Charge Trapping in Al₂O₃/$\beta$ -Ga₂O₃-Based MOS Capacitors

Abstract

Trapping characteristics of MOS structures with $\beta $ -Ga ₂ O ₃ substrates and Al ₂ O ₃ gate dielectrics are evaluated via constant-voltage stress and X-ray irradiation. Traps that affect bias-induced charging are located primarily in the Al ₂ O ₃ 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 Al ₂ O ₃ dielectric layer dominates device radiation response. The relatively modest radiation-induced charge trapping observed in these devices is promising for the potential future use of Al ₂ O ₃ / $\beta $ -Ga ₂ O ₃ devices in a space environment.