Ab initio total-energy calculations were presented for intrinsic defects in GaAs with a particular emphasis on hyperfine interactions in order to clarify the atomic structure of the various AsGa-related defects. For the AsGa-X2 defect complex the interpretation as an AsGa-VAs antisite-vacancy pair as was considered so far was challenged. An AsGa-GaAs antistructure pair was the most likely identification. It was also unlikely that the AsGa-X1 defect could be identified as a distant antistructure pair as was considered from magnetic resonance experiments. The theoretical results obtained for the isolated AsGa point defect agreed with the experimental data reported for the defect identified as isolated AsGa and, with the exception of a small broadening of the nearest-neighbor lines and of a moderate splitting in the fifth shell, for the EL2 as well. It was speculated that, at room temperature, EL2 would be an isolated AsGa defect which lowered its symmetry; attracting some other mobile defect at the low temperatures which were required for magnetic resonance experiments. Calculations were made of the binding energies of antisites bound to a distant shallow acceptor and of the influence of the pairing upon the hyperfine interactions. It was shown that this mechanism could explain the broadening of the nearest-neighbor lines but not the splitting in the fifth shell.

Defect Identification in the AsGa Family in GaAs. H.Overhof, J.M.Spaeth: Physical Review B, 2005, 72[11], 115205 (10pp)