Spectroscopic ellipsometry study of GaAs1−xBix material grown on GaAs substrate by atmospheric pressure metal-organic vapor-phase epitaxy

Abstract

The optical properties in terms of complex dielectric function of GaAs1−xBix alloys (0%≤x≤3.7%), grown by atmospheric pressure metal-organic vapor-phase epitaxy, are determined by using room temperature spectroscopic ellipsometry. The interband transition energies in the energy range of 1.4–5.4 eV are resolved using a line shape fitting on the numerically calculated dielectric function second derivatives. The bismuth effect on the critical point parameters is then determined. We have found that, as for GaAs1−xBix alloys E0 transition, the bismuth incorporation shifts the E1, E1+Δ1, E2, and E0′ transition energies but with a lower magnitude. We also observed a root-square-like increase of the E1 broadening parameter (Γ1) with respect to the bismuth composition.