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

For gas sensor applications, thin-films (thickness ∼1 μm) of SnO2(Pd, Pt) have been synthesised on oxidized silicon 〈100〉 in the temperature range of 460–560°C using pyrolysis of an aerosol. By doping with Pd or Pt metallic particles (1–12 wt.%) selectivity and sensitivity were improved. Electrical measurements under 300 ppm of CO were performed on thin films in steady-state and dynamic modes. Sensitivity, rate and response time were studied. The optimum synthesis conditions were determined in order to obtain the best microstructure of the films and the best concentration of 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 mechanisms were discussed.