Relation of the Si-H stretching frequency to the nanostructural Si-H bulk environment

We propose a model which describes the frequency shift (Delta wSM) of the stretching mode (SM) of Si-H monohydrides (MH's) when incorporated in hydrogenated amorphous silicon (a-Si:H) with respect to the unscreened MH SM at .apprx.2099+-2 cm-1. The model is based on an effective medium approxn. of the dielec. using multiple Lorentz-Lorenz dielecs., corresponding to a host dielec. with MH's embedded in cavities, sep. The Delta wSM as derived in this model correctly predicts all bulk MH-SM positions in a-Si:H films and relates it directly to the nanostructure of the MH bulk configurations. [on SciFinder (R)]