Optical Properties and Temperature Dependence of the Interband Transitions of 3C- and 6H-SiC in the Energy Region 5 to 10 eV

Abstract

A synchrotron radiation study of the optical properties of cubic (3C) and hexagonal (6H) SiC in the energy region 5 to 10 eV and over the temperature range 90 to 550 K is presented. Analysis of the dielectric function spectra reveals the location and temperature dependence of the occurring interband transitions. The results on 3C-SiC are compared in terms of transition energies with theoretical calculations in the literature and favour the assignment of the first direct gap to the X-point. The relation between the gaps of the polytypes is discussed. The results on the temperature dependence of the first direct gaps of 3C-SiC at the symmetry points Γ, X and L are compared to those of Si and diamond. Finally, the reflectivity spectra of both polytypes indicate very good sample quality and are compared in terms of absolute values and features to the existing experimental and theoretical data in the literature.