Shearing-Type Electron Emission

Abstract

“Stretching” and “shearing” are two basic types of depriving neutral matter from a solid. In principle, depriving charged matter from a solid also have similar counterparts. By now, most investigations on electron emission, which is a typical example of depriving charged matter, from a solid are focused on the “stretching” type while another type is rarely considered. The purpose of this work is to explore the possibility and feasibility of another type of depriving charged matter from a solid. Based on quantum many-body theory, this work reveals a feasible technique route of “shearing” electrons from the surface of a metal. Exchange potential among surface electrons can significantly modify dispersion relation curve of the surface 2D band and hence its electronic structure. Flatten dispersion relation curve near the highest occupied state enables a small scalar potential perturbation (at eV-level) to induce a large increment in parallel-to-surface momentum \(\hbar {{k}_{{||}}}\) as well as that in kinetic energy (KE) (at tens eV-level). Such a high KE is sufficiently to warrant emitted electrons to surpass, rather than tunnel, barrier in vacuum. This can be achieved even for external DC fields at very low strengthes such as 1 V/mm level and 10^–4 Tesla-level. Independence of high-voltage component/element implies a broad application prospect of this phenomenon, especially as an electron source. Targeted designing electrodes enables such a route to yield a practical electron emission source.