On the origin of the humidity-sensitive electrical properties of porous aluminium oxide (sensor application)

Porous Al2O3 films exhibit interesting humidity-sensitive electrical properties. The authors have found that the conventional electrical equivalent circuit approach to interpret the properties of an Al2O3 humidity sensor is inadequate. This paper discusses the shortcomings of the model and proposes a theory based on physical adsorption phenomena, surface conduction mechanisms and the dielectric properties of the Al2O3 film. It is shown that the capacitance and resistance characteristics of the sensor derived by the theory agree with the experimental characteristics both in the nature of the variation and the frequency dependence.

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