Ultralow Secondary Electron Emission of Graphene

Abstract

In order to ensure that vacuum electronic devices work with high overall efficiency, it is required to use materials with low secondary electron emission to fabricate or coat collectors, grids, and envelope walls of the devices. We report that the secondary electron yields of monolayer graphenes are ultralow, comparable with the lowest yields of the materials currently used in this practical application. This offers a pathway for the application of light graphene with only one-atom thickness and good electronic and thermal conductivities in vacuum electronic devices.

Calculations of secondary electron yield of graphene coated copper for vacuum electronic applications

“…Furthermore, we denote the graphene workfunction as W G (d), with d being the graphene thickness. For a thin layer of graphene, typically around 5 Å as noted by Luo et al, 22 the value of W G (d) would be close to the workfunction of copper (W Cu ). In any case, from energy considerations, one gets the condition: where ∆V is the interfacial potential step due to charge transfers between copper and graphene, and …”

“…21 Even more dramatic improvements in SEY values to about 0.1 were obtained by depositing a few monolayers of graphene on the electrode. 22 However, these experiments were conducted at a fixed incident electron energy of 1 keV, and the energy-dependent behavior was not probed. 23 The advantage of using graphene is that neither any post-treatment, nor ion-sputtering, is required for such an approach.…”

“…Thus it remains unclear why the modest shifts might cause large changes in SEY values from over 1.0 for pure copper, as reported. 22,[26][27][28] Here we focus on the two-dimensional nature of the graphene layers. Transmission of secondary electrons incident on the metal-graphene interface from the metal would conserve momentum along the parallel direction during their transit.…”

Defect-induced discriminative modulation of the highest occupied molecular orbital energies of graphene

“…Graphene's fascinating properties, which include exceptionally high charge carrier mobility, 1-3 transparency, 4 thermal conductivity, 5,6 mechanical strength, 7 chemical properties 8 and ultralow secondary electron emission, 9 have led to its intense investigation. Modulating such properties has been a focus of research towards the development of graphene-based devices.…”

Response to “Comment on ‘Secondary electron yield of multiwalled carbon nanotubes’” [Appl. Phys. Lett. 99, 126103 (2011)]

“…In addition, Luo et al recently published another paper, reporting "ultralow" SE yield from graphene. 10 While it is not surprising that SE yield from graphene should be low, Luo et al contrast this ultralow yield with their claimed "ultrahigh" yield from nanotubes, and attribute it to the difference in the two structures. We disagree with this argument and reiterate that we believe the experiments/explanations presented by Luo et al in Ref.…”