, attributed to two distinct degradation mechanisms.Mechanism A, dominant at relatively low frequencies, is associated with the time-dependent defect generation duringon-state semiperiods.Mechanism B, prevailing at higher frequencies, arises from electrostatic potential transients occurring in the semifloating p-GaN layer duringoff-to-ontransitions. The value of VGSLmodulatesMechanism B, affecting ETTF at high frequency and temperature. A temperature-dependent analysis reveals that the stronger thermal activation ofMechanism Ashifts the transition between the two regimes toward higher frequencies as temperature decreases, eventually suppressing the contribution ofMechanism Bto TDGB at room temperature within the explored frequency range.