The growth of wafer-scale and uniform monoclinic VO2 film was a challenge if considering the multivalent vanadium atom and the various phase structures of VO2 compound. Directly oxidizing metallic vanadium film in oxygen gas seemed to be an easy way, while the oxidation parameters were extremely sensitive due to the critical preparation window. Here we proposed a facile thermal oxidation by water-vapor to produce wafer-scale VO2 films with high quality. Results indicated that by using the water-vapor oxidant, the temperature window for VO2 growth was greatly broadened. In addition, the obtained wafer-size VO2 film showed very uniform surface and sharp resistance change. The chemical reaction routes with water-vapor were calculated, which favored the VO2 film growth. Our results not only demonstrated that the water-vapor could be used as a modest oxidizing agent, but also showed the unique advantage for large size VO2 film preparation.
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