On the nitrogen vacancy in GaN

The dominant electrically active defect produced by 0.42 MeV electron irradiation in GaN is a 70 meV donor. Since only N-sublattice displacements can be produced at this energy, and since theory predicts that the N interstitial is a deep acceptor in n-type GaN, we argue that the 70 meV donor is most likely the isolated N vacancy. The background shallow donors, in the 24-26 meV range, actually decrease in concentration, probably due to interactions with mobile N interstitials that are produced by the irradiation. Thus, the recent assignment of a photoluminescence (PL) line as an exciton bound to a 25 meV N-vacancy donor is incompatible with our results. Moreover, we do not observe that PL line in our sample. (C) 2003 American Institute of Physics.