Stability of GaN HEMT Device Under Static and Dynamic Gate Stress

In this work, we investigated the stability of a p-GaN gate with high electron mobility transistors (HEMTs) including an internal integrated gate circuit. A circuit was designed to improve p-GaN gate stability by using capacitance to release the hole into the p-GaN layer to mitigate the threshold voltage shift. Through pulse I-V measurement and positive bias temperature instability (PBTI) test, the carrier transporting behavior in the gate region achieved dynamic equilibrium at 5 V gate bias. The positive gate shift (Δ V_TH) of 0.4 V is observed with increasing voltage from 3 V to 8 V; Δ V_TH initially drops smoothly after release stresses by external capacitance discharge. Finally, integrated passive components and p-GaN gate HEMT circuit are recommended to mitigate the V_TH instability for E-mode HEMT.