Effect of Substrates Types on CO Gas Sensing of SnO2 Thin Film Prepared by Sol-Gel Method

Tin oxide thin film was synthesized on glass and quartz substrate by sol-gel dip coating process taking tin (II) chloride as precursor and methanol as solvent. XRD study confirmed the tetragonal rutile structure of SnO2. It was concluded that the transmission was higher and grain size was bigger in case of quartz than glass substrate from the study of optical characteristics by UV/VIS Spectrophotometer and SEM micrographs. CO gas sensing property of SnO2 thin film was studied and it was revealed that the sensitivity of SnO2 thin film grown on quartz substrate shows better performance than the film grown on glass substrate under the same conditions. Sensitivity of the film to CO gas was measured at different temperatures and was found to be highly sensitive at 220 degrees C for glass substrate and 210 degrees C for quartz substrate, at 50 ppm concentration. The result of change in conductivity of the sensors in presence of CO gas was also reported.