A density functional theory investigation of the structural and optoelectronic properties of InP1−xBix alloys

Abstract

In this work, we report a theoretical investigation of the structural, electronic and optical properties of InP1−xBix alloys. The study has been carried out by varying up the fraction x from 0 to 0.375. The calculations are performed using the density functional theory (DFT). The full potential linearized augmented plane wave (FPLAPW) scheme, as implemented in Wien2k package, is employed. The modified Becke-Johson potential with local density approximation (mBJLDA), which combines the Becke-Johson exchange potential with the local density approximation correlation potential, is used to evaluate the alloys band structure. We have studied the effect of bismuth composition on the structural and optoelectronic proprieties and found that lattice parameter of the compound increases with the bismuth composition which is in good agreement with Vegard’s law. A band gap reduction of the order 36 meV/%Bi with the Bi composition is observed giving rise to a semi-metallic behaviour beyond a composition about 47%. The effective masses of the binary compound InP and InP1−xBix alloys obtained, by our calculations, are in good agreement with the experimental results. Furthermore, the effects of the bismuth concentration on the dielectric function of the alloys is elucidated, suggesting that dopage of bismuth tunes the electronic and optical properties of the InP matrix. In addition, the calculated low value of the reflectivity in the visible and UV region of the InPBi alloys, together with the consistent behavior of the band gap and the reflective index variations with the composition of bismuth overall experimental results, shed light on the candidacy of InP1−xBix alloys as potential material for optoelectronic applications.