Study of Optical Properties of Co-evaporated PbSe Thin Films

Thin films of Lead Selenide (PbSe) of thicknesses ranging from 1050 A to 5500 A have been prepared by co-evaporation technique, onto precleaned amorphous glass substrates. The deposited samples were annealed and annealed samples were used for characterization. The XRD analysis confirms that lead selenide films are polycrystalline having cubic structure. The lattice parameters of thin films are almost matching with ASTM data for lead selenide. The transmittance and reflectance have been measured at normal incidence in the spectral range (200-2600 nm). The dependence of adsorption coefficient,
on photon energy have been determined. Analysis of result showed that for co-evaporated PbSe films of different thicknesses direct transition occurs with band gap energies in the range 1.08 eV to 1.54 eV. Refractive indices and extinction coefficients have been evaluated in the above spectral range.