In this paper, tin oxide, SnO2, thin films were coated on soda- lime glass substrates using the simple and economic processing route such as dip coating sol- gel method. In the preparation of a stable sol, instead of using only one alcohol, a combination of some alcohols without adding any surfactant and applying non- liquid tin chloride has been used. The effect of temperature, time, and thickness of the layers were studied. The phase and structural determination of samples were obtained by X-ray diffraction (XRD) analysis. Scanning electron microscopy (SEM) images were used for size and morphological evaluation of the thin films obtained. The gas- sensor response of tin dioxide thin films was determined by electrical sheet resistance measurements. After exposing the gas to different concentrations of ethanol, the effects of temperature, gas concentration, size, shape, dispersion of crystallite and thickness of the film on the sensor response were investigated. The best sensing responses are related to a two- times deposited layer with a thickness of about 299 nm heated at 400 οC and 600 οC. The first detection of gas concentration was at about 27.7 ppm ethanol at 300 οC. Also, the level of response and recovery times of this sensor were 70 and 88 s, respectively.

Keywords: Sol-gel, Gas sensor, Tin oxide, Ethanol, Dip coating, Thin film.