First-principles calculations of the structural and optoelectronic properties of BSb1−x Asx ternary alloys in zinc blende structure

Abstract

In this work, we studied the structural and optoelectronics properties of BSb1−xAsx ternary alloys in zinc blende structure. BSb1−x Asx’s properties were calculated by employing the full-potential linearized augmented plane wave (FP-LAPW) formalism based on density functional theory (DFT). 16-atoms special quasi-random structures (SQS) are used to describe the disordered ternary alloys. The local density approximation (LDA) and both generalized gradient approximation (GGA) of Wu and Cohen (GGA-WC) and of Perdue et al. (GGA-PBEsol) have been used to calculate the structural properties. The obtained structural parameters of BSb1−xAsx are compared to available data reported in the literature. Our calculations show that the result obtained of lattice parameter with (GGA-PBEsol) approach is better than the (LDA), (GGA-WC). It is found that the variation of the lattice constant a(x) exhibits a small bowing parameter according to Vigard’s law. The optoelectronic properties were computed using the (LDA), (GGA-WC), (GGA-PBEsol) and (TB-mBJ) approximations. The calculated band gaps with the (TB-mBJ) approach are better than obtained by (LDA), (GGA-WC), (GGA-PBEsol) approximations. Our obtained value of band gap for BAs is in good agreement with the experimental data while for BSb a disagreement has been observed between our calculated value and the experimental value. Electronic band structure shows that BSb1−xAsx ternary alloys have an indirect band gap, for all arsenic concentrations (0 ≤ x ≤ 1). We observed that the incorporation of As into BSb leads to the reduction of the lattice constant a(x) and to the increase of the band gap Eg(x). In addition, both parts of dielectric function, absorption coefficient, conductivity optic, reflectivity, loss function, refractive index and extinction coefficient have been discussed.