Effect of thermal-oxidized tin black filter on SnO2 gas sensors

Two different sensors were prepared with and without an oxidized tin black filter, and then the effect of the filter on detecting the properties of hydrocarbon gases was investigated. The oxidized tin black filter was prepared by Sn thermal evaporation in a low vacuum, Ar atmosphere of 0.6 Torr. Thereafter, the tin black film was oxidized at an operating temperature of 600 °C to maximize the chemical filtering effect. The SnO2 sensing layer under the filter was prepared by the thermal oxidation of metallic tin film with a 2000 إ thickness. Morphologically, the oxidized tin black filter exhibited a high porous and foam structure. The addition of a filter to the tin oxide sensing layer had a positive effect on the selectivity towards CH4 in comparison with iso-C4H10 and C3H8.