Ab Initio Calculations and Experimental Study of the Electronic Properties of CdGa 2 Se 4 Single Crystals by Spectral Ellipsometry

The electronic properties of CdGa 2 Sе 4 single crystals have been investigated experimentally using spectral ellipsometry and theoretically (ab initio) within the density functional theory (DFT). Based on the ellipsometric measurements in the energy range of 0.7–6.5 eV, the imaginary and real parts of the dielectric function for incident light polarized along and perpendicular to the crystal optical axis, as well as the dispersion of the refractive indices and extinction and absorption coefficients, were determined. The energy band structure, origin of energy states, optical functions, and the partial densities of states (PDOS) projected on atoms were determined from ab initio calculations. The theoretically calculated results are compared with the spectral ellipsometry data.