Low secondary electron emission characteristics of carbon nano-onion coating via plasma enhanced chemical vapor deposition

Suppression of secondary electron emission (SEE) by surface coating technology on metal materials has important applications in many fields, for which the investigation on new coating materials with low secondary electron yield (SEY) is desired significantly. In this study, the maximum SEY of nickel (Ni) substrate was reduced from 2.30 to 0.75 (67 % reduction) after a carbon nano-onion (CNO) coating prepared by plasma enhanced chemical vapor deposition (PECVD), and the SEY less than 1 means that some problems caused by secondary electron (SE) multiplication on metal materials could be solved completely. Various measurements, material characterization and CASINO Monte Carlo model simulation indicated that the low SEY characteristic of CNO coating could be attributed to two main mechanisms: Firstly, true SEs emitted from the surface of CNO could be reabsorbed by the adjacent CNO attributed to the micrometer scale undulating structure formed by the accumulation of CNO on the coating surface; Secondly, the defects degree of CNO directly affects the emission of true SE, which plays the role of low-energy electron capturing trap. This discovery can provide a reference for future coating production.