Resumen de Structural, electronic and optical properties of the wide band gap semiconductors KGaQ_(2) (Q = S, Se) and of AGaTe_(2) (A = K, Cs)
N. Benmekideche, S. Fetah, Gh. Belgoumri, A. Bentabet, A. Benmakhlouf
In this paper, we studied the structural, electronic and some optical properties of KGaQ_(2)(Q = S, Se) and AGaTe_(2)(A = K, Cs) crystals using the pseudopotential plane-wave (PP-PW) method based on density functional theory (DFT), the generalized gradient approximation (GGA) parameterized by Perdew-Burke-Ernzerhof (GGA-PBE) is used for the exchange-correlation (XC) potential. We also use the hybrid density functional (HSE06) to study the electronic structures of these materials. Our results for the equilibrium lattice constants (a, b and c), angle β are in good agreement with experiment data. The electronic structure calculation suggested that crystals are direct-gap semiconductors, employing both the Perdew-Burke-Ernzerhof (PBE) and the hybrid (HSE06) functionals. We note that the hybrid density functional improved the value of band gap, and that the studied compounds are semiconductors with wide band-gaps. We have also predicted the optical properties; the refractive index, the reflection coefficient and dielectric constant on high frequencies.
