Peculiarities of deposition times on gas sensing behaviour of vanadium oxide thin films

The importance of vanadium oxide in solid state science as a semiconductor encouraged us to prepare and investigate its microstructure and surface properties related to gas sensing characteristics. Hence, vanadium oxide thin films were deposited by spray pyrolysis method. The prepared films were placed in an electric circuit and the sensing characteristics of these films to ethanol vapors were studied. It was possible to find correlations between nanostructure and electrical properties of the obtained thin films and to optimize conditions of its synthesis. By X-ray diffraction, field emission scanning electron microscopy, and atomic force microscopy, the structure of the deposited films was determined. Based on atomic force microscopy results, the fractal analysis showed a decreasing trend of the fractal dimension (the slope of the log (perimeter) vs. log (area)) versus the deposition time. It was found that the film growth and gas response were affected by the deposition time. The operating temperature of the sensor was optimized for the best gas response. In accordance with our findings, the film deposited at the lowest deposition time (20 min) had the highest sensing response to ethanol.