Hydrogen gas sensing based on nanocrystalline SnO2 thin films operating at low temperatures

Abstract

Nanocrystalline (NC) SnO2 thin film has been prepared using sol-gel technique on Al2O3 substrates at low temperature. X-ray diffraction emerged that SnO2 thin film reveals the crystalline nature of NC SnO2 with a tetragonal rutile structure. Field emission scanning electron microscopy image emerged that the morphology of SnO2 thin film is uniform structure a polycrystalline. Hydrogen (H2) gas sensing measurements were performed when the sensor exposed to very low H2 concentration levels in the range 3–100 ppm at operating temperatures ranging from room temperature up to 125 °C. The NC SnO2 thin film sensor was found to be active for H2 sensing, with high sensitivity (48%, 3 ppm and 180%, 100 ppm) respectively at room temperature. Moreover, the sensitivity of the sensor increased with increasing operating temperature, where the sensitivity value at 125 °C (902%, 3 ppm and 3475%, 100 ppm) of H2 gas respectively. The obtained values were significantly higher as compared to the results in the literature. These findings attributed to increasing adsorption/desorption processes of gas molecules that lead to improving sensing properties of a gas sensor.