Gas Sensing Characteristics of WO3-Doped SnO2 Thin Films Prepared by Solution Deposition Method

WO3-doped SnO2 thin films were prepared in a solution-deposition method and their gas-sensing characteristics were investigated. The doping of WO3 to SnO2 increased the response (Ra/Rg, Ra: resistance in air, Rg: resistance in gas) to H-2 substantially. Moreover, the Ra/Rg value of 10 ppm CO increased to 5.65, whereas that of NO2 did not change by a significant amount. The enhanced response to H-2 and the selective detection of CO in the presence of NO2 were explained in relation to the change in the surface reaction by the addition of WO3. The WO3-doped SnO2 sensor can be used with the application of a H-2 sensor for vehicles that utilize fuel cells and as an air quality sensor to detect CO-containing exhaust gases emitted from gasoline engines.