Atomic arrangement on ZrO/W(100) cathode surface - Models for LEED intensity vs. voltage analysis

The ZrO/W(100) thermal field emitter has been widely used for cathodes in electron microscopy because this surface shows a remarkably low work function. In spite of its wide application, the reducing mechanism of the work function has not been clearly understood. On the ZrO/W(100) surface, Zr is considered to be located at an outermost position and O is just below it because the Zr-O pair has an electric dipole whose positive side is Zr, and it makes an electric double layer, which is reasonable for work function reducing. For confirmation of the atomic arrangement, low-energy electron diffraction (LEED) intensity vs. voltage (I-V) analysis was done. At stage 1 of LEED I-V analysis, the most simple models were built and calculated. The result showed poor possibility of these models. Several mon complex models, which should be considered, are shown in this study. (C) 1999 Elsevier Science B.V. All rights reserved.