Field electron emission characteristic of graphene

Wang, Weiliang; Qin, Xizhou; Xu, Ning; Li, Zhibing

doi:10.1063/1.3549705

Cited by 48 publications

(28 citation statements)

References 32 publications

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“…[1][2][3] Conductivity, resistance of emitter/substrate interfaces, surface work function of material and emitter tip quality are some of the important factors which determine the efficiency of field-emission. 2,4 For field emission display applications, it is necessary to grow vertically aligned carbon nanotube (CNT) arrays on a large scale with suitable emitter density and high aspect ratio.…”

Section: Introductionmentioning

confidence: 99%

High-performance field emission device utilizing vertically aligned carbon nanotubes-based pillar architectures

et al. 2018

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The vertical aligned carbon nanotubes (CNTs)-based pillar architectures were created on laminated silicon oxide/silicon (SiO2/Si) wafer substrate at 775 °C by using water-assisted chemical vapor deposition under low pressure process condition. The lamination was carried out by aluminum (Al, 10.0 nm thickness) as a barrier layer and iron (Fe, 1.5 nm thickness) as a catalyst precursor layer sequentially on a silicon wafer substrate. Scanning electron microscope (SEM) images show that synthesized CNTs are vertically aligned and uniformly distributed with a high density. The CNTs have approximately 2–30 walls with an inner diameter of 3–8 nm. Raman spectrum analysis shows G-band at 1580 cm−1 and D-band at 1340 cm−1. The G-band is higher than D-band, which indicates that CNTs are highly graphitized. The field emission analysis of the CNTs revealed high field emission current density (4mA/cm2 at 1.2V/μm), low turn-on field (0.6 V/μm) and field enhancement factor (6917) with better stability and longer lifetime. Emitter morphology resulting in improved promising field emission performances, which is a crucial factor for the fabrication of pillared shaped vertical aligned CNTs bundles as practical electron sources.

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Section: Introductionmentioning

confidence: 99%

High-performance field emission device utilizing vertically aligned carbon nanotubes-based pillar architectures

et al. 2018

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“…This leads to an effective vacuum barrier height W p = W o − E p , with W o ∼ 4.32 eV the work function of graphene, [18] for tunneling normal to the edge. [19,20] For hydrogen saturating edges, E y of the AE vanishes at the K point if l = 0 while it is 2.8eV for the ZE.…”

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confidence: 99%

“…A feasible model is V at = − P x ̺ 2 with P the dipole line density along the edge. [18] It is easy to obtain V e outside the APD region (referred to as the off-APD region) via the conformal transformation, z + i x = (z + i(x + h)) 2 + h 2 with h the height of the graphene. On the ρ = ( x, z) plane, V e = −eF 0 x.…”

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confidence: 99%

Coherent field emission image of graphene predicted with a microscopic theory

Kreuzer

2012

Phys. Rev. B

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Electrons in the mono-layer atomic sheet of graphene have a long coherence length of the order of micrometers. We will show that this coherence is transmitted into the vacuum via electric field assisted electron emission from the graphene edge. The emission current density is given analytically. The parity of the carbon pi-electrons leads to an image whose center is dark as a result of interference. A dragonfly pattern with a dark body perpendicular to the edge is predicted for the armchair edge whose emission current density is vanishing with the mixing angle of the pseudo-spin. The interference pattern may be observed up to temperatures of thousand Kelvin as evidence of coherent field emission. Moreover, this phenomenon leads to a novel coherent electron line source that can produce interference patterns of extended objects with linear sizes comparable to the length of the graphene edge. Nano-emitters of various shapes and materials have been used for cold field electron emission (CFE) with the aim of constructing a practical microelectronic vacuum electron source that may be used in flat-panel displays, electron microscopes and parallel e-beam lithography systems. The feature most important for such applications is the high aspect ratio of nano-tips enhancing the apex field to the point where field electron emission can be driven by macroscopic electric fields of about ten volts per micrometer or even less. Two successful examples of this approach are Spindt-type cathodes[1] and single atom field emission tips. [2,3] In the context of the present paper we should note that in the latter the emission volume is the terminating atom so that emitted electrons are spatially coherent as proven succinctly in in-line electron holography.[4] The coherent field emission of carbon-based nano-emitters has been confirmed with the perfect interference fringes produced by the electron beam from carbon nanotube CFE. [5,6] Several groups have demonstrated that graphene does show promising CFE properties such as a low emission threshold field and large emission current density.[7-13] What we will show in this paper is that the unique electronic properties of graphene and its monolayer atomic structure result in a novel electron line source with coherent field emission that can produce interference patterns of extended objects with linear sizes comparable to the length of the graphene edge. What makes graphene unique is that its two-dimensional electron system is well described by a superposition of 2p carbon orbitals and that its low energy excitations behave like Dirac particles. [14][15][16] Due to the perfect atomic structure, * corresponding author: stslzb@mail.sysu.edu.cn electrons in graphene have long coherent lengths (a few micrometers at room temperatures [17]). We will show that the emission electrons will carry this coherence of the quantum states of graphene into the vacuum.The challenge is to explain/predict the coherent aspect of the CFE image. Because of its wave nature coherent emission electrons must have been ...

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“…Moreover, graphene has an ambipolar field-effect and quantum Hall ferromagnetic characteristics. [2][3][4][5] Benefiting from the above superior properties, graphene has been highly attractive both in industrial and fundamental research. For example, in lithium-ion batteries, many metal oxide anode materials have used graphene sheets as an ideal matrix material.…”

Section: Introductionmentioning

confidence: 99%

Research Progress of Preparation Methods of Graphene Nanocomposites for Low-Temperature Fuel Cells and Lithium-Ion Batteries

Wang¹,

Zhou²,

Zhu³

et al. 2016

Kem. Ind.

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Because of its unique two-dimensional structure, huge specific surface area, high electrical conductivity, and other excellent performances, graphene has shown great potential for application in catalysis, electronics, sensors, energy storage, and other areas. Especially, graphene nanocomposites have been found to be promising catalyst support for low-temperature fuel cells, and as anode nanomaterials for high reversible capacity and excellent rate capability for lithium-ion batteries, which has triggered a new round of research hotspot. Preparation methods of graphene nanocomposites mainly for low-temperature fuel cells are reviewed. Particularly, the research progress and principles of physical preparation methods (molecular beam epitaxy), chemical preparation methods (chemical reduction, electrochemical deposition and hydrothermal/solvothermal methods, etc.) and high-energy ball milling are summarized. Research outlook of graphene nanocomposites for low-temperature fuel cells are prospected.

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Field electron emission characteristic of graphene

Cited by 48 publications

References 32 publications

High-performance field emission device utilizing vertically aligned carbon nanotubes-based pillar architectures

High-performance field emission device utilizing vertically aligned carbon nanotubes-based pillar architectures

Coherent field emission image of graphene predicted with a microscopic theory

Research Progress of Preparation Methods of Graphene Nanocomposites for Low-Temperature Fuel Cells and Lithium-Ion Batteries

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