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

•The dielectric functions of InxAl1-xAs were represented analytically.•We report the parameters needed to calculate ε for arbitrary In-composition.•These results will be useful for in-situ monitoring and designing devices.

We report analytic expressions that accurately represent the dielectric functions ε = ε1 + iε2 of InxAl1−xAs from 1.5 to 6 eV. We use the dielectric function parametric model, which portrays ε as a sum of polynomials and can accommodate the asymmetric nature of critical-point transitions. The ε spectra were obtained previously by spectroscopic ellipsometry for compositions x = 0, 0.10, 0.43, 0.62, 0.75, and 1. The ε data are successfully reconstructed and parameterized in excellent agreement with the data by seven polynomials. Our results allow ε to be determined as a continuous function of In composition and energy over the ranges given above, and ε can be converted to the complex refractive index using a simple relationship.