Proton Bombardment Effects on Normally-off AlGaN/GaN-on-Si Recessed MISHeterostructure FETs

Proton irradiation at 5 MeV was performed on normally-off AlGaN/GaN metal-insulator-semiconductor heterostructure field effect transistors and normally-on Schottky high electron mobility transistors fabricated on the same GaN-on-Si wafer. The positive shift of threshold voltage (V-th) and the increase of on-resistance were observed from both devices after irradiation. V-th shift was increased as the irradiation dose was raised while leakage characteristics were not degraded. We also observed the increase of sheet resistance with negligible change of contact resistance. The increase of density of states by irradiation was probed by differential subthreshold ideality factor technique and pulsed I-V measurements. The positive shift of V-th is attributed to the effect of electron traps generated by proton bombardment damage. The degradation was partially recovered by thermal annealing.