Spectroscopic ellipsometry study of Pb1−xEuxSe(0⩽x⩽0.45)

Abstract

We have measured the complex dielectric function, ε(E)=ε1(E)+iε2(E), of Pb1−xEuxSe in the 1.2–5.0 eV photon-energy range by spectroscopic ellipsometry at room temperature. The Pb1−xEuxSe crystals were grown by the conventional Bridgman method (x=0) and by hot-wall epitaxy on (111) BaF2 substrates at 300 °C (0.09⩽x⩽0.45). The measured ε(E) data revealed distinct structures at two critical-point (CP) energies, E1 and E2. The second-derivative spectra of the complex dielectric function, d2ε(E)/dE2, were analyzed using a theoretical model called the model dielectric function. The CP parameters, such as the CP energy, amplitude, and broadening, as a function of alloy composition x were fit determined from these derivative analyses. This parameterization of the CP parameters enabled us to calculate ε(E) and its related optical constants for optional alloy composition and photon energy.