Characterization of Tin disulphide thin films prepared at different substrate temperature using spray pyrolysis technique

Thin films of tin disulphide on glass substrates were prepared by spray pyrolysis technique using precursor solutions of SnCl₂·2H₂O and n–n dimethyl thiourea at different substrate temperatures varied in the range 348–423 K. Using the hot probe technique the type of conductivity is found to be n type. X ray diffraction analysis revealed the polycrystalline nature with increasing crystallinity with respect to substrate temperature. The preferential orientation growth of SnS₂ compound having hexagonal structure along (002) plane increased with the substrate temperature. The size of the tin disulphide crystallites with nano dimension were determined using the Full Width Half Maximum values of the Bragg peaks and found to increase with the substrate temperature. The surface morphology had been observed on the surface of these films using scanning electron microscope. The optical absorption and transmittance spectra have been recorded for these films in the wavelength range 400–800 nm. Thickness of these films was found using surface roughness profilometer. The absorption coefficient (α) was determined for all the films. Direct band gap values were found to exist in all the films deposited at different substrate temperatures. The value of room temperature resistivity in dark decreased from 5.95 × 10³ Ω cm for the amorphous film deposited at low temperature (348 K) to 2.22 × 10³ Ω cm for the polycrystalline film deposited at high temperature (423 K) whereas the resistivity values in light decreased from 1.48 × 10³ to 0.55 × 10³ Ω cm respectively, which is determined using the four probe method. Activation energy of these thin films was determined by Arrhenius plot.