Optical properties of novel ASiP2 (A=Ca, Sr) chalcopyrites: first-principle study

Abstract

We report the electronic and optical properties of the novel ternary ASiP2 (A = Ca, Sr) compounds calculated using the density functional theory (DFT) based on the full potential linearized augmented plane wave (FP-LAPW) method. We calculated the optimized lattice constants (a and c) for both the compounds. The optimized lattice constants were used to calculate the energy band gap and all the optical propeties. The ASiP2 (A=Ca, Sr) chalcopyrites demonstrate the semiconducting behavior with the direct band gap values of 0.97 eV and 0.22 eV in the H–H symmetry direction for CaSiP2 and SrSiP2, respectively. The band gap decreases when Ca is replaced by Sr. There are no experimental results to compare our predicted results. The spectroscopic properties such as total density of states and partial density of states have been discussed in detail. The optical properties such as dielectric function, refractive index, absorption coefficient and optical conductivity were calculated. The predicted results are reported for the first time. Optical properties and the direct band gap of these compounds in the visible region of the electromagnetic energy spectrum ensure their applications in optoelectronic devices.