Abstract
Deep investigations were performed for further understanding of the nanostructure of sputtered WO3 films. The as-deposited films consisted of fine crystallites of several nm. As the pressure increased, the film density decreased and the surface area increased owing to open pores between grains. When films were annealed at 400°C or above, they were well crystallized to form monoclinic and randomly-shaped grains. Upon this crystallization, the film shrank and its density increased slightly, while the relative surface area substantially decreased.
