الفهرس 
Introduction and Literature reviewOnly 14 pages are availabe for public view
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Abstract
PbS and PbSe nanocrystals play an important role in photovoltaic applications. PbS and PbSe nanomaterials powder have been prepared by hot injection method. PbSxSe1-x (x ranges from 0 to 1) nanocrystalline thin films of different thicknesses and compositions have been prepared by thermal evaporation technique on glass and quartz substrate. The structural, electrical, optical and photoconductivity properties have been investigated for PbS, PbSe and PbSxSe1-x (x ranges from 0 to 1) films.
The structural characterization of PbS and PbSe nanomaterial are studied using X-ray diffraction (XRD) technique. The structure of PbS, PbSe and PbSxSe1-x (x ranges from 0 to 1) films of different thicknesses and compositions are studied using grazing incident X-ray diffraction (GIXRD). The structural analysis shows that PbS and PbSe nanomaterials and thin films have nanocrystalline structure with the cubic (rock salt Fm-3m) structure. The morphology and particle size of PbS and PbSe nanocrystalline films are investigated by transmission electron microscope (TEM). The morphology shows that the films consist of quantum dots. The optical transmittance and reflectance spectra are measured. The optical constants are determined such as the absorption coefficient α, the optical band gap Eg, the refractive index n, the optical dielectric constant ε∞, the ratio between the charge carriers concentration and the effective mass N/m*. It is found that the optical band gap Eg of PbS, PbSe and PbSxSe1-x (x ranges from 0 to 1) films is dependant on the particle size. The electrical resistivity (ρ), the charge carriers concentration (n) and the charge carriers mobility (μ) of PbS, PbSe and PbSxSe1-x (x ranges from 0 to 1) films are determined as a function of temperature using Hall effect experiment. The carriers concentration n of PbS, PbSe and PbSxSe1-x (x ranges from 0 to 1) films are in the order of 1016 cm-3, 1015 cm-3 and 1017 cm-3, respectively. The a.c photoconductivity response spectra of PbS, PbSe and PbSxSe1-x (x ranges from 0 to 1) nanocrystalline thin films were also studied. The spectra of PbS, PbSe films show that photoconductivity response of PbS films have higher energy peaks if compared with those of PbSe. The ternary PbSxSe1-x (x ranges from 0 to 1) nanocrystalline thin films of different compositions have photoconductivity response spectra characterized by one peak for fundamental transition.