AlGaN/GaN High Electron Mobility Transistors were exposed to 60Co gamma-irradiation to doses up to 300Gy. The impact of Compton- electron injection (due to gamma-irradiation) is studied through monitoring of minority carrier transport using Electron Beam Induced Current (EBIC) technique. Temperature dependent EBIC measurements were conducted on devices before and after exposure to the irradiation, which provide us with critical information on gamma-irradiation induced defects in the material. As a result of irradiation, minority carrier diffusion length increases significantly, with an accompanying decrease in the activation energy. This is consistent with the longer life time of minority carrier in the material’s valence band as a result of an internal electron injection and subsequent trapping of Compton electrons on neutral levels.