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RESEARCH PRODUCT

MoO (x≤2) ultrathin film growth from reactions between metallic molybdenum and TiO2 surfaces

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Abstract Exposures to oxygen at room temperature and annealings under vacuum were carried out on deposits obtained from molybdenum interacting with (1 1 0) TiO 2 surfaces in order to obtain molybdenum oxide ultra thin films. Exposures to oxygen at room temperature show that the interfacial molybdenum oxide layers resulting from the TiO 2 /Mo interactions are inactive towards oxygen whereas the metallic molybdenum clusters, which grew on top of the interfacial layers, oxidise into MoO 3 . Besides, during annealings under vacuum, substrate oxygen anions can diffuse into the deposit. Thus, between 400 and 500°C, molybdenum oxide layers are progressively oxidised into MoO 2 . Moreover, from the annealing temperature, it is possible to control the film oxidation and to select its stoichiometry. At higher temperatures, MoO 2 layers oxidise, leading to MoO 3 clusters which sublimate restoring a clean TiO 2 surface. As concerns the metallic clusters, if they are exposed to air and then oxidised in MoO 3 prior to annealing, they sublimate below 300°C.