Electronic and optical properties of GaInX2 (X=As, P) from first principles study

The structural, electronic and optical properties of GaInAs2 and GaInP2 with chalcopyrite structure in ternaries compounds have been studied in the present paper. To obtain accurate results, we have based our research on three phases. In the first phase, we used the first-principles calculations by using the full potential-linearized augmented plane wave method (FP-LAPW) within the density functional theory (DFT). In the second phase, the structural properties as exchange-correlation potential, the generalized gradient approximation (GGA-PBE Sol) of Perdew and al and local density approximation (LDA) of Perdew and Wang have been used. And in phase three, in order to get best values of the band gap, we used the developed form of GGA proposed by Engel-Vosko (EV-GGA) and the modified Becke-Johnson (mBJ) of Tran and Blaha, which are based on the optimization of total energy and corresponding potential. The compounds of GaInP2 and GaInAs2 demonstrate semiconducting behaviour with the direct-band gap of 0.3 and 2.03 eV using rnBJ approach. The dielectric function, refractive index, reflectivity, absorption coefficient have been studied and the optical conductivity functions are calculated for radiation up to 20 eV. The obtained results indicate that GaInP2 and GaInAs2 are attractive materials for optoelectronic and photovoltaic applications.