Epitaxial single-crystal GaN films on sapphire were irradiated at low and room temperatures using O+ ions over a range of fluences. The accumulation of disorder on the Ga sub-lattice was investigated based upon He+ Rutherford back-scattering analysis along the <00▪1>-axial channeling direction. The degree of disorder in the O+ irradiated GaN increases at low doses and saturated above 10dpa. The microstructures of two O+-irradiated specimens were characterized by using high-resolution transmission electron microscopy. Similar planar defect structures at the saturated disorder level were observed for as-irradiated and thermally annealed GaN. The growth and annihilation of these defects during ion irradiation and thermal annealing were believed to contribute to the saturation and stability of defect concentrations.

Ion-Beam Irradiation Induced Defects in Gallium Nitride. W.Jiang, W.J.Weber, C.M.Wang: Nuclear Instruments and Methods in Physics Research B, 2003, 206, 1037-41