Structural information from the Raman spectrum of amorphous silicon

The Raman scattering from various model structures for amorphous silicon is computed. It is shown that the width of the ‘‘optic peak’’ increases roughly linearly with the rms bond-angle distortion Δ${\theta }_b$ of the network. The experimentally observed linewidths lead to 7.7°≤Δ${\theta }_b$≤10.5°. The smaller linewidths (and hence angles) correspond to networks that have been annealed at higher temperatures. These results are consistent with model-building experience which shows that it is impossible to construct fully bonded amorphous networks with Δ${\theta }_b$≤6.6°.