Pressure effect on the electronic and optical properties of the alkali antimonide semiconductors Cs3Sb, KCs2Sb, CsK2Sb and K3Sb: Ab initio study

We present first principles calculations of the effect of pressure on the electronic and optical properties of the alkali antimonides semiconductors K3Sb, K2CsSb, KCs2Sb and Cs3Sb by means of the full-potential linearized augmented plane wave method within the generalized gradient approximation. The band gap variation is not linear. The crossover pressure values are determined for K3Sb and K2CsSb. Under pressure the structures in the optical spectra shift towards higher energies for K3Sb and KCs2Sb whereas the threshold energy is lowered for K2CsSb and Cs3Sb. The electronic dielectric constant decreases with pressure for K3Sb while it increases for the other three compounds. Our results indicate that the absorption becomes strong in the UV region for KCs2Sb and Cs3Sb.