Forward and reverse voltage stress-induced degradation of 1.55kV p-NiO/n-Ga₂O₃ heterojunction barrier Schottky diode

To assess the reliability of Ga₂O₃ power diodes during the periodic switching between forward-conduction and reverse-blocking states of DC-DC converters or inverters, this study investigates the electrical degradation behavior and underlying mechanisms of p-NiO/n-Ga₂O₃ heterojunction barrier Schottky (HJBS) diodes under 5 V pulsed forward bias (PFB) and -600 V /448K high-temperature reverse bias (HTRB) stresses. To enable this study, a high-performance p-NiO/n-Ga₂O₃ HJBS diode with designed edge termination is fabricated, exhibiting suppressed high-temperature reverse leakage, a significantly enhanced breakdown voltage (BV) of 1550 V, and a specific on-resistance (R_on,sp) of 5.6 mΩ· cm². Using this device, the post-stress degradation and subsequent temperature-dependent recovery of J_F-V_F characteristics and C-V analysis reveal that, under PFB stress, only a 0.02 V increase in turn-on voltage (△V_on) and a 1.4% decrease in current capability (△R) are observed, which are attributed to electron capture and rapid emission from shallow surface acceptor-like traps. Owing to the suppression of self-heating effects, the degradation observed under PFB stress is significantly less pronounced than that under DC forward bias (DFB) stress. Under HTRB stress, a 0.12 V increase in △V_on and a 13% degradation in △R are observed, which are presumed to be caused by elevated temperature and strong surface electric fields that induce an increase in near-interface traps. Then, some electrons are subsequently captured by bulk traps via variable range hopping (VRH). These findings provide important insights for improving the reliability of Ga₂O₃ power devices.