Local density functional calculations, using a real-space cluster approach, were used to model interstitial H and the dissociation of C-H and C-H- complexes. The equilibrium site was found to be on a Ga-As bond axis, for H0 and H+, and at a Ga anti-bonding site, for H-. It was also shown that a H2 molecule was stable in interstitial space and had a lower energy than the 2 possible H2* defects or widely separated single interstitial H atoms. The study of H in pure GaAs also yielded the information that interstitial H was a negative-U defect. It was found that the energy barrier to the dissociation of the C-H complex was 1.8eV, but that this was halved to 0.9eV in the case of C-H-.

S.J.Breuer, R.Jones, S.Oberg, P.R.Briddon: Materials Science Forum, 1995, 196-201, 951-6