1996 年 17 巻 7 号 p. 393-400
The chemical composition and structure of ZrO/W (100) surface were examined by means of X-ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED) in order to understand the lowering mechanism of work function on the surface. Deposition of several monolayers of zirconium onto a clean W (100) surface and following heating in oxygen ambience caused a decrease in work function and oxidation of zirconium, which was accompanied by change of the LEED, pattern. After the heating in oxygen, the crystal was flash-heated under a UHV condition at an elevated temperature. This treatment caused a chemical change from ZrO2 to Zr-O complex. The concentration of Zr-0 complex increased as the flashing temperature was raised, and at the same time, the LEED pattern changed from p (2×1) to c (4×2) pattern. The formation of Zr-O complex and the emergence of the c (4×2) pattern accompanied the lowering of work function to 2.7 eV. Stability of the Zr-O layer at a high temperature of 1800 K was also confirmed by XPS analysis at the temperature.