CO AND CO2 THIN-FILM SNO2 GAS SENSORS ON SI SUBSTRATES

Thin-fim SnO2 gas sensors have been structured on Si substrates. The s ensors are temperature stable at 900-degrees-C in synthetic air for 48 h. No significant outdiffusion of the sensor layers can be observed a fter annealing. Pt catalysts lead to CO sensors without cross sensitiv ity to CO2. Pt/Ca catalyst combinations also lead to CO2 gas response. CO2 sensitivity between 1000 and 10 000 ppm has been demonstrated at 270-degrees-C. CO2 might be indirectly detected via humidity exchange between CO2 and the heated Ca-catalysed SnO2 surface.