Abstract:
Tin selenide thin films were prepared by spray pyrolysis technique using tin (II) chloride and selenourea as a precursor compounds using Se:Sn atomic ratio of 1:1 in the starting solution onto glass substrates. Deposition process was carried out in the substrate temperature range of 250 degrees C-400 degrees C using 1 ml/min flow rate. The films were investigated using X-ray diffraction, field emission scanning electron microscopy, Raman spectroscopy, optical absorption and thermoelectric studies. The X-ray diffraction patterns suggest that the major phase is hexagonal-SnSe2 was present when the deposition was carried out in 275 -375 degrees C temperature range, while for the films deposited in the below and above to this range, Sri and Se precipitates into some impure and mixed phase. Raman scattering analysis allowed the assignment of peaks at similar to 180 cm(-1) to the hexagonal-SnSe2 phase. The optical absorption study shows that the direct band gap of the film decreases with increase in substrate temperature and increasing crystallite size. The thermo-electrical measurements have shown n-type conductivity in as deposited films and the magnitude of thermo EMF for films has been found to be increasing with increasing deposition temperature, except for 350 degrees C sample. 350 degrees C deposited samples shows enhance thermoelectric value as compared to other samples. Thermoelectric study reveal that although sample deposited between 275 degrees C and 375 degrees C are structurally same but 350 degrees C sample is thermoelectrically best. (C) 2015 Elsevier B.V. All rights reserved.