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

Abstract

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.