INVESTIGATION OF THE ELECTRONIC-TRANSITIONS OF CUBIC SIC

In this work we perform measurements with spectroscopic ellipsometry on the dielectric function of cubic bulk SiC (SiC(3C)) in the VUV region and theoretical band structure calculations on the material with the LMTO method. This is the first direct observation of the dielectric function in this energy range. The observed features are analyzed with standard lineshapes, the existence of four critical points (CPs) is revealed at energies 6.4, 6.9, 7.1 and 7.6 eV, and their temperature dependence was found to be similar to that of diamond. The calculated reflectivity from the dielectric function is compared to results from literature and certain ambiguities regarding the position and absolute values of the observed peaks are discussed. The LMTO calculations indicate the indirect gap to run along the GAMMA-X axis, while the first direct gap seems to be due to an electronic transition at the X-point, in contradiction to most published results. Finally, some ambiguities concerning the assignment of the interband transition of SiC(3C) are also discussed and commented.