Highly desirable semiconducting materials for mid-IR optoelectronics: Dilute bismide InAs1−xBix alloys

We have performed a self-consistent full-potential linearized augmented plane wave (FP-LAPW) method within density functional theory (DFT) to investigate the structural, electronic and optical properties of the dilute bismide InAs1−xBix alloys (0 ≤ x ≤ 0.125) for mid-IR optoelectronics application. The ground state properties including the lattice constant a0 and bulk modulus B0 are obtained by using Wu-Cohen generalized gradient approximation (WC-GGA), show agreement with experimental data. The calculated band gap energy (Eg) using Tran-Blaha-modified Becke-Johnson scheme (TB-mBJ) with spin-orbit coupling, show close agreement to experimental Eg. InAs1−xBix alloys exhibits large band gap reduction for small Bi compositions (∼380 meV for x = 0.125) covering the mid- and far-IR (∼2.6-14 μm) wavelengths range. The narrow-band gap in InAs1−xBix alloys can be attributed to the both resonant interaction of Bi-p states with the valence band maximum (VBM) and the hybridization (anticrossing) of the unoccupied s/p orbitals of In/As/Bi atoms with the host conduction band (CB). The dielectric functions and optical parametric quantities such as refractive index, extinction coefficient, absorption coefficient, reflectivity and energy loss function are determined for radiation range 0-10 eV in comparison with available experimental data. The critical-point (CP) energies have been identified from the computed electronic band structure in agreement with measured data. This makes InAs1−xBix potential materials for fabrication advanced optoelectronic devices as photodetectors and laser diodes operating in the mid-IR wavelengths region.