Raman scattering determination of structures for SiC polytypes: Quantitative evaluation with a revised model of lattice dynamics

Abstract

Quantitative structural analysis by measurements of Raman intensity profiles has been undertaken for silicon carbide (SiC) polytypes. Since the Raman intensity is sensitive to the choice of atomic displacements, previous models of lattice dynamics are reexamined. Force-constant parameters of a linear-chain model are determined so that calculated phonon dispersions and Raman intensity profiles fit the experimental results. The Raman intensity profiles calculated using these force constants agree quantitatively with the observed spectra for a number of polytypes. This agreement indicates that the set of the force constants thus determined can commonly be used for any polytypes of SiC and also that the bond polarizability concept is applicable to folded modes of both the acoustic and optical branches.