DILUTE HYDROGEN-SULFIDE SENSING PROPERTIES OF CUO-SNO2 THIN-FILM PREPARED BY LOW-PRESSURE EVAPORATION METHOD

A low pressure evaporation method was adopted for preparing SnO2 and C uO-SnO2 thin films. Metallic tin and copper were evaporated on the alu mina substrate under a low pressure (1 torr) of air atmosphere. As obs erved with AFM, these evaporated films had unique microstructure in wh ich discrete clusters of SnO2 grains (30 nm) contacted to each other t wo-dimensionally with large mesopores penetrating between. The film ad ded with a small amount of CuO exhibited very high sensitivity to H2S in air, being able to detect dilute H2S close to 0.02 ppm at 300 degre es C. The high sensitivity seems to result from the unique promoting e ffect of CuO coupled with the unique microstructure of the film. (C) 1 998 Elsevier Science S.A. Ail rights reserved.