DFT modelling of Ag doped As2S3 configurations

Abstract The generalized gradient approximation within density functional theory is used to calculate the total energies of Ag doped As2S3 configurations. The Ag is doped at octahedral, tetrahedral, c face centre and cell corner interstitial sites and As and S substitutional sites. It is found that with Ag at c face centre Ag0.25As2S3 configuration is most stable. The band structure, density of states and optical properties are investigated for this configuration. It is found that donor states are introduced below the EF in the gap region which leads to n type conductivity. The calculated values of refractive index, optical conductivity and absorption coefficient are more close to the available experimental data than those for substitutional configurations. Therefore Ag doped in As2S3 at low concentrations of Ag may occupy the c face centre interstitial site rather than any substituitional site.