Spectroscopic ellipsometry study of Pb1-xEuxSe(0 <= x <= 0.45)

We have measured the complex dielectric function, epsilon(E)=epsilon(1)(E)i epsilon(2)(E), of Pb1-xEuxSe in the 1.2-5.0 eV photon-energy range by spe ctroscopic ellipsometry at room temperature. The Pb1-xEuxSe crystals were g rown by the conventional Bridgman method (x=0) and by hot-wall epitaxy on ( 111) BaF2 substrates at 300 degrees C (0.09 less than or equal to x less th an or equal to 0.45). The measured epsilon(E) data revealed distinct struct ures at two critical-point (CP) energies, E-1 and E-2. The second-derivativ e spectra of the complex dielectric function, d(2)epsilon(E)/dE(2), were an alyzed using a theoretical model called the model dielectric function. The CP parameters, such as the CP energy, amplitude, and broadening, as a funct ion of alloy composition x were fit determined from these derivative analys es. This parameterization of the CP parameters enabled us to calculate epsi lon(E) and its related optical constants for optional alloy composition and photon energy. (C) 1999 American Institute of Physics. [S0021-8979(99)0641 7-8].