Influence of Pd and Pt additives on the microstructural and electrical properties of SnO2-based sensors

For gas sensor applications, thin-films (thickness similar to 1 mu m) of Sn O2(Pd, Pt) have been synthesised on oxidized silicon [100] in the temperatu re range of 460-560 degrees C using pyrolysis of an aerosol. By doping with Pd or Pt metallic particles (1-12 wt.%) selectivity and sensitivity were i mproved. Electrical measurements under 300 ppm of CO were performed on thin films in steady-state and dynamic modes. Sensitivity, rate and response ti me were studied. The optimum synthesis conditions were determined in order to obtain the best microstructure of the films and the best concentration o f doping additives for the detection of the carbon monoxide in the range of room temperatures. The mechanism of the sensor response to CO and the role of the additives (Pd, Pt) on the basis of chemical and electronic mechanis ms were discussed. (C) 1998 Elsevier Science S.A. All rights reserved.