Optical Properties of PbTe

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Abstract
The real (ε 1) and imaginary (ε 2) parts of the dielectric function, ε(E)=ε 1(E)+ iε 2(E), of PbTe have been measured by spectroscopic ellipsometry (SE) in the 1.15–5.4 eV photon-energy range at room temperature. The measured SE spectra reveal distinct structures at energies of E 1, E 2 and E 3 critical points. These data are analyzed using two theoretical models, namely, the model dielectric function (MDF) and standard critical-point (SCP) model. It is found that the SCP model can provide a satisfactory fit to the second derivatives of ε(E) spectra [ d2 ε(E)/ dE 2], but does not yield good fits to ε(E) spectra. The MDF, on the other hand, results in excellent agreement with the experimental data for both ε(E) spectra and their derivatives. Dielectric-related optical constants, such as the complex refractive index (n *=n+ ik), absorption coefficient (α) and normal-incidence reflectivity (R), of PbTe are also presented.