Narrow energy distributions of electrons emitted from clean graphene edges

Abstract

This paper presents a study on electron field emission (FE) into ultrahigh vacuum (UHV) from a single, cleaned, graphene sheet where its single sheet nature has been carefully characterized and the emission zones are unambiguously the sheet edges. This definitive approach is in contrast to almost all other studies in the literature and can now guide theoretical work and applications. Our sample characterization starts with transmission electron microcopy imaging, Raman characterization, controlled mounting of individual flakes in a scanning electron microscope followed by in situ high temperature and high field treatments. Detailed FE characterization was carried out including current-voltage plots, FE microscopy, and electron energy spectroscopy during subsequent stages of sample cleaning, at room and liquid air temperatures. The full width at half maximum (FWHM) of the energy peak as well as its relative shift versus current and voltage were explored. A notable result is that the energy spectra are very narrow, ten times less than previously reported.

A quantum mechanical model of electron field emission from two dimensional materials. Application to graphene

“…The characteristics of the emitting surface can nowadays be well controlled and correlated to emission properties (for a recent example, see ref. 4). However, in some experiments, significant current levels were extracted from the central flat part of individual single-and few-layer graphene flakes.…”

Micro-engineered Nanowire Electron Source for Atomic Resolution Imaging

“…Electron source-relevant nanostructures, to name a few, include: 0D atom clusters, 1D nanotube/nanowires (NW/NT), 2D nanosheets, high work function noble metal pyramids and negative electron a nity lms. (2,(10)(11)(12)(13)(14)(15) However, only few such nanostructured electron sources succeeded in producing SEM images of nanometer resolution and none has proven capable of atomic resolution imaging in TEM. (1,(16)(17)(18) Angular alignment is one of the most important procedure to achieve high resolution imaging in electron microscopy.…”

Coulomb blockade and quantum confinement in field electron emission from heterostructured nanotips

“…Several experimental observations of FE from individual nanostructures [4][5][6] and molecules [7] in the single-electron regime have been reported over the last decade. The most remarkable behavior (in comparison to solid-state devices) was observed for nanostructures attached to a needle-shaped cathode and located at a macroscopic distance from the anode.…”

“…The most remarkable behavior (in comparison to solid-state devices) was observed for nanostructures attached to a needle-shaped cathode and located at a macroscopic distance from the anode. In particular, the Coulomb staircase was observed for temperatures of up to 1000 K, operating currents up to several microamperes, and voltages, necessary to transfer an extra electron to the nanostructure, of few hundreds of volts [4,6]. In these pioneering experiments single-electron charging was observed for carbon nanotubes and nanowires where quantum confinement effects are small and are not manifested in FE.…”

“…Selforganization of such kind of nanostructures is a well-known phenomenon in FE from uncleaned emitters, e.g. carbon nanotubes [8,9], graphene [10], tungsten tips [11,12] and Spindt cathodes [13]. In this case, electrons tunnel into the vacuum through discrete energy states (separated by a characteristic energy, Δε, see Fig.…”