Results of Raman scattering on a-Si:H films are presented at frequencies from 20 to 2500 ${\mathrm{cm}}^{\mathrm{-}1}$. The frequency and temperature dependence of the Stokes/anti-Stokes ratio of Raman scattering intensity show the boson character of the observed broad background signal. It has been shown that the fractal model can be successfully applied to a-Si:H as well. The crossover frequency ${\mathrm{\omega }}_{\mathrm{co}1\mathrm{}}$ between phonon and fracton regimes and the fractal exponent (σ+d-D)d̃/D, obtained from the frequency dependence on the Raman scattering intensity, have been determined.

• Received 4 August 1992

DOI:https://doi.org/10.1103/PhysRevB.46.14893