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Photoemission spectroscopy and electron diffraction study of Pd/tungsten oxide/W(110) epitaxial system

2008; IOP Publishing; Volume: 100; Issue: 1 Linguagem: Inglês

10.1088/1742-6596/100/1/012008

1742-6596

K. Mašek, Slavomír Nemšák, M Mravcáková, P. Blumentrit, Tomáš Škála, M. Škoda, Vladimı́r Matolín,

ZnO doping and properties

Epitaxial thin films of tungsten oxide were prepared by radio-frequency plasma oxidation of the W(110) surface followed by thermal annealing. Reflection High-Energy Electron Diffraction (RHEED) showed that the films were composed of crystal grains having a pseudo-cubic structure and (111) epitaxial plane. The re-crystallisation process led to the reduction of the tungsten oxide films. A lack of oxygen atoms was compensated by a formation of crystallographic shear planes (CSP). Deposited Pd atoms formed three-dimensional clusters with a (111) epitaxial plane reflecting the hexagonal symmetry of the tungsten oxide surface lattice. Electronic structure of the Pd/tungsten oxide/W(110) was investigated by means of X-ray Photoelectron Spectroscopy (XPS) and Synchrotron Radiation Photoelectron Spectroscopy (SRPES) methods. The epitaxial tungsten oxide thin film exhibited well-defined oxidation states indicated by narrow components in the W 4f spectrum which were not observed in amorphous phase. The deposition of Pd led to significant changes in the valence band structure but the detailed analysis of W 4f and Pd 3d lines did not show a direct interaction of Pd and W species.