Deep acceptors trapped at threading-edge dislocations in GaN

Local-density-functional methods are used to examine the behavior of the oxygen defect, gallium vacancy, and related defect complexes trapped at threading-edge dislocations in GaN. These defects are found to be particularly stable at the core of the dislocation where oxygen sits twofold coordinated in a bridge position. V-Ga-O-N is found to be a deep double acceptor, V-Ga-(O-N)(2) is a deep single acceptor, and V-Ga-(O-N)(3) at the dislocation core is electrically inactive. We suggest that the first two defects are responsible for a deep acceptor level associated with the midgap yellow luminescence band. [S0163-1829(98)07143-4].