Existing growth mechanisms of hydrogenated amorphous Si (a-Si:H) and microcrystalline Si (μc-Si) assumed that the growth species SiH3 could diffuse over the H-saturated Si surface. However, other calculations suggested that this could not happen. Local density formalism pseudopotential calculations of the binding of SiH3 to H-terminated (111)Si surfaces were carried out. The bound site was not the 3-center Si---H---Si bridging site previously assumed. It had a direct Si---Si bond between the SiH3 and the surface Si, and the surface H was displaced to a bond center of a surface Si---Si bond. A bound site validated conventional models of growth of a-Si:H and μc-Si, in which a mobile growth species created smooth surfaces.

Surface Diffusion of SiH3 Radicals and Growth Mechanism of a-Si:H and Microcrystalline Si. R.Dewarrat, J.Robertson: Thin Solid Films, 2003, 427[1-2], 11-5