Thin (<7.5 nm) Ta2O5 films were grown at atmospheric pressure on n-Si(I 0 0) wafers by chemical vapour deposition using Ta(OC2H5)(5) as precursor. X-ray photoemission spectroscopy and X-ray reflectivity were used to study the composition of the films, as-deposited and annealed at 600 and 800 degreesC in a furnace in N-2 and O-2. It appears that the thickness of the interfacial SiO2 layer depends on the temperature and not on the time of exposure to O-2. After crystallization of Ta2O5, detected at 800 degreesC by X-ray diffraction, our electrical measurements show a decrease of the leakage current. (C) 2003 Elsevier B.V. All rights reserved.