Comparison of CO-gas sensing characteristics between mono- and multi-layerPt/SnO2 thin films

Sensing characteristics of Pt/SnO2 thin composite films to CO gas were inve stigated. The composite films were fabricated by rf magnetron sputtering te chnique. Surface morphology of Pt/SnO2 film was modified to improve its sen sitivity to CO gas. The SnO2 films on which Pt was deposited for 12 s showe d the maximum sensitivity (R-air/R-CO = 1.23 to CO gas of 200 ppm) at the s ensor operation temperature of 175 degreesC. To increase the sensitivity hi gher, multi-layer Pt/SnO2 films was suggested in this work. The multi-layer Pt/SnO2 film was prepared by depositing SnO2 and Pt cluster layers again o n the mono-layer Pt (12 s)/SnO2 film. Compared with SnO2 films on which onl y one Pt layer deposited, multi-layer films exhibited remarkable improvemen t of sensitivity to CO gas (R-air/R-CO = 1.72 to CO gas of 200 ppm). The in crease of the interface area between Pt and SnO2 was reasoned for the super ior GO-sensitivity of the multi-layer film. (C) 2001 Elsevier Science B.V. All rights reserved.