Theory of hydrogen-related metastability in disordered silicon

The properties of hydrogen in crystalline silicon and in a realistic model of hydrogenated amorphous silicon were analyzed. It was found that the hydrogen can break isolated bulk silicon bonds to form two Si-H bonds with both hydrogens in between the original silicon atoms. The complex was found to had the appropriate energetics and H-H separation to be consistent with experiments regarding reversible metastability in a-Si:H. The results show that the complex provides a microscopic model for new metastable complexes observed in amorphous silicon.