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

In this work, threshold voltage ($V _{\mathbf{TH}}$) 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 $V _{\mathbf{TH}}$ 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 $V _{\mathbf{TH}}$ keeps shifting positively until it saturates, indicating charge trapping in barrier and/or buffer layer gradually dominates the $V _{\mathbf{TH}}$ shifts.