Erbium-doped GaN samples grown with different V/III ratios through gas source molecular beam epitaxy were prepared to investigate the influence of the V/III ratio on the defect formation and the optical activity of the Er-related luminescence center. Obvious V/III ratio dependence was observed in photoluminescence measurement. Positron annihilation spectroscopy measurements suggested that VGa-VN vacancy-complexes formed in these samples and that the VN/VGa ratio depended on the V/III ratio. The generation of Er-VN defect complexes, which act as high optical active luminescence centers, was suggested as the cause of improved optical properties of Er-doped GaN grown with a lower V/III ratio.

Effect of V/III Flux Ratio on Luminescence Properties and Defect Formation of Er-Doped GaN. S.Chen, A.Uedono, S.Ishibashi, S.Tomita, H.Kudo, K.Akimoto: Applied Physics Letters, 2010, 96[5], 051907