Structural and optical characterization of laser-deposited PbTe films on silicon substrates

The structural and optical properties of PbTe films, fabricated using pulsed laser evaporation, are studied. The grazing incident asymmetric X-ray diffraction patterns, obtained at different grazing angles, unambiguously demonstrate that the films represent three-layered structures. Each of the layers is of one of the competitive PbTe phases-the metastable CsCl-type, the metastable GeS-type and the stable NaCl-type crystal modifications. The CsCl-type phase lattice parameter and layer thickness in the films grown on Si substrates are compared with those in the films grown on substrates with the NaCl-type structure. The energy dependence of the refractive index was obtained from the extrema of the interference fringes in the transmittance and reflectance spectra. The dependence can be interpreted by treating the films as three-layered structures with a different crystal modification of each of the layers. (C) 2002 Elsevier Science Ltd. All rights reserved.