Improved stability of gas sensor by inclusion of Sb in nanostructured SnO2 thin films grown on sodalime

Abstract In the present work an attempt has been made to improve the stability in the oxygen gas sensing property of SnO2 with Sb doping using low cost sol-gel spin coating techniques. Un-doped and Sb (0, 0.5, 1.0, 1.5 and 2 at. %) doped SnO2 thin films were deposited on sodalime glass substrate by spin coating technique at 2500 rpm and annealed at 400 °C. The properties of thin films were investigated by their structural, morphological, optical and electrical analysis for for oxygen gas sensing at low operating temperature. The crystalline phase and crystallite size were measured by X-ray diffraction pattern. It was observed that peaks show the polycrystalline nature with the tetragonal crystal structure. Scanning electron microscopic images revealed that all thin films have spherical type morphology. The transmittance spectra were recorded in the wavelength range 200–800 nm and optical band gap was varied from 3.56 eV to 3.92 eV with increasing doping concertation. The I–V measurements were recorded from −5 V to 5 V by two probe method. The highest conductivity was observed for 1 at. % Sb doped SnO2 thin film sample. The gas sensing properties of above thin films were measured as a function of operating temperature in the temperature range from 30 °C to 125 °C and the highest response was obtained for 1 at. % Sb doped SnO2 thin film sample. It has been observed from the experimental results that Sb doped SnO2 thin films exhibit the improved gas response, low operating temperature and good selectivity.