Improved response characteristics of SnO2 thin film loaded with nanoscale catalysts for LPG detection

This paper reports the response characteristics of rf-sputtered SnO2 thin films (90 nm thick) loaded with nanoscale catalysts for LPG detection. Ultrathin (8 nm) layers of various metal catalysts (Pt, Ag, Ni, Ph) and their respective oxides are loaded over the SnO2 surface in the form of dotted islands. All sensor structures prepared with catalysts show higher sensor resistance in air and are attributed to the difference in the work function of the metal catalysts with respect to the underneath SnO2 layer. A SnO2 film with Pt-dotted islands is found to exhibit an enhanced response of about 750 for 100 ppm of LPG at a relatively low operating temperature (260 degrees C) with a fast response time of 100s. The high response is shown to be primarily due to dominant roles played by both Fermi energy control mechanism and spillover mechanism. The results suggest the possibility of utilizing the sensor structure having novel dispersal of Pt catalyst on the SnO2 film surface for efficient detection of LPG. (c) 2008 Elsevier B.V. All rights reserved.