Effect of electrode alterations on the a.c. behaviour of Li2OZnO humidity sensors

The dielectric behaviour of humidity sensors based on Li-doped ZnO has been investigated at frequencies from 1 Hz to 1 MHz, at room temperature. Sputtered gold electrodes and Teflon® film electrodes were used to obtain the dielectric response of the system electrodes/sensor to humidity changes. It is suggested that the main dielectric relaxation observed when Teflon electrodes are used corresponds to one of the three different dielectric relaxations observed for the system with gold electrodes. Current theories are used to discuss the origin of the observed relaxations.