An investigation was made, of the behavior of O in these materials, by using first-principles calculations. In the case of GaAs, the resultant stable atomic configurations and their stability were in good agreement with experiment. It was found that many features, such as a stable site, negative-U nature, charge-state dependent diffusion path and relatively high diffusion barrier height in the negatively charged state, were similar for both GaAs and AlAs. Some features nevertheless depended upon the host. It was noted that an asymmetry effect during diffusion was marked, in p-type hosts, for both GaAs and AlAs; but the effect had differing characteristics, depending upon the host. The O was more stable in AlAs than in GaAs. All of the basic properties could be explained by: the large electron negativity of O, the strong O-Al bond and the large polarization of AlAs hosts.

Diffusion and Stability of Oxygen in GaAs and AlAs A.Taguchi, H.Kageshima: Physical Review B, 1999, 60[8], 5383-91