Gold promoted Li–Fe2O3 thin films for humidity sensors

A study of iron oxide thin films doped with Li and Au for humidity sensing applications is reported. The characteristics of sensitivity, linearity and stability of humidity sensors based on these films were investigated and correlated to the structural and textural properties of the sensing layer. Such properties are influenced by the nature of the dopant and the thermal treatment. Li creates preferential adsorption sites for the H2O molecules thus increasing the sensitivity at low RH. Gold instead reduces the drift of the resistance baseline stabilizing the presence of amorphous iron oxide phases. By optimizing the thermal treatment of Au-doped Li–Fe2O3 thin films, humidity sensors with high sensitivity, linearity and good stability have been developed.