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

Degradation and trap evolution in NiO/β-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 EV + 1.3 eV, the corresponding acceptor-like traps can be attributed to the Ga vacancy complex with hydrogen (VGa-H). Interestingly, accompanied by the increase in VGa-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 VGa, which are generated under stress. This phenomenon leads to the recovery of STH and the generation of VGa-H. This investigation offers new insights into the degradation mechanisms of β-Ga2O3-based devices under electrical stress.