Theoretical analysis of Raman spectra of finite stage Si/(Si,Ge) Fibonacci superlattices.

Raman scattering results for acoustic phonons in Si-Ge1 Fibonacci superlattices with low stage numbers are analyzed and shown to have significant deviations from the infinite stage assumption implicit in standard theoretical models. We show that a quantitative description of the observed spectra is possible only with a "sample specific" theory which takes into account the presence of the substrate and the free surface. A nearest neighbor linear chain model is used to calculate Raman spectra which are in good agreement with experiment.