Compensating centers in Te-doped material were studied by means of positron annihilation. It was found that they contained a mono-vacancy which had a smaller volume than the isolated Ga vacancy. The observed defect complex was thermally stable up to 1000K, and existed in the neutral or negative charge state when the Fermi level was shifted to a mid-gap position as a result of electron irradiation. The results strongly suggested the validity of a model that was based upon thermodynamic considerations and which predicted a structure of TeAs-VGa.

R.Krause-Rehberg, G.Dlubek, A.Polity: Materials Science Forum, 1995, 196-201, 1649-54