Zro/W(100)表面のX線光電子分光と低速電子線回折による同時観察

概要

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The W (100) surface with several monolayers of Zr and a trace of oxygen, i.e. ZrO/W (100), is known to have a very low work function, and has been applied to thermal field cathodes. In situ observation by means of X-ray photoelectron spectroscopy and low energy electron diffraction are performed with the aim of understanding why the work function is so low. Several monolayers of Zr were deposited on a W (100) single crystal surface. Heating in an oxygen pressure of the order of 10-5 Pa induces a rise of the work function by 0.8 eV. After evacuating the oxygen, heat treatment was performed under an ultrahigh vacuum condition at 2100 K, upon which the work function dramatically decreased by 1.9 eV from that of the clean W (100) surface. This phenomenon was accompanied by clear changes of the LEED pattern and the XPS spectra. The LEED pattern changed from (2×1) to a more complicated pattern. The XPS peak of the Zr-3d spectra shifts to an intermediate position between those of the pure Zr and ZrO2, suggesting that a Zr-O composite is formed at the surface.
日本真空協会の論文
1995-05-20