Synthesis of Ag doped SnO2 thin films for the evaluation of H2S gas sensing properties

The Tin Oxide (SnO2) based thin films doped with 1.5, 3.0 and 4.5 mol% of Ag were deposited on the glass substrates using the advanced chemical spray pyrolysis technique. All the films were deposited at temperature 400 degrees C. The crystalline structure of the samples was analyzed by X-ray diffraction (XRD). All the XRD patterns of the films showed a well-defined polycrystalline phase, fitting well with the SnO2 tetragonal rutile type structure. The optical properties of the Ag doped SnO2 films were studied using UV-Visible absorption spectroscopy. The surface morphological analysis of as-synthesized Ag doped SnO2 films have been carried out using scanning electron microscope (SEM). The sensor response was estimated by the change in the electrical resistance of the film in the absence and presence of H2S gas. The sensor response and sensitivity in relation to, operation temperature and the gas concentration have been systematically studied. A significant response (similar to 1.38) and with a short response and recovery time (46 s, 110 s) towards 450 ppm H2S at 100 degrees C operating temperature is observed for the 3 mol% Ag-doped SnO2 film. This method offers a highly promising candidate for development of materials sensors due to facile fabrication route and desirable sensing performance.