Recovery of drain-induced threshold voltage shift by positive gate bias in GaN power HEMTs with p-GaN gate

Abstract

We demonstrate that exposure to positive gate bias can favor a fast recovery of the threshold voltage variation induced by off-state stress, in p-GaN gate high electron mobility transistors. Two process splits were investigated, having different Schottky barriers at the metal/p-GaN junction. Results indicate that: (a) drain stress may result in significant threshold voltage increase; (b) devices with sufficiently high gate leakage current show an immediate recovery after gate turn-on, resulting in stable operation in actual applications. The contribution of leakage current is demonstrated, based on recovery experiments at different voltages and for the same rate of hole injection from the gate.