Microstructure Investigation in Thin Films WO3 Produced by Pulsed Laser Deposition

The WO3 films were grown by pulsed laser deposition (PLD) on Si [100] substrate, using an Nd-YAG laser (lambda = 355 mm, LOTIS TII). The substrate was heated from 25 degrees C up to 650 degrees C and the films were deposited in oxygen pressures 5 Pa. To characterize the structure and morphology of the surface we used the XPS, TEM and HREM. From XPS analyses, it was clearly established, that even though in PLD process was used oxygen atmosphere in thin films we observed two phases WO3 and small amount WO2. The amorphous structure of thin films with small crystallites obtained at ambiance temperature was observed. At temperature T = 650 degrees C TEM analysis show crystalline structure with crystallites about 5 divided by 10 nm in diameter.