Degradation Characteristics of Normally-Off p-AlGaN Gate AlGaN/GaN HEMTs With 5 MeV Proton Irradiation

Proton irradiation at 5 MeV was performed on normally-off p-AlGaN gate AlGaN/GaN high electron mobility transistors (HEMTs). The increase of on-resistance and the degradation of subthreshold characteristics were observed after irradiation. The reduction of on-current was induced by displacement damage which also affected ungated devices with no p-AlGaN gate layer. Thermal annealing partially recovered this reduction. The subthreshold degradation with the threshold voltage (Vth) shift was proportional to the irradiation dose. TCAD simulation indicated that the decrease of hole concentration in p-AlGaN layer resulted in the negative shift of Vth and the subthreshold degradation.