Degradation of dc characteristics of InAlN/GaN high electron mobility transistors by 5 MeV proton irradiation

The dc characteristics of InAlN/GaN high electron mobility transistors were measured before and after irradiation with 5 MeV protons at doses up to 2 × 1015 cm−2. The on/off ratio degraded by two orders of magnitude for the highest dose, while the subthreshold slope increased from 77 to 122 mV/decade under these conditions. There was little change in transconductance or gate or drain currents for doses up to 2 × 1013 cm−2, but for the highest dose the drain current and transconductance decreased by ∼40% while the reverse gate current increased by a factor of ∼6. The minority carrier diffusion length was around 1 μm independent of proton dose. The InAlN/GaN heterostructure is at least as radiation hard as its AlGaN/GaN counterpart.