Contactless electroreflectance and theoretical studies of band gap and spin-orbit splitting in InP_1−xBi_x dilute bismide with x ≤ 0.034

Contactless electroreflectance is applied to study the band gap (E₀) and spin-orbit splitting (Δ_SO) in InP_1−xBi_x alloys with 0 < x ≤ 0.034. The E₀ transition shifts to longer wavelengths very significantly (−83 meV/% Bi), while the E₀ + Δ_SO transition shifts very weakly (−13 meV/% Bi) with the rise of Bi concentration. These changes in energies of optical transitions are discussed in the context of the valence band anticrossing model and ab initio calculations. Shifts of E₀ and E₀ + Δ_SO transitions, obtained within ab-initio calculations, are −106 and −20 meV per % Bi, respectively, which is in a good agreement with experimental results.