First principle study of optical and electronic response of Ca-based novel chalcopyrite compounds

A series of Ca-based novel chalcopyrite compounds have been studied by means of the full-potential linearized augmented plane wave method. In this work, we have used one of the utmost precise exchange and correlation functional of Tran-Blaha modified Becke Johnson (TB-mBJ) for the investigation of electronic as well as optical properties of Ca based chalcopyrite compounds namely, CaXY2 (X = Ge, Sn; Y = N, P, As). The computed energy bands and density of states reveals the semiconducting nature of all these studied compounds. The bandgap of CaXY2 (X = Ge, Sn; Y = N, P, As) compounds are found within the energy range 1.60-3.74 eV. The frequency dependent optical properties are investigated here, to understand the probable usage of these Ca-based chalcopyrite's in optoelectronic applications. The imaginary dielectric tensors are presented and explained in terms of inter-band transitions. The integrated absorption coefficients are calculated to interpret the absorption spectra of all studied compounds.