Calculations were made of the electronic and atomic structures of neutral and charged N vacancies in AlxGa1-xN alloys by using a combination of first-principles methods. The treatment of the alloys was based upon the generalized quasi-chemical approach to disorder and composition effects, plus a cluster expansion which accounted for the various configurations. The point defects were modeled by super-cells which were multiples of the alloy clusters. The total-energy and electronic-structure calculations were performed within the density functional theory and the local spin density approximation. A study was made of the atomic structure, energetics and charge-dependent vacancy states of the various clusters.

Ab initio Theory of Native Defects in Alloys - Application to Charged N Vacancies in AlxGa1-xN. L.E.Ramos, J.Furthmüller, F.Bechstedt, L.M.R.Scolfaro, J.R.Leite: Journal of Physics - Condensed Matter, 2002, 14[10], 2577-89