Ultrathin VOx/TiO2(110) (x ≈ 1)film preparation by controlled oxidation of metal deposits

Metallic vanadium ultrathin films deposited on the TiO2 (110) surface are easily oxidised to VO2 when they react with O-2 in the high vacuum pressure range. We have found that the oxidation can be stopped at VOx (x approximate to 1)when annealing of the metal film is carried out in UHV, by exploiting the reaction with bulk-to-surface diffusing oxygen. By adopting carefully optimised experimental conditions (e.g. metal film thickness and annealing temperature), locally ordered VOx films with a thickness of up to 5 ML can be prepared. X-ray photoelectron spectroscopy and angle-scanned photoelectron diffraction, as an in situ structural characterisation tool, have proven to be extremely useful in order to find optimised conditions for the whole process. (C) 1999 Elsevier Science B.V. All rights reserved.