Electronic Properties of CdGa2S4: Ab Initio Calculations and Experimental Studies by Spectral Ellipsometry

Electronic properties of CdGa2S4 single crystals are studied experimentally by the spectral ellipsometry and also theoretically from the first principles using the density functional theory (DFT). From the ellipsometric studies in the energy range 0.7–6.5 eV, the imaginary and real parts of the dielectric function and the optical conductivity along and perpendicularly to the axis, the dispersion of the refractive index, extinction ratio, absorption factor, etc., have been determined. The estimations are performed for the direct energy gap width. The band structure, the origin of energy states, optical functions, and partial densities of states (PDOS) projected onto atoms are determined by calculations from the first principles. The results obtained by theoretical calculations are compared with the experimental data obtained in this work by the spectral ellipsometry method.