2009 Volume 7 Pages 319-322
X-ray Photoelectron Spectroscopy was conducted on magnetron sputtered WO3 thin films, following a sequence of ultra high vacuum anneals from 100°C to 900°C. Annealing from 100°C to 400°C induced an upward surface band bending of about 0.3 eV, attributed to the oxygen migration from the bulk to the surface, but no changes in the surface topography. Chemical changes occurred from 600°C to 800°C, associated to the formation of secondary oxide species. Ag deposition did not induce any band bending, indicating that the Fermi level is pinned. The Ag was entirely removed from the surface after annealing at 600°C. The implications in terms of gas sensing are discussed. [DOI: 10.1380/ejssnt.2009.319]