Dielectric function and reflectivity spectrum of SiC polytypes - art. no. 125201

The frequency-dependent dielectric functions and reflectivity spectra of th e cubic 3C and two hexagonal 2H and 6H polytypes of SiC are investigated by state-of-the-art ab-initio techniques. To this end, we employ a Green's fu nction approach that enables us to include the relevant electronic correlat ion effects, in particular, the excitonic effects resulting from the electr on-hole interaction. These two-particle correlation effects have a very sig nificant influence on the optical properties. The resulting spectra are in good agreement with available experimental data while the spectra of indepe ndent-particle approaches show significant systematic deviations from exper iment.