Evolution of structure, morphology, and reactivity of hydrogenated amorphous silicon film surfaces grown by molecular-dynamics simulation

The relationship between the structure, H coverage, morphology, and reactiv ity of plasma deposited hydrogenated amorphous silicon (a-Si:H) film surfac es was investigated using molecular-dynamics simulations. Surfaces of a-Si: H films grown with SiH3 as the sole deposition precursor are found to be re markably smooth due to a valley-filling mechanism where mobile precursors, such as SiH3 and Si2H6, diffuse and react with dangling bonds in the valley s on the surface. Surface valleys are reactive due to the increased concent ration of dangling bonds and decreased H coverage in these regions. The pre viously speculated physisorbed configuration, where SiH3 is weakly bound to the surface through a H atom, is highly unlikely to be the mobile precurso r state. (C) 2001 American Institute of Physics.