CO and CO2 thin-film SnO2 gas sensors on Si-substrates

Thin-film SnO2 gas sensors have been structured on Si substrates. The sensors are temperature stable at 900 deg C in synthetic air for 48 h. No significant outdiffusion of the sensor layers can be observed after annealing. Pt catalysts lead to CO sensors without cross sensitivity to CO(2-) Pt/Ca catalyst combinations also lead to CO2 gas response. CO2 sensitivity between 1000 and 10000 ppm has been demonstrated at 270 deg C. CO2 might be indirectly detected via humidity exchange between CO2 and the heated Ca-catalysed SnO2 surface.