Evaluation of stress voltage on off-state time-dependent breakdown for GaN MIS-HEMT with SiNx gate dielectric**Project supported by the National Key Research and Development Program, China (Grant No. 2017YFB0402800), the Key Research and Development Program of Guangdong Province, China (Grant Nos. 2019B010128002 and 2020B010173001), the National Natural Science Foundation of China (Grant No. U1601210), the Natural Science Foundation of Guangdong Province,

Abstract

Stress voltages on time-dependent breakdown characteristics of GaN MIS-HEMTs during negative gate bias stress (with VGS < 0, VD = VS = 0) and off-state stress (VG < VTh, VDS > 0, VS = 0) are investigated. For negative bias stress, the breakdown time distribution (β) decreases with the increasing negative gate voltage, while β is larger for higher drain voltage at off-state stress. Two humps in the time-dependent gate leakage occurred under both breakdown conditions, which can be ascribed to the dielectric breakdown triggered earlier and followed by the GaN layer breakdown. Combining the electric distribution from simulation and long-term monitoring of electric parameter, the peak electric fields under the gate edges at source and drain sides are confirmed as the main formation locations for per-location paths during negative gate voltage stress and off-state stress, respectively.