Abstract
The energy band gap of Zn-0.75 Cd0.25S1-zSez (x=0,0.25,0.5, 0.75 and 1.0) quaternary alloys have been calculated by using the full-potential linearized augmented plane wave (FPLAPW) method and the Tran-Blaha modified Becke-Johnson (TBmBJ) potential. The lattice volume was first relaxed within the generalized gradient approximation (GGA). The obtained values of the band gaps are found to decrease linearly from 3.61 eV down to 2.83 eV as the content of the Se ion increases in the lattice. These values are in agreement with those reported experimentally for some of ZnS and ZnSe structures. The energies of the interband transitions were determined from the dielectric functions. It is seen that the main interband transitions peaks obtained after the TBmBJ potential is comparable with some reported experimental data. These finding supports the use of the TBmBJ potential as an accurate method in obtaining the energy band gap and the optical constants of semiconductors. (C) 2015 Elsevier GmbH. All rights reserved.