Effects of gamma-ray irradiation on the microstructural and luminescent properties of radio-frequency magnetron-sputtered GaN thin films

The microstructural and luminescent properties of sputtered GaN thin films preiiradiated and γ-ray irradiated were systematically investigated. Analytical results revealed that the increasing doses of γ rays could enhance the occurrence of more nitrogen vacancies, which not only created a prominent deep level luminescence but also destroyed the crystallinity of GaN thin films. For low dose of γ-ray irradiation [≦4 Mrad (GaN)], evidence showed that by raising the irradiation dose, more associated Ga–H complexes would be effectively promoted, yielding an enhanced yellow band emission. However, for high dose of γ-ray irradiation [>4 Mrad (GaN)], further higher doses of γ rays could lead to the dissociation of Ga–H complexes in GaN samples, resulting in a repressed yellow band emission. From both the Fourier transform infrared spectroscopy and yellow band emission results, it is strongly suggested that Ga–H complexes in the vicinity of N most probably act as the origin of yellow band emission in GaN material.