Adsorption and Desorption of Gas Molecules on SnO2 Material for Temperature-Modulation of Mos Sensors

Gas sensors with MOS for the detection of toxic explosive gases have been intensely investigated due to their ease of operation, low cost and nice sensitivity. As the materials of MOS, SnO 2 has gained particular attention owing to its outstanding sensitivity, high conductivity and chemical stability, but the poor selectivity is still a worst disadvantage for use of SnO 2 -based gas sensors. In this work, we try to improve the selectivity via temperature-modulation that the sensing cell and the heating cells are integrated to be a sensor, gas molecules is distinguished at different temperature according to dynamic difference of gas molecules adsorption on sensing materials. As a base, effect of adsorption and desorption of CO and H 2 on the response is investigated during the process of temperature change. The result was as shown in Fig.1 that adsorption and desorption of H 2 molecules on SnO 2 materials had been a dynamic equilibrium in temperature range from 300 o C, 350 o C to 400 o C, in which at 350 o C H 2 molecules were adsorbed most more on thermodynamics, and the rate of adsorption and desorption of H 2 molecules was controlled by diffusion of gas molecules on dynamics. This provides an experimental base to improve the sensing characteristics of SnO 2 materials. Figure 1