Electrical Degradations of p-GaN HEMT under High Off-state Bias Stress with Negative Gate Voltage

The shifts of electrical parameters for p-GaN high electron mobility transistor (HEMT) under high off-state bias stress with negative gate voltage are investigated in this paper. Comparing to the conventional off-state bias stress with zero gate voltage, a more significant positive shift of threshold voltage and a more evident decrease of gate leakage current were observed under negative gate bias stress condition. The dominant degradation mechanism is suggested that electron traps induced by high electric field at gate-source access region capture more electrons in the barrier layer with the increasing negative gate bias. This work is of significance for the researches on the long-term reliability of the practical system using p-GaN HEMT device.