Optical Constants of Zn_1-xCd_xTe Ternary Alloys: Experiment and Modeling

Abstract

The optical spectra of Zn 1- x Cd x Te ternary alloys in the 1.1-5.6-eV photon-energy range at room temperature have been measured by spectroscopic ellipsometry (SE). The optical constants reported here are the complex dielectric constant (ε=ε 1 +iε 2 ), complex refractive index ( n * = n +i k ), absorption coefficient (α) and normal-incidence reflectivity ( R ). The measured data are analyzed on the basis of a simplified model of the interband transitions. The experimental data reveal distinct structures in the optical spectra at energies of the E 0 , E 0 +Δ 0 , E 1 , E 1 +Δ 1 and E 2 transitions, and are in reasonable agreement with the theoretical model. The model proposed here enables us to obtain the optical response in Zn 1- x Cd x Te alloys of arbitrary composition ( x ) and photon energy ( E =\hbarω).