Characteristics of semiconductor gas sensors I. Steady state gas response

• Published in: Sensors and actuators 1982, Vol.3, p.233-254
• Main Authors: Clifford, P.K., Tuma, D.T.
• Format: Article
• Language: English
• Subjects: carbon monoxide semiconductor sensor; chemical sensing; gas detection; oxygen adsorption; tin oxide
• ISSN: 0250-6874
• DOI: 10.1016/0250-6874(82)80026-7

The steady state gas sensing characteristics of SnO 2 gas sensors, as exemplified by the Taguchi Gas Sensor (TGS), are comprehensively studied. Resistance responses to hydrogen, methane, carbon monoxide and water vapor are experimentally characterized, with particular emphasis on multiple gas interactions. We find that the presence of ambient oxygen is essential to the sensor's operation and that the detection of combustible or reducing gas is mediated by reaction with adsorbed oxygen on the sensor surface. A quantitative model of device operation is constructed which unifies the diverse properties of the TGS and other semiconductor sensors. The model supplies the mathematical framework for meaningful comparisons of sensor performances and gas sensitivities. In addition, it provides for the intrinsic power law response of sensor electrical resistance to combustible gas concentrations, the competitive and synergistic interactions of several gases detected simultaneously, and the source of sensor unselectivity. Stoichiometries and activation energies for the pertinent oxidation reactions on the tin oxide sensor surface can be derived from a sensor's resistance response by curve fitting to the mathematical model.