Parameterization of the dielectric function of InxAl1−xAs alloys as a function of composition

Abstract We report analytic expressions that accurately represent the dielectric functions e  =  e 1  +  ie 2 of In x Al 1− x As from 1.5 to 6 eV. We use the dielectric function parametric model, which portrays e as a sum of polynomials and can accommodate the asymmetric nature of critical-point transitions. The e spectra were obtained previously by spectroscopic ellipsometry for compositions x  = 0, 0.10, 0.43, 0.62, 0.75, and 1. The e data are successfully reconstructed and parameterized in excellent agreement with the data by seven polynomials. Our results allow e to be determined as a continuous function of In composition and energy over the ranges given above, and e can be converted to the complex refractive index using a simple relationship.