The stability and electronic properties of metal (Ni, Au)-vacancy complexes in GaN were studied using density functional calculations. Two complexes (NiGa-VN and VGa-Aui-VN) were found to exhibit relatively low formation energies in their neutral charge state under p-type conditions and were predicted to act as deep acceptors in GaN. As such they were unlikely to contribute to the hole carrier concentration in p-GaN and were probably not responsible for the low electrical resistance of Au/Ni contacts. They may, however, act as compensation centers in n-GaN.

Metal (Ni,Au)-Vacancy Complexes in GaN. J.von Pezold, P.D.Bristowe: Physica Status Solidi C, 2006, 3[6], 1783-6