“M”-Shaped Threshold Voltage Shift Induced by Competitive Positive/Negative Gate Switching Stress in Schottky-Type p-GaN Gate HEMTs

This work investigates the threshold voltage ( ${V}_{\text {th}}\text {)}$ instability in Schottky-type p-GaN gate HEMTs subjected to positive/negative gate switching stress. Under the gate switching stress, a characteristic “M”-shaped ${V}_{\text {th}}$ curve with elevated ${V}_{\text {GS,ON}}$ is revealed. This pattern is ascribed to the competitive transport of electrons and holes. Considering the condition of reduced ${V}_{\text {GS, OFF}}$ , an increasing ${V} _{\text {th}}$ has also been observed, which is attributed to the curtailed electron emission while the promoted hole release. Further, with the increasing of the duty cycle, a positive ${V}_{\text {th}}$ shift at the lower ${V}_{\text {GS, ON}}$ and a negative shift at higher ${V}_{\text {GS, ON}}$ are needs to be taken seriously, and it also confirm the competitive mechanism in the abnormal “M”-shaped ${V}_{\text {th}}$ instability. The research highlights that the impact of positive/negative gate switching stress on ${V}_{\text {th}}$ instability are significant and cannot be neglected.