Structure of Pd/tungsten oxide epitaxial system

In our studies, we investigated the structure and electronic properties of Pd/tungsten oxide epitaxial system. The crystallographic structure and epitaxial orientation were determined by reflection high-energy electron diffraction. X-ray photoelectron spectroscopy was used for investigation of the chemical composition. Tungsten oxide epitaxial layers were prepared by oxidation of W(1 1 0) single-crystal surface using a radiofrequency (RF) oxygen plasma source. Two tungsten oxide phases having (1 1 1) and (0 0 1) epitaxial planes in dependence on preparation conditions were observed. The pseudocubic structure arising from a monoclinic tungsten trioxide structure by a small distortion was deduced from diffraction patterns. Deposition of a small amount of Pd led to the growth of three-dimensional Pd clusters. The (1 1 1) epitaxial and polycrystalline Pd phases were found.