Synthesis of nano-structured tin oxide thin films with faster response to LPG and ammonia by spray pyrolysis

Abstract

Nanostructured SnO2 thin film have been efficiently fabricated by spray pyrolysis using atomizers of different types. The structure and morphology of as-prepared samples are investigated by techniques such as x-ray diffraction, and field-emission scanning electron microscopy. Significant morphological changes are observed in films by modifying the precursor atomization as a result of change of spray device. The optical characterization indicates that change in atomization, affects the absorbance and the band gap, following the varied crystallite size. Gas sensing investigations on ultrasonically prepared tin oxide films show NH3 response at operating temperatures lower down to 50 °C. For 1000 ppm of LPG the response at 350 °C for air blast atomizer film is about 99%, with short response and recovery times. The photoluminescence emmision spectra reveal the correlation between atomization process and the quantity of oxygen vacancies present in the samples. The favorable size reduction in microstructure with good crystallinity with slight change in lattice properties suggest their scope in gas sensing applications. On the basis of these characterizations, the mechanism of LPG and NH3 gas sensing of nanostructured SnO2 thin films has been proposed.