Hydrogen termination and electron emission from CVD diamond surfaces: a combined secondary electron emission, photoelectron emission microscopy, photoelectron yield, and field emission study

The effect of hydrogen termination on the electron emission properties of CVD diamond surfaces is investigated. Three kinds of electron emission process, namely secondary electron emission (SEM), photoelectron emission, and held emission are compared on hydrogen free and hydrogen terminated surfaces. Electron beam stimulated desorption was employed to desorb hydrogen from the diamond surface and to pattern H-free areas on otherwise H-covered surfaces. The hydrogen terminated areas give strong electron emission in contrast to the hydrogen free surfaces for an emission processes studied. In particular, the hydrogen free patterns are imaged with comparable contrast by SEM and photoelectron emission microscopy (PEEM). This indicates that the hydrogen termination on diamond surfaces reduces the energy barrier for electron emission by lowering the electron affinity of diamond surface. This is confirmed by a drastic difference in the onset for field emission between the hydrogenated and hydrogen free parts of the same CVD diamond film. It is further demonstrated by yield spectroscopy that the threshold for electron emission below the gap of diamond is lowered by the hydrogenation process. (C) 2000 Elsevier Science S.A. All rights reserved.