Degradation Behavior and Mechanisms of E-mode GaN HEMTs with p-GaN Gate under High Temperature Gate Bias Stress

In this work, the degradation behavior and the physical mechanism of the AlGaN/GaN HEMTs with p-GaN gate after HTGB stress were investigated. The experiment results show that the threshold voltage ($V_{th})$ and gate leakage currents (Igss) increase obviously. At the same time, the drain-source current (Ids) decreases significantly after HTGB stress. However, the on-state resistance (Ron) and the blocking characteristics have no change. Furthermore, obvious decrease was observed in the $C_{g}-V_{g}$ curve, and it shows that the interface state increases significantly after HTGB stress. The physical mechanism of the degradation behavior could be attributed to electromigration and the formation of new traps at p-GaN layer, AlGaN barrier, p-GaN/AlGaN interface, and AlGaN/GaN interface. This work could be a useful reference for the study of AlGaN/GaN HEMTs.