A comparative density functional theory (DFT) investigation of the structural and opto-electronic properties of Zn-doped CuAlS2 chalcopyrite and (Cu, Al) co-doped ZnS compound using the modified Becke-Johnson (mBJ)

Abstract

In, this work, we have developed a comparative study of the structural and opto-electronic properties of Zn doped CuAlS₂ chalcopyrite and (Cu, Al) co-doped ZnS compound using the first principles calculation based on density functional theory (DFT) and FP-LAPW method. The exchange and correlation effects are treated by the Perdew– Burke–Ernzerhof generalized gradient approximation (GGA). Additionally, we used the modified Becke-Johnson (mBJ). The structural parameters found to be increase by Zn doping chalcopyrite and decreased by (Cu, Al) co-doping ZnS compound. The calculated band structure, the total and partial densities of states (TDOS and PDOS) show the semiconducting character of all systems with a direct band gap with a noticed decrease in its value by Zn doping CuAlS₂ and (Cu, Al) co-doping ZnS. The optical properties such as the real and imaginary parts of the dielectric function and the absorption coefficient, the refractive index, the extinction coefficient and the optical conductivity are calculated and presented. The calculated optical properties found to be more interesting in the visible region. The presence of Cu, Al and Zn together may enhance the optical properties in the IR region. This comparative analysis is a significant advancement over previous standalone studies. As far as we are aware, no theorical publications have been written about the electronic and optical properties of Cu, Al co-doped ZnS compound using GGA and GGA + mBJ.