Total-energy pseudopotential methods were used to study the structures, binding energies and local vibrational modes of various models for the Ga-O-Ga defect. It was found that previously proposed models for OAs (off-centered substitutional O in As vacancy) and Oi (O on a tetrahedral interstitial site) were inconsistent with experimental data. An alternative model, (AsGa)2-OAs (two As antisites and one off-centered substitutional O in an As vacancy), was proposed. Its properties were in excellent agreement with experiment.

Microscopic Structure of Oxygen Defects in Gallium Arsenide M.Pesola, J.Von Boehm, V.Sammalkorpi, T.Mattila, R.M.Nieminen: Physical Review B, 1999, 60[24], R16267-70