Spectroscopic ellipsometric study of Cd1-xFexTe single crystals

The complex dielectric function of Cd1-xFexTe (x=0, 0.02, and 0.04) single crystals were measured by spectroscopic ellipsometry in the 1.5 similar to 4.5 eV photon energy range at room temperature. The measured epsilon(omega) data revealed distinct structures at energies of the E-1 and E-1 + Delta(1 ) critical points (CPs). These data were analyzed by fitting the second-der ivative spectra (d(2)epsilon/d omega(2)) with a. theoretical model, i.e., t he standard critical point (SCP) line shapes. It was found that the SCP mod el explained the measured derivative spectra successfully. The CP energies and the Lorentzian broadening(Gamma) were determined.