Effect of substrate temperature on the properties of SnS2 thin films

Tin disulfide (SnS2) thin films deposited on glass substrates at various substrate temperatures 300, 325, 350 and 375 degrees C by the spray pyrolysis technique. Evolutions of the microstructure, surface morphology, optical and electrical properties of the SnS2 thin films as a function of substrate temperature were analyzed. X-ray diffraction (XRD) showed that the deposited films on the T-S < 350 degrees C have a mixture of phase SnS2 and Sn2S3, while those prepared at Ts >= 350 degrees C exhibited the formation just the pure SnS2 phase with hexagonal structure. The mean crystallite size increased from 5.18 to 15.59 nm with increasing substrate temperature from 300 to 350 degrees C. The morphologies of SnS2 films were significantly affected by the substrate temperature. The optical band gap energy varies from 2.55 to 1.82 eV with the substrate temperatures. Film thickness (d) and optical constants such as refractive index (n), extinction coefficient (k) and dielectric constant (epsilon) were obtained with the seed preprocessing Pattern search (spPS) technique. Using the measured absorption coefficient data, we estimated the expected absorption capacity and photocurrent of the SnS2 thin films. The photocurrent density J(ph) was found to be 33 mA/cm(2) for Ts >= 350 degrees C. Hall Effect measurements confirm the n-type nature of the as-deposited thin films. The resistivity of the SnS2 thin films decreased from 1.12 x 10(+2) to 2.74 x 10(-2) Omega.cm as the substrate temperature increased from 300 to 350 degrees C due to the increased carrier concentration and Hall mobility.