FIRST PRINCIPLES CALCULATIONS OF ELECTRONIC AND OPTICAL PROPERTIES OF CuInSe_2 ABSORBER LAYER

摘要

The structural, electronic and optical properties of CuInSe_2 chalcopyrite semiconductors have been computed with the first principles method. We report results from density functional theory (DFT) using the full potential-linearized augmented plane wave (FP-LAPW) method. The local density approximation (LDA), Perdew-Burke-Ernzerhof-generalized gradient approximation (PBE-GGA) and the Engel-Vosko-generalized gradient approximation (EV-GGA) were used for the exchange-correlation energy of the structural, electronic structure and optical properties of CuInSe_2 chalcopyrite semiconductor. EV-GGA results for the band gap of this compound are much better than those obtained using LDA and PBE-GGA approximations. We have found that EV-GGA calculation gives energy gap about 1.152 eV in reasonable agreement with the experiment (1.04 eV). The geometrical parameters such as the lattice parameters and anion displacement are evaluated. Also, electronic properties like band structures and density of states have been studied. Furthermore, the optical properties, real part of the dielectric function, refractive index, reflectivity and absorption coefficients are calculated from the imaginary part of the dielectric function, which are comparable with the experimental data and earlier theoretical results. Our calculations revealed the better results using the EV-GGA kind of exchange-correlation potential on the electronic and optical properties.