Structure engineering of WO3 nanoparticles for porous film applications by advanced reactive gas deposition

Abstract Fine-grained crystalline or amorphous thin films are normally produced by atomistic deposition of species under conditions giving a low adaton mobility. Here we consider an alternative high-temperature route employing advanced reactive gas deposition for structure engineering of WO 3 nanoparticles in making nanocrystalline films, especially, for gas sensing applications. For instance, structure engineering may be necessary in the case of very fine-grained n-type semiconductor oxide films in order to increase the electrical conductivity of the films. The crystal structure of WO 3 together with its different phases makes possible structure engineering of its nanoparticles by high-temperature processes such as the reactive gas deposition. Produced nanocrystalline WO 3 films in metastable tetragonal crystal structure were found to be very sensitive to H 2 S in air already at room temperature.