Study on the Electronic Structures of ZnS and Ag-doped ZnS from Density Functional Theory

The band structures and electronic structures of pristine and Ag-doped zinc blende ZnS were calculated with the ab-initio ultra-soft pseudopotential plane wave approximation method based on density functional theory (DFT). The results show that Ag-doping narrows the band gap of ZnS and the acceptor impurity level is introduced by importing impurity Ag. It is pointed out that the acceptor level is hybridization due to the overlapping of the Ag-4d and S-3p. By analysis of Mulliken populations, Zn-S bond has strong covalence in ZnS and the covalence of bond Ag-S is weakest after Ag-doped.