Surface reconstruction of a field electron emitter |
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Authors: | K A Nikiforov N V Egorov Che-Chou Shen |
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Institution: | 1. St. Petersburg State University, St. Petersburg, Russia 2. National Taiwan University of Science and Technology, Taipei, Taiwan
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Abstract: | The surface and emission images of a metal field’s electron cathode in the form of a tip are simulated. The surface structure
is calculated in the thin-shell and broken-bond (local-environment) models for the perfect crystal lattice. The cathode shape
and macroscopic electric field are represented by the sphere-on-cone model. The amplification of a local electric field is
the adjustable parameter of the model. The method of determination of the emitter tip’s crystal faces based on the analysis
of the surface atoms’ environment geometry is proposed. It is shown that it is enough to restrict the consideration of geometric
environment by the fifth order of the nearest neighbors for the emitter radius of 100–1000 lattice parameters (31.6–316 nm
for the tungsten). The crystallographic model of work function anisotropy in the broken-bond approach is used: the local work
function’s value is set in accordance with Miller indices of the face containing this area. The model adequacy is corroborated
by the comparison of current-voltage characteristics and emission images with the data of the natural experiment. |
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