Theoretical investigation of optical properties and band gap engineering for Zn1−xTMxTe (TM = Fe, Co) alloys by modified Becke–Johnson potential**Project supported by the Deanship of Scientific Research at King Saud University (for Shahid M Ramay) (Grant No. RG 1435-004), the University of the Punjab, Lahore for financial support through Faculty Research Grant Program (for M Hassan), and the HEC Pakistan

Abstract

The direct band gap ZnTe with transition metal (TM) impurities plays a vital role in optoelectronic and spintronic applications. In the present study, we use the advanced modified Becke–Johnson (mBJ) functional for performing the structural computations and detailed investigations of the optical characters in (, Co) alloys with . By employing the FP-LAPW method, we determine various optical parameters for the ternary alloys and for the end binaries. The calculated static dielectric constants and optical band gaps for (, Co) have an inverse relation that verifies the Penn model. We find that the static dielectric constant is nearly equal to the square of the static refractive index, and both increase with TM content. Furthermore, we also find a slight shift of peaks to a higher energy region with increasing TM concentration. The decreasing band gap and high value of the absorption in the visible region of electromagnetic spectrum make these alloys suitable for photonic and solar cell applications.