Application of Plasma-Films from Tetramethyltin to Gas Sensor Devices

An application of plasma-films plasma-polymerized from tetramethyltin to gas sensor devices was examined. The electrical surface-resistance of these films decreased when exposed to an atmosphere containing propane gas. The magnitudes of the decrease could be enhanced by heat-treatment of these films before measuring and by heating the devices during measuring. Under conditions where the heat-treatment temperature was 300°C-400°C and the measuring temperature was 300°C, the Ralr/Rgas ratio, where Rslr and Rgas, were the electrical resistance in air and propane atmosphere, respectively, was linearly proportional to the propane concentration from 100 to 5000 ppm C3H3. The chemical composition of these plasma-films was analyzed by infrared spectroscopy and ESCA; they are mainly composed of SnO2 with some carbon and hydrogen atoms.