Characterization and NO2 gas sensing properties of spray pyrolyzed SnO2 thin films

The nanocrystalline tin oxide (SnO2) thin films were synthesized with varing precursor concentrations of the solution by spray pyrolysis technique for NO2 gas detection. The structural, morphological, optical and electrical properties of nanocrystalline SnO2 films were studied with XRD, SEM, UV-visible and two probe resistivity measurement setup. The XRD analysis shows SnO2 thin film has tetragonal rutile structure. From XRD analysis the crystallite size and dislocation density were determined by considering the full width at half maximum (FWHM) from the diffracted peaks. The crystallite size and dislocation density were varies between 4.796 run to 11.563 nm and 7.484 x 10(15) lines/m(2) to 43.592 x 10(15) lines/m(2) respectively, while optical band gap energy found in the range of 3.40 eV to 4.06 eV. The gas sensing properties were studied using indigenously built gas sensing unit. The gas response of NO2 gas at 150 degrees C optimized operating temperature for 40 ppm is found to be 556, with recovery and response time is 48 s to 224 s and 100 s to 46 s respectively.