Stable Secondary Electron Emission from Chemical Vapor Deposited Diamond Films Coated with Alkali-Halides

摘要

Stable secondary electron emission from cesium terminated Chemical Vapor Deposited (CVD) diamond films has been observed. Total secondary yield coefficients (sigma) ranged from 25 to 50 and were stable under continuous exposure to an electron beam from targets tested for up to 170 h. Primary current densities ranged from 1.5 to 50.0 mA/sq cm. Targets were coated with CsI from 10 to 100 nm thick. Auger electron spectroscopy was used to show that the emission was activated by electron beam induced iodine depletion after short beam exposures, leaving a Cs terminated diamond surface independent of the initial CsI thickness. The electron beam activated-alkali terminated surface is air stable and stable during heating in vacuum up to 120 C. This behavior has also been observed from CVD diamond coated with CsF, KCl, and NaCl.