Phonons in polysilane alloys

A study of the vibrational properties of polysilanelike conformations in amorphous hydrogenated silicon (a-Si: H) is presented. With the use of the valence force-field representation of the near-neighbor interactions, the generalized cluster-Bethe-lattice method, and a chemical bonding model for obtaining realistic force constants, the one-phonon densities of states for various polysilanelike conformations [e.g., SiH₂, (SiH₂)₃, (SiH₂)ₙ] in an amorphous silicon matrix are calculated. Our results indicate that all of the features which have been reported in the 800- to 900-cm^-1 frequency regime of the infrared absorption and Raman scattering spectra of a-Si: H alloys can be attributed to the vibrational modes of polysilanelike conformations.