Carbon nanotubes as electron sources

Milne, W. I.; Teo, Kenneth B. K.; Mann, M.; Bu, Ian Y.Y.; Amaratunga, G.A.J.; Jonge, Niels de; Allioux, Myriam; Oostveen, Jim T.; Legagneux, Pierre; Minoux, E.; Gangloff, L.; Hudanski, L.; Schnell, J. P.; Dieumegard, L. D.; Peauger, F.; Wells, Torquil; El-Gomati, Mohamed

doi:10.1002/pssa.200566101

Cited by 38 publications

(20 citation statements)

References 11 publications

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“…This artifact, however, does not limit the experimental detail reported here as our purpose is to investigate the spatially variation trend in β with CN pitch. <β array > for the 1, 2, 6, 8 and 10 µm pitch arrays were 95, 143, 196, 261 and 278 respectively, clearly demonstrating that the more closely packed CNs exhibit a reduction in β array due to enhanced nearest neighbor electrostatic shielding, as originally predicted by112021. As the CNs become increasingly close-packed adjacent CNs begin to reduce the penetration depth of the equi-potentials.…”

Section: Resultsmentioning

confidence: 55%

Deterministic Cold Cathode Electron Emission from Carbon Nanofibre Arrays

Cole

Teo

Gröening

et al. 2014

Sci Rep

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The ability to accurately design carbon nanofibre (CN) field emitters with predictable electron emission characteristics will enable their use as electron sources in various applications such as microwave amplifiers, electron microscopy, parallel beam electron lithography and advanced Xray sources. Here, highly uniform CN arrays of controlled diameter, pitch and length were fabricated using plasma enhanced chemical vapour deposition and their individual emission characteristics and field enhancement factors were probed using scanning anode field emission mapping. For a pitch of 10 mm and a CN length of 5 mm, the directly measured enhancement factors of individual CNs was 242, which was in excellent agreement with conventional geometry estimates (240). We show here direct empirical evidence that in regular arrays of vertically aligned CNs the overall enhancement factor is reduced when the pitch between emitters is less than half the emitter height, in accordance to our electrostatic simulations. Individual emitters showed narrow Gaussian-like field enhancement distributions, in excellent agreement with electric field simulations.C arbon nanotubes and nanofibres (CNs); highly-conductive high-aspect ratio graphitic carbon allotropes, have attracted immense interest for field emission applications over the past decade [1][2][3][4][5] . Their resilience towards electromigration and their ability to carry higher current densities than conventional materials coupled with their rapid response time and low driving voltages make them ideal candidates for various electron emission applications, such as micro X-ray sources 6,7 , microwave amplifiers 8 , travelling wave tubes 9 , ultra-high resolution electron microscopy 6 , and highly-parallel electron beam lithography micro-gun systems 10,11 . Conventional refractory metal emitters, such as chemically etched W tips, or Spindt-like emitters often have poorly defined tips with low aspect ratios and poor tip-to-tip reproducibility, making it difficult to predict their emission characteristics accurately, whilst cold cathode electron emitters with engineered field enhancement factors and deterministic electron emission characteristics have been hitherto unmanufacturable en masse due to difficulties in achieving high process uniformity during fabrication. Extremely uniform arrays of CNs 12 offer many advantages. Such vertically aligned CNs have near-ideal whisker-like shapes with hemispherical tips, where the tip radius is controlled by the metal catalyst which nucleates the CN growth. Moreover, the position and pitch of the CN are determined by simple matured lithographic techniques.Here we present direct scanning anode field emission mapping measurements detailing the field enhancement factor distribution from highly uniform arrays of CNs of varying pitch through which we assess the accuracy of simple geometric arguments in determining the field enhancement factor of individual CNs and arrays of CNs. Individual CNs show field enhancement factors that are in excellent agreemen...

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Section: Resultsmentioning

confidence: 55%

Deterministic Cold Cathode Electron Emission from Carbon Nanofibre Arrays

Cole

Teo

Gröening

et al. 2014

Sci Rep

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“…1͑f͔͒, synthesized by plasma enhanced chemical vapor deposition ͑PECVD͒, 5 are highly compatible with microfabrication, thereby facilitating their incorporation as functional nanostructured components of a large variety of devices. Demonstrated CNF applications include electron field emitters, [16][17][18][19] charge and hydrogen storage media, 20,21 composite materials, 22,23 biosensors, 8,9,24,25 gene delivery arrays, [26][27][28][29] synthetic membrane structures, 30,31 electrochemical probes, 13,32,33 electrodes for neuronal interface, 34,35 and scanning probe microscopy ͑SPM͒ tips. [36][37][38] The structure and surface chemistry of the nanofibers play a crucial role in the performance characteristics of these nanofiber-based devices.…”

Section: Introductionmentioning

confidence: 99%

Surface characterization and functionalization of carbon nanofibers

Klein¹,

Melechko²,

McKnight³

et al. 2008

Journal of Applied Physics

166

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Carbon nanofibers are high-aspect ratio graphitic materials that have been investigated for numerous applications due to their unique physical properties such as high strength, low density, metallic conductivity, tunable morphology, chemical and environmental stabilities, as well as compatibility with organochemical modification. Surface studies are extremely important for nanomaterials because not only is the surface structurally and chemically quite different from the bulk, but its properties tend to dominate at the nanoscale due to the drastically increased surface-to-volume ratio. This review surveys recent developments in surface analysis techniques used to characterize the surface structure and chemistry of carbon nanofibers and related carbon materials. These techniques include scanning probe microscopy, infrared and electron spectroscopies, electron microscopy, ion spectrometry, temperature-programed desorption, and atom probe analysis. In addition, this article evaluates the methods used to modify the surface of carbon nanofibers in order to enhance their functionality to perform across an exceedingly diverse application space.

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“…The focussed spot diameter (d T ) is therefore composed of a number of contributing sources where their diameters can be simply expressed as the original source of emitted electrons (d o ), the chromatic . All of these sources are from the author's research group at the University of York [11][12][13] aberration (d C ), spherical aberration (d S ) and diffraction effects (d D ). These contributions could be added in the following manner:…”

Section: The Probe-forming Column (Electron Lenses)mentioning

confidence: 99%

Modern Electron Optics and the Search for More Light: The Legacy of the Muslim Golden Age

El-Gomati

2016

Optics in Our Time

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Carbon nanotubes as electron sources

Cited by 38 publications

References 11 publications

Deterministic Cold Cathode Electron Emission from Carbon Nanofibre Arrays

Deterministic Cold Cathode Electron Emission from Carbon Nanofibre Arrays

Surface characterization and functionalization of carbon nanofibers

Modern Electron Optics and the Search for More Light: The Legacy of the Muslim Golden Age

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