Structural study of epitaxial tungsten oxide nanoclusters

Tungsten oxide nanoclusters were prepared by evaporation of tungsten oxide powder from a specially designed evaporation cell under ultra high vacuum (UHV) conditions. The (0001), (2¯110) and (1¯102)α-Al2O3 single-crystal substrate surface orientations were used as substrates. The structure and epitaxial parameters of tungsten oxide nanoclusters were determined by reflection high-energy electron diffraction (RHEED). Structural properties of tungsten oxide deposits were found to be dependent on the substrate surface orientation and deposition conditions. Well-oriented populations of WO2 nanoclusters were observed. They exhibited preferentially (101¯) WO2 epitaxial planes.