Silicon Ion Irradiation Effects on AlGaN/GaN Heterostructures Grown by Metalorganic Chemical Vapour Deposition

Irradiation effects of 120 MeV silicon ion with the fluence of 5 x 10(12) ions/cm(2) at room temperature and low temperature (77 K) on AlGaN/GaN heterostructures have been studied to probe the radiation tolerance for space applications. XRD results explicitly showed there were no compositional changes and additional phase formation due to irradiation. Smooth surface with atomic steps and terrace features has been observed in the pristine sample; upon irradiation, the surface become rough with annihilated surface steps. Atomic force microscopy images depict the nano and micro structures formation for the silicon ion irradiated AlGaN/GaN samples at room temperature and low temperature (77 K), respectively. Photoluminescence measurements revealed the blue shift of AlGaN layer in the low temperature irradiated samples. Intensity of defect peaks around 2.5-3.2 eV increases for irradiated samples. Low temperature irradiation decreases the radiation tolerance and increases the defects and surface roughness of the AlGaN/GaN heterostructures.