Large atomic displacements associated with the nitrogen antisite in GaN

We present results of an extensive theoretical study of the nitrogen antisite in GaN. The neutral antisite in c-GaN is reported to exhibit metastable behavior similar to the arsenic antisite in GaAs. The feature of interest is the existence of the negative charge states of the nitrogen antisite. Their stability is a consequence of the large band gap. The nitrogen antisite undergoes in the negative charge states a large spontaneous Jahn-Teller displacement in the [111] direction, both in the cubic and in the wurtzite phase. The connection between the nitrogen antisite and the yellow luminescence commonly observed in GaN is discussed.