Gate Reliability and VTH Stability Investigations of p-GaN HEMTs

Gate reliability and reverse-bias-stress-induced VTH instability issues were investigated in the E-mode p-GaN gate HEMTs. A GaN-based p-n junction gate (PNJ) HEMT featuring an n-GaN/p-GaN/AlGaN/GaN gate stack was proposed to effectively reduce the gate leakage and enlarge safe gate operation bias region of the p-GaN gate devices. The VTH instability of the p-GaN gate HEMTs under reverse-bias stress has also been systematically investigated under various temperatures and different drain biases. Two different mechanisms are suggested to dominant the VTH shifts during the short-and long-term stress, respectively.