Gas reception and signal transduction of neat tin oxide semiconductor sensor for response to oxygen

The basic schemes of gas reception and signal transduction recently proposed for oxide semiconductor gas sensors have been shown to apply well to the quantitative analysis of the oxygen response behavior observed with a neat SnO2 sensor under various humidity conditions at 623 K. It was shown that O2- ions are preferably formed under a very dry condition but their formation is strongly suppressed in the presence of slight amounts of moisture through blocking of adsorption sites and induction of threshold pressure, and is replaced by the formation of O- ions. To make the situation more complex, the formation of these ions was increasingly enhanced with increasing humidity of pretreatment ambient at elevated temperature (hysteresis), which is considered to result from surface restructuring having taken place in the pretreatments. Through these results, chemical properties and stabilities of grain surface, beside physical properties of the grains, were shown to be critically important for gas sensing properties. (C) 2013 Elsevier B.V. All rights reserved.