Optical and electron beam studies of gamma-irradiated AlGaN/GaN high-electron-mobility transistors

The impact of Co-60 gamma-irradiation on n-channel AlGaN/GaN high-electron-mobility transistors was studied by means of temperature-dependent electron beam-induced current (EBIC) and cathodoluminescence (CL) techniques. For the doses up to similar to 250 Gy, an enhancement of minority carrier transport was observed as evident from the EBIC measurements. This enhancement is associated with internal electron irradiation induced by the primary gamma photons. For the doses above similar to 250 Gy, deterioration in minority carrier transport was explained by carrier scattering on radiation-induced defects. It is shown that calculated activation energy from the EBIC and CL measurements follows exactly the same trend, which implies that the same underlying phenomenon is responsible for observed findings.