Synthesis, characterization and gas sensing performance of SnO2 thin films prepared by spray pyrolysis

In this work, SnO2 thin films were deposited onto alumina substrates at 350 degrees C by spray pyrolysis technique. The films were studied after annealing in air at temperatures 550 degrees C, 750 degrees C and 950 degrees C for 30 min. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical absorption spectroscopy technique. The grain size was observed to increase with the increase in annealing temperature. Absorbance spectra were taken to examine the optical properties and bandgap energy was observed to decrease with the increase in annealing temperature. These films were tested in various gases at different operating temperatures ranging from 50-450 degrees C. The film showed maximum sensitivity to H2S gas. The H2S sensing properties of the SnO2 films were investigated with different annealing temperatures and H2S gas concentrations. It was found that the annealing temperature significantly affects the sensitivity of the SnO2 to the H2S. The sensitivity was found to be maximum for the film annealed at temperature 950 degrees C at an operating temperature of 100 degrees C. The quick response and fast recovery are the main features of this film. The effect of annealing temperature on the optical, structural, morphological and gas sensing properties of the films were studied and discussed.