Parametrization of the Optical Constants of AlAs_xSb_1-x Alloys in the Range 0.74-6.0 eV

Abstract

We report parameters that allow the dielectric functions ε = ε 1 + iε 2 of AlAs x Sb 1-x alloys to be calculated analytically over the entire composition range 0 ≤ x ≤ 1 in the spectral energy range from 0.74 to 6.0 eV by using the dielectric function parametric model (DFPM). The ε spectra were obtained previously by spectroscopic ellipsometry for x = 0, 0.119, 0.288, 0.681, 0.829, and 1. The ε data are successfully reconstructed and parameterized by six polynomials in excellent agreement with the data. We can determine ε as a continuous function of As composition and energy over the ranges given above, and ε can be converted to complex refractive indices using a simple relationship. We expect these results to be useful for the design of optoelectronic devices and also for in situ monitoring of AlAsSb film growth.