Thin film SnO/sub 2/-based gas sensors fabricated using sol-gel method for the detection of ethanol

Thin films of SnO/sub 2/ were prepared by a sol-gel technique using tin tetrachloride (SnCl/sub 4/) and isopropyl alcohol solution. Applying standard lithography process, high sensitivity SnO/sub 2/ gas sensors were miniaturized on macromachined Si(100) substrates. Conductivity measurements of the films annealed at different temperatures have been carried out in dry air and in the presence of 5 ppm to 100 ppm ethanol. Response and recovery times of the sensors annealed at 550/spl deg/C at the optimum operating temperature were found to be about 5 and 40 seconds, respectively. Also sensitivity of the sensors was studied towards 500 ppm CO and 1000 ppm H/sub 2/ at different temperatures, indicating the satisfactory selectivity for ethanol.