Temperature Dependence of the Spectra of Optical Constants of CdTe in the Region of the Absorption Edge

Abstract

In this work, the spectra of optical constants of epitaxial layers of cadmium telluride near the fundamental absorption edge are studied. For this purpose, ellipsometric measurements of the layers under study were carried out in a vacuum chamber in the temperature range from T = 38–275°C. A numerical algorithm has been developed for solving the inverse ellipsometry problem for the structures under consideration, with the help of which the spectral dependences of the refractive index n(λ) and absorption index k(λ) are determined in the wavelength range from 700 to 1000 nm. The parametric dependences of k(λ, T) in the fundamental absorption region and in the transparency region are presented. The presence of an extended absorption tail in the transparency region was established, presumably associated with imperfections in the crystal structure.