Silicon Planar Humidity Sensor Using Anodic Oxidized Aluminum

Abstract

A planar humidity sensor using anodic oxidized aluminium film (Porous alumina) has been developed. The basic structure of sensor is similar to n-MOSFET except that the gate region is formed by porous alumina as a humidity sensing element. Anodic oxidation is carried out in dilute H₃PO₄ solution at constant voltage of 10V. The sensors show a large current response for exposure to a high humidity (>50% RH) at room temperature. The time response of sensor during transient exposure to humidity is a few minutes. The mechanism of the current response to humidity is qualitatively discussed.