Ab initio total energy calculations were performed to investigate the properties of intrinsic defects in GaN. It was found that the N defects were more stable than the Ga defects under N-rich conditions, and the results were generally consistent with those obtained by recent first-principles calculations. For the 4 types of N interstitials investigated, relaxation of all configurations led to a N–N<11•0> split configuration. The most stable configuration for Ga interstitials was the Ga octahedral interstitial, but the energy difference between the octahedral and tetrahedral configurations was small (<0.35eV) and depends on the basis set employed. While the <N–N> bond distance in the N–N split interstitial was very  close to that of a free N2 molecule, the Mulliken charge analysis indicated that the N atoms were partially charged, which was in contrast with previous theoretical suggestions. Based on the calculated results, the relative stabilities of various defects in GaN were determined.

Ab initio Calculations of Structural and Energetic Properties of Defects in Gallium Nitride. H.Y.Xiao, X.T.Zu, F.Gao, W.J.Weber: Journal of Applied Physics, 2008, 103[12], 123529