The leakage current of GaN Schottky barrier ultra-violet photodetectors was investigated. It was found that photodetectors with undoped GaN, instead of lightly Si-doped GaN, as an active layer exhibited a much lower leakage current even when they had a higher dislocation density. It was also found that the density of Ga vacancies in undoped GaN was much lower than in Si-doped GaN. The Ga vacancies could enhance tunnelling and reduce the effective Schottky barrier height; leading to an increase in leakage current. This suggested that, when undoped GaN was used as the active layer, it was necessary to reduce the leakage current of GaN Schottky barrier ultra-violet photodetectors.

Role of Ga Vacancies in Enhancing the Leakage Current of GaN Schottky Barrier Ultraviolet Photodetectors. D.G.Zhao, S.Zhang, W.B.Liu, X.P.Hao, D.S.Jiang, J.J.Zhu, Z.S.Liu, H.Wang, S.M.Zhang, H.Yang, L.Wei: Chinese Physics B, 2010, 19[5], 057802