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 E-0 transition, the bismuth incorporation shifts the E-1, E-1 + Delta(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 (Gamma(1)) with respect to the bismuth composition. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3167359]