Impact of Hole-Deficiency and Charge Trapping on Threshold Voltage Stability of p-GaN HEMT under Reverse-bias Stress

In this work, threshold voltage (VTH) stability under long-term off-state stress with various drain-to-source voltages was characterized in the Schottky type p-GaN gate high electron mobility transistors (HEMTs). The VTH shows a sudden increase at the very beginning of the stress, which is suggested to be caused by the hole-deficiency; while during the long-term stress, the VTH keeps shifting positively until it saturates, indicating charge trapping in barrier and/or buffer layer gradually dominates the VTH shifts.