Local density-functional methods were used to examine the behavior of O defect, Ga vacancy, and related defect complexes which were trapped at threading edge-dislocations. These defects were found to be particularly stable at the core of the dislocation, where O sat 2-fold coordinated in a bridge position. The VGa-ON complex was found to be a deep double-acceptor, while VGa-(ON)2 was a deep single acceptor, and VGa-(ON)3 at the dislocation core was electrically inactive. It was suggested that the first 2 defects were responsible for a deep acceptor level that was associated with the mid-gap yellow luminescence band.

Deep acceptors trapped at threading edge dislocations in GaN J.Elsner, R.Jones, M.I.Heggie, P.K.Sitch, M.Haugk, T.Frauenheim, S.Oberg, P.R.Briddon: Physical Review B, 1998, 58[19], 12571-4