Effect of Annealing Temperature on the Sheet Resistance and Secondary Electron Emission Yield of Chromium Oxide-Coated Alumina

Abstract

A flashover along the surface of a solid insulator in vacuum is a discharge phenomenon that can result in device damage, and this issue limits, for example, the applicable maximum voltage of charged-particle accelerators. One effective approach to improve the withstand voltage of the insulator is to coat it with a slightly electrically conductive film. In this study, we evaluated the impact of the annealing temperature on the sheet resistance and the secondary electron emission yield (SEEY) of alumina substrates coated with an about 10-nm-thick chromium oxide film. To identify the origin of the observed trend in the SEEY data, we evaluated the oxidation state of the chromium atoms in the film by X-ray photoelectron spectroscopy (XPS), and we also measured the surface morphologies of chromium coatings on silicon prepared in the same way. The results indicate that the SEEY strongly depends on the grain size and the residual metallic chromium content.