Coating to Avoid Charging in SEM Samples - Practical Electron Microscopy and Database - - An Online Book - |
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Microanalysis | EM Book http://www.globalsino.com/EM/ | ||||||||
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In SEM (secondary electron microscopy) observations, especially for electrically isolated structures, charging can occur and thus SEM imaging is degorated. In such cases, the SEM specimens are often coated with a grounded metallic layer: This coating prevents from formation of positive or negative potentials at the surface and thus deflection of the incident electron beam is elliminated becasue the surface is electrically nuturalized. However, this coating layer in fact forms a kind of Faraday cage only:
[1] O. Jbara, J. Cazaux, G. Remond and C. Gilles, Halogen ion electric field assisted diffusion in fluorite and polyvinyl chloride during electron irradiation, J. Appl. Phys. 79 (5), 1, 2309 (1996).
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