Gas-sensing properties of sputtered thin films of tungsten oxide

Electrical, structural and morphological properties of thin films of WO3 deposited by the reactive RF sputtering method have been analysed. The fundamental electrical features of WO3 have been determined by Hall-effect measurements. Information about the structure and morphology of these films was obtained by transmission electron microscopy techniques. The investigations of electrical properties in a controlled atmosphere at various operating temperatures revealed that WO3 is particularly suitable for NO gas detection. In particular, the relative variation of the resistance of WO3 was found to be reversible and to follow a power-law relationship. The dependence of the electrical properties on the structure and morphology has also been discussed.