On-state electrical stress-induced degradation of NiO/β-Ga2O3 heterojunction pn diodes

Degradation and trap evolution in NiO/beta-Ga2O3 heterojunction pn diodes under on-state electrical stress were investigated in this work using deep-level transient spectroscopy measurements and density functional theory (DFT) calculations. The decrease in turn-on voltage and forward current appears to correlate with an increase in the concentration of the compensating acceptor-like traps. From the energy level of E-V + 1.3 eV, the corresponding acceptor-like traps can be attributed to the Ga vacancy complex with hydrogen (V-Ga-H). Interestingly, accompanied by the increase in V-Ga-H concentration, the self-trapped holes (STH) originally passivated by H may gradually recover. DFT calculations show a monotonous decrease in energy, suggesting the spontaneous diffusion of hydrogen from STH passivated sites to the adjacent V-Ga, which are generated under stress. This phenomenon leads to the recovery of STH and the generation of V-Ga-H. This investigation offers new insights into the degradation mechanisms of beta-Ga2O3-based devices under electrical stress.