Low-frequency noise in AlGaN/GaN high electron mobility transistors irradiated by γ-ray quanta

Room temperature current-voltage and noise measurements have been made before and after gamma irradiation on AlGaN/GaN high electron mobility transistors (HEMTs) grown on sapphire. The saturation current due to radiation-induced defects shows a nonlinear dependence on radiation dose. The deviation of the device parameters does not exceed 20% at highest radiation dose 10(9) Rad and the devices with larger gate lengths demonstrate a higher radiation hardness to the Co-60 gamma rays. The noise spectra of devices after gamma irradiation follow the flicker noise (1/f(gamma)) dependence with the exponent gamma close to one. The Hooge parameter estimated for the HEMTs after gamma irradiation dose does not show a gate-bias dependence and increases by approximately three to five times at radiation dose 2 x 10(8) Rad. The analysis of noise spectra allowed to identify the major sources of noise generation in the investigated HEMT heterostructures.