Irradiation effects on AlGaN HFET devices and GaN layers

AlGaN/GaN heterostructure field effect transistors (HFETs) were irradiated with protons as well as carbon, oxygen, iron and krypton ions of high ( 68 and 120 MeV) and low ( 2 MeV) energy with fluences in the range from 1 x 10(7) to 1 x 10(13) cm(-2). High energy irradiation with protons, carbon and oxygen produced no degradation in devices while krypton irradiation at the fluence of 1 x 10(10) cm(-2) resulted in a small reduction of 2% in the transconductance. Similarly, for GaN samples irradiated with protons, carbon and oxygen at high energy no changes were seen by XRD, PL and Hall effect, while changes in lattice constant and a reduction in PL intensity were observed after irradiation with high energy krypton. Low energy irradiation with carbon and oxygen at a fluence of 5 x 10(10) cm(-2) results in small change in the device performance while remarkable changes in device characteristics are seen at a fluence of 1 x 10(12) cm(-2) for carbon, oxygen, iron and krypton irradiation. Similarly changes are also observed by XRD, PL and Hall effect for the thick GaN layer irradiated at the fluence of 1 x 10(12) cm(-2). The device results and GaN layer properties are strongly correlated.