DFT study of the structural and optoelectronic properties of Cd1−xAgxS half metallic alloys

Abstract In this work, we report a theoretical investigation of the structural, electronic and optical properties of Cd 1 − x Ag x S alloys with a wurtzite structure. The calculations were performed using the density functional theory (DFT). The full potential linearized augmented plane wave (FPLAPW) scheme, implemented in Wien2k package, was employed. The modified Becke–Johnson potential with generalized gradient approximation (mBJGGA), which combines the Becke–Johnson exchange potential with the generalized gradient approximation correlation potential, was used to evaluate the alloys band structure. The study was carried out for the composition of silver x = 0 , 0.027, and 0.055. The obtained band structures and the density of states of these alloys revel that by increasing the silver composition in CdS matrix, the Fermi level cross the E(k) curves in the majority-spin states showing a metallic behavior. While the minority-spin state is semiconducting. A band gap channel was observed between the spin up and spin down level giving rise to a half metallic behavior. The origin of this bandgap is attributed to the silver d-band hybridization. The optical properties were also investigated and were found to be deeply affected by the silver composition. The optical absorption is gradually shifted to the lower energy and the compound becomes more absorbent in the infrared region. The structural and optoelectronic proprieties of the half metal Ag-doped CdS materials, were investigated and are presented in the current study and discussed in details. The findings of the study show that Cd 1 − x Ag x S alloys with their spin-based properties could pave the way for many novel  optoelectronic devices in addition to spintronics applications.