MODELING AND SIMULATION OF TIN OXIDE-BASED THICK-FILM GAS SENSORS USING MONTE-CARLO TECHNIQUES

An advanced model has been developed to explain the experimental resul ts obtained from tin oxide sensors in the presence of carbon monoxide and/or water vapor. The basic principles of the proposed model applied to the simulation are that (a) there is a reduction of the tin oxide surface by both CO and water vapor, (b) at low temperatures, the oxyge n vacancies cannot be refilled, (c) in the presence of both CO and wat er vapor, formate species are formed which, when they desorb, increase the sensor's resistance, and (d) hydroxyl species increase the electr on-availability and thus the sensitivity in CO. Simulation results are in excellent qualitative agreement with the experimental ones.