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 gamma -ray irradiated were systematically investigated. A nalytical results revealed that the increasing doses of gamma rays could en hance the occurrence of more nitrogen vacancies, which not only created a p rominent deep level luminescence but also destroyed the crystallinity of Ga N thin films. For low dose of gamma -ray irradiation [less than or equal to 4 Mrad (GaN)], evidence showed that by raising the irradiation dose, more a ssociated Ga-H complexes would be effectively promoted, yielding an enhance d yellow band emission. However, for high dose of gamma -ray irradiation [> 4 Mrad (GaN)], further higher doses of gamma rays could lead to the dissoci ation of Ga-H complexes in GaN samples, resulting in a repressed yellow ban d emission. From both the Fourier transform infrared spectroscopy and yello w band emission results, it is strongly suggested that Ga-H complexes in th e vicinity of N most probably act as the origin of yellow band emission in GaN material. (C) 2000 American Institute of Physics. [S0021-8979(00)08724- 7].