Spectroscopic ellipsometry study of GaAs 1 − x Bi x material grownon GaAs substrate by atmospheric pressure metal-organicvapor-phase epitaxy

The optical properties in terms of complex dielectric function of GaAs 1 − x Bi x 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 GaAs 1 − x Bi x alloys E 0 transition, the bismuth incorporation shifts the E 1 , E 1 + Δ 1 , E 2 , and E 0 ′ transition energies but with a lower magnitude. We also observed a root-square-like increase of the E 1 broadening parameter ( Γ 1 ) with respect to the bismuth composition.