Hydrogen (and Muonium) in Crystalline Silicon: Static Properties and Diffusion Mechanisms

A two-channel model is first proposed which accounts for the two activation energies lately observed for hydrogen diffusion in c -Si. A unified understanding of the hydrogen and muonium static properties and of their thermally activated processes is given. This is obtained in terms of a stable state at a near bond centre site, of a metastable state at the tetrahedral site and of energy barrier arguments. These results have been obtained in a cluster approach by a Hartree-Fock analysis of the hydrogen potential energy surface.