Understanding the structural, electronic and optical properties of CuXY2 (X = Si, Ge, Y = P, As): A DFT +U approach

Abstract

In this study, the structural, electronic and optical properties of CuXY2 (X = Si, Ge, Y = P, As) materials were computed via first-principles DFT calculations. The obtained results are quite consistent with the experimental data and previous theoretical data. CuSiP2, CuSiAs2, CuGeP2 and CuGeAs2 are direct and narrow band gap semiconductors with band gap energies of 0.80 eV, 0.62 eV, 0.53 eV and 0.35 eV, respectively. In the upper and lower bands, the s, p and d atomic orbitals were the main contributors. The s, p and d bonding orbitals contributed substantially to the total and partial density of states in the formation of the valence band and conduction band. The electronic charge density revealed that the bonding nature was a mixture of covalent and ionic bonds. The optical features of these materials were studied and discussed in terms of the dielectric function, refractive index, optical conductivity, reflectivity and loss function. The high reflectivity and direct band gap of these compounds in the ultraviolet and visible ranges of electromagnetic energy (photon) revealed the potential utilization of these materials in optoelectronic applications.