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

We report analytic expressions that accurately represent the dielectric functions epsilon = epsilon(1) + i epsilon(2) of InxAl1-xAs from 1.5 to 6 eV. We use the dielectric function parametric model, which portrays epsilon as a sum of polynomials and can accommodate the asymmetric nature of critical-point transitions. The epsilon spectra were obtained previously by spectroscopic ellipsometry for compositions x = 0, 0.10, 0.43, 0.62, 0.75, and 1. The epsilon data are successfully reconstructed and parameterized in excellent agreement with the data by seven polynomials. Our results allow epsilon to be determined as a continuous function of In composition and energy over the ranges given above, and epsilon can be converted to the complex refractive index using a simple relationship. (C) 2015 Elsevier B.V. All rights reserved.