Charge Trapping in Al2O3/β-Ga2O3-Based MOS Capacitors

Trapping characteristics of MOS structures with beta-Ga2O3 substrates and Al2O3 gate dielectrics are evaluated via constant-voltage stress and X-ray irradiation. Traps that affect bias-inducedcharging are located primarily in the Al2O3 dielectric layer, and are distributed broadly in time and/or energy. Stress-induced flatband voltage shifts are reduced by N-2 annealing. Trap-assisted tunneling is shown to be responsible for the observed gate leakage. Hole trapping in the Al2O3 dielectric layer dominates device radiation response. The relativelymodest radiation-induced charge trapping observed in these devices is promising for the potential future use of Al2O3/beta-Ga2O3 devices in a space environment.