A Physics-Based Noise Model for Metallic Oxide Gas Sensors Characterization

In this contribution, we show new results of low frequencies noise characterization of metal oxide gas microsensors with WO3 sensitive thin film. The spectral form of the measured noise responses using our specific systems is similar for tested gases (ozone and nitrogen dioxide). We observe a clear lorentzian behavior according to adsorption-desorption noise theory. To identify the detected gas, a physical-based characterization model of adsorption-desorption noise source is proposed and compared with the empirical flicker noise model. We show that the excess noise is due to the adsorption-desorption processes on the surface of the sensors sensitive film. The lorentzian parameters depend on the nature of gas and the noise level dependence with gas concentration is clearly demonstrated. This confirms the interest of noise spectroscopy to improve the selectivity of gas sensors.