Study on the effects of proton irradiation on the dc characteristics of AlGaN/GaN high electron mobility transistors with source field plate

The effects of proton irradiation dose on the dc characteristics of AlGaN/GaN high electron mobility transistors (HEMTs) with source field plates were studied. The HEMTs were irradiated with various protons doses ranging from 5×10¹² to 5×10¹⁵cm^-2 at a fixed energy of 5 MeV. HEMTs irradiated with proton dose below 5×10 ¹³cm^-2 showed less than 2% degradation of either saturation drain current (I_DSS) or transconductance (g_m). Significant changes of these parameters were observed for the devices irradiated with doses above 5×10¹³cm^-2. HEMTs irradiated with the highest proton dose of 5×10¹⁵cm^-2 showed a reduction of I_DSS and g_m of 86% and 64.7%, and a positive V_th shift of 0.84V, respectively. Despite the significant I _DSS and g_m reductions, the off-state drain breakdown voltage (V_BR) was improved more than five times at this particular irradiation condition. The significant improvement of off-state drain breakdown voltage was attributed to the formation of a virtual gate at drain side of gate edge, which was the result of the generation of defect centers at AlGaN/GaN interface.