Influence of selenium doping on structural, morphological and thermoelectric properties of nanocrystalline PbTe_100−xSe_x thin films

Nanocrystalline PbTe_100−xSe_x thin films are prepared using an integrated physical–chemical approach by evaporating chemically synthesized PbTe nanopowders on glass substrates. All the deposited films exhibiting the face centered cubic structure with the crystallite orientation along (200) direction. The crystallite size of the films is within the range 10–26 nm. XRD analysis indicated that the lattice constants of PbTe_100−xSe_x thin films decreased with the increasing amount of Se. Raman spectra of these PbTe_100−xSe_x thin films show a wavelength shift in the peak position as compared with PbTe due to the addition of Se in PbTe. Electrical resistivity study reveals that the samples are exhibiting semiconducting nature. The value of the Seebeck coefficient of PbTe_100−xSe_x thin films with x = 0, 6, 10 and 15 is 788, 1101, 921 and 780 µV/K respectively which is high compared to the bulk (265 µV/K). Observed results imply that the thermoelectric properties of PbTe gets enhanced due to doping of Se.