The microstructural properties of sputtered thin films, which had been pre-irradiated and γ-irradiated, were investigated. The results revealed that increasing doses of γ-rays could increase the incidence of N vacancies. These not only created a prominent deep-level luminescence, but also destroyed the crystallinity of the thin films. At low γ-ray doses (< 4Mrad), increasing the irradiation dose produced more associated Ga-H complexes and led to enhanced yellow-band emission. At high γ-ray doses (> 4Mrad), further increased doses could lead to the dissociation of Ga-H complexes and result in a repressed yellow-band emission. On the basis of Fourier-transform infra-red spectroscopy and yellow-band emission results, it was concluded that Ga-H complexes in the vicinity of N were probably the source of yellow-band emissions.

Effects of Gamma-Ray Irradiation on the Microstructural and Luminescent Properties of Radio-Frequency Magnetron-Sputtered GaN Thin Films. C.W.Wang, B.S.Soong, J.Y.Chen, C.L.Chen, Y.K.Su: Journal of Applied Physics, 2000, 88[11], 6355-8