It was recalled that H was known to play a key role in the p-type doping of this material. It was believed that the H passivated Mg dopants and was then removed by annealing. First-principles calculations were presented which showed that the doping process was significantly more complex than this. Several substitutional-interstitial complexes formed and could bind H, with vibrational frequencies that correlated well with hitherto unidentified lines. It was predicted that these defects, which limited doping efficiency, could be eliminated by annealing in an atmosphere of H and N before final annealing to remove H.

Novel defect complexes and their role in the p-type doping of GaN F.A.Reboredo, S.T.Pantelides: Physical Review Letters, 1999, 82[9], 1887-90