First-principle study of the optoelectronic properties of GaxIn1-xBiyP1-y quaternary alloys lattice-matched to InP for telecommunication applications

In this work, we present a theoretical investigation of the structural and optoelectronic properties of GaxIn1-xBiyP1-y quaternary alloys lattice-matched to InP using the full-potential linearized augmented plane wave approach based on the functional theory of density. The local density approximation (LDA) and the generalized gradient approximation of Wu-Cohen (WC-GGA) have been used for calculating the structural properties of GaxIn1-xBiyP1-y quaternaries. The lattice matching condition and the range of (x, y) concentrations for which the quaternary alloys are lattice-matched to InP substrate were determined. It is found that the calculated lattice constants of GaxIn1-xBiyP1-y for all selected concentrations (x, y) are about 5.9 A, which are in good agreement with the experimental value of the lattice constant of InP (5.869 A). The electronic property calculations are executed via EV-GGA and TB-mBJ approximations. The calculated band structures show that GaxIn1-xBiyP1-y quaternaries have semiconductor character and exhibit a direct band gap, for all selected concentrations (x, y). In addition, the optical properties were calculated and discussed in detail. And also, the optical band gaps of quaternaries were determined using Tauc's method. We observed that the GaxIn1-xBiyP1-y quaternaries cover the wavelength ranging from 0.911 to 2.456 & mu;m while maintaining a lattice match to the InP substrate. The obtained results reveal that these quaternaries are suitable candidates for telecommunication applications.