Raman-scattering measurements and fracton interpretation of vibrational properties of amorphous silicon

Results of Raman scattering on a-Si:H films are presented at frequencies from 20 to 2500 cm^-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 ωco1 between phonon and fracton regimes and the fractal exponent ({σ}+d-D)d ̃ \~{}{}/D, obtained from the frequency dependence on the Raman scattering intensity, have been determined.