Modeling the optical constants of Al xGa 1-xAs alloys

Abstract

Extension of Adachi's model with a Gaussian-like broadening function instead of a Lorentzian one is used to model the optical dielectric function of the alloy Al xGa 1-xAs. Gaussian-like broadening is accomplished by replacing the damping constant in the Lorentzian line shape with a frequency dependent expression. In such a manner, the comparative simplicity of analytic formulae of the model is preserved, while the accuracy becomes comparable to more intricate models, and/or models with a significantly greater number of parameters. The employed model describes accurately the optical dielectric function in the spectral range from 1.5 to 6.0 eV in the entire alloy composition range. Relative rms error obtained for the refractive index is below 2.2% for all compositions.