Electrical characterization of Fe2O3 humidity sensors doped with Li+, Zn2+ and Au3+ ions

Li-, Zn- and Au-doped Fe2O3 thin films have been investigated as humidity sensing materials. Their electrical properties have been studied in the 0-100% relative humidity (RH) range by means of electrochemical impedance spectroscopy (EIS). This has allowed to drawn an equivalent circuit which well fit experimental data obtained from the doped films. The resistive and capacitive elements of the equivalent circuit have been also calculated by a modeling procedure. Results indicate that the humidity characteristics of the doped sensing films are correlated to the charge density and surface concentration of the dopants.