The substitutional O defect was investigated by using magnetic circular dichroism of absorption, optically detected magnetic resonance and optically detected electron-nuclear double resonance techniques. The paramagnetic state of the 3 charge states, which had previously been identified by means of infra-red absorption measurements, was attributed to the B’ state. The optically detected electron-nuclear double resonance spectra could be explained by assuming that the O atom occupied an As site, but was displaced from the normal lattice position in a <100> direction. The superhyperfine interactions and spin densities for several As and Ga neighbors were resolved.

M.Linde, H.C.Alt, J.M.Spaeth: Materials Science Forum, 1995, 196-201, 213-8