Electronic and optical properties of CuGaS2: First-principles calculations

Electronic structure and optical properties of CuGaS2 are calculated using the full potential linearized augmented plane wave plus local orbitals method. The calculated equilibrium lattice is in reasonable agreement with the experimental data. The electronic structures indicate that CuGaS2 is a semiconductor with a direct bandgap of 0.81802 eV. Furthermore, other experiments and theory also show that this material has a direct bandgap. It is noted that there is quite strong hybridization between Ga 3d and S 3s orbitals, which belongs to the (GaS2)-. The complex dielectric functions are calculated, which are in good agreement with the available experimental results.