The nature of H bonding and diffusion in crystalline material was investigated by using a first-principles self-consistent pseudopotential method. The relative energies of interstitial atomic H, diatomic H complexes, and shallow dopant-H complexes were considered. A mechanism for H diffusion was presented which involved a new metastable diatomic complex with a much lower activation barrier for H diffusion than that for molecular H. It was suggested that metastable diatomic-complex formation was very likely to occur at low temperatures and at high H concentrations; especially in n-type material. Diffusion via an ionized H form was suggested to be more likely to occur in p-type material.

K.J.Chang, D.J.Chadi: Physical Review B, 1989, 40[17], 11644-53