Effect of proton irradiation dose on InAlN/GaN metal-oxide semiconductor high electron mobility transistors with Al₂O₃ gate oxide

The effects of proton irradiation on the dc performance of InAlN/GaN metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) with Al₂O₃ as the gate oxide were investigated. The InAlN/GaN MOSHEMTs were irradiated with doses ranging from 1 × 10¹³ to 1 × 10¹⁵cm^-2 at a fixed energy of 5 MeV. There was minimal damage induced in the two dimensional electron gas at the lowest irradiation dose with no measurable increase in sheet resistance, whereas a 9.7% increase of the sheet resistance was observed at the highest irradiation dose. By sharp contrast, all irradiation doses created more severe degradation in the Ohmic metal contacts, with increases of specific contact resistance from 54% to 114% over the range of doses investigated. These resulted in source-drain current-voltage decreases ranging from 96 to 242 mA/mm over this dose range. The trap density determined from temperature dependent drain current subthreshold swing measurements increased from 1.6 × 10¹³cm^-2 V^-1 for the reference MOSHEMTs to 6.7 × 10¹³cm^-2 V^-1 for devices irradiated with the highest dose. The carrier removal rate was 1287 ± 64 cm^-1, higher than the authors previously observed in AlGaN/GaN MOSHEMTs for the same proton energy and consistent with the lower average bond energy of the InAlN.