Engineered carbon nanotube field emission devices

Cole, Matthew T.; Mann, M.; Teo, Kenneth B. K.; Milne, W. I.

doi:10.1016/b978-0-323-28990-0.00005-1

Cited by 19 publications

(16 citation statements)

References 294 publications

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“…Carbon nanotubes (CNTs) and carbon nanofibers (CNFs) have attracted great attention in cold field emission applications [1][2][3][4]. The ability to design CNT or CNF field emitters with predictable electron emission characteristics allow their use as electron sources in various applications such as microwave amplifiers, electron microscopy, parallel beam electron lithography and advanced X-ray sources [3,5].…”

Section: Introductionmentioning

confidence: 99%

Minimal domain size necessary to simulate the field enhancement factor numerically with specified precision

Assis

Dall’Agnol

2019

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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In the literature about field emission, finite elements and finite differences techniques are being increasingly employed to understand the local field enhancement factor (FEF) via numerical simulations. In theoretical analyses, it is usual to consider the emitter as isolated, i.e, a single tip field emitter infinitely far from any physical boundary, except the substrate. However, simulation domains must be finite and the simulation boundaries influences the electrostatic potential distribution. In either finite elements or finite differences techniques, there is a systematic error ( ) in the FEF caused by the finite size of the simulation domain. It is attempting to oversize the domain to avoid any influence from the boundaries, however, the computation might become memory and time consuming, especially in full three dimensional analyses. In this work, we provide the minimum width and height of the simulation domain necessary to evaluate the FEF with at the desired tolerance. The minimum width (A) and height (B) are given relative to the height of the emitter (h), that is, (A/h)min × (B/h)min necessary to simulate isolated emitters on a substrate. We also provide the (B/h)min to simulate arrays and the (A/h)min to simulate an emitter between an anode-cathode planar capacitor. At last, we present the formulae to obtain the minimal domain size to simulate clusters of emitters with precision tol . Our formulae account for ellipsoidal emitters and hemisphere on cylindrical posts. In the latter case, where an analytical solution is not known at present, our results are expected to produce an unprecedented numerical accuracy in the corresponding local FEF.

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Section: Introductionmentioning

confidence: 99%

Minimal domain size necessary to simulate the field enhancement factor numerically with specified precision

Assis

Dall’Agnol

2019

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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“…Large-area field electron emitters (LAFE's) typically have a "footprint area" of between 1 mm 2 and 1 cm 2 and comprise very many individual emitters. LAFEs have various potential technological applications as large-area electron sources [1][2][3] , and there has been much interest in exploring the effectiveness of different fabrication materials and procedures.…”

Section: A Backgroundmentioning

confidence: 99%

Why converting field emission voltages to macroscopic fields before making a Fowler-Nordheim plot has often led to spurious characterization results

Forbes

2019

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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ReceivedAn important parameter used to characterize large-area field electron emitters (LAFEs) is the characteristic apex field enhancement factor γ C . This parameter is normally extracted from the slope of a Fowler-Nordheim (FN) plot. Several years ago, the development of an "orthodoxy test" allowed a sample of 19 published FN plots relating to LAFEs to be tested, and it was found that about 40% of the related papers were reporting spuriously high values for γ C . In technological papers relating to LAFE characterization, common practice is to pre-convert the measured voltage into an (apparent) value of macroscopic field before making and analyzing a FN plot. This paper suggests that the cause of the "spurious-FEF-value" problem is the widespread use of a pre-conversion equation that is defective (for example, not compatible with ordinary electrical circuit theory) when it is applied to so-called "non-ideal" field emission devices/systems. Many real devices/ systems are non-ideal. The author argues that FN plots should be made using raw experimental current-voltage data, and that an orthodoxy test should be applied to the resulting FN plot before any more-detailed analysis, and that (in view of growing concerns over the reliability of published "scientific" results) reviewers should scrutinize field emission materials-characterization papers with enhanced care. a) Electronic mail: r.forbes@trinity.cantab.net

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“…Since their discovery in the early 1990’s by Ijima, the CNTs have inspired prevalent investigations amongst many researchers [ 2 ]. The outstanding electrical, mechanical and thermal properties offered by the CNTs made them to be potentially applicable in many different sectors of today’s technology including the solar cells, catalysis, engineering and biomedical [ 3 ]. However, the original CNTs surface reactive properties have the ability to easily form the self-aggregated nanostructures thus limit their application in the adsorption and dispersion sector.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Measurements of Multiwalled Carbon Nanotubes under Different Plasma Treatments

et al. 2018

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In the present work, we described the post-treatment effects of applying different plasma atmosphere conditions on the electrochemical performances of the multiwalled carbon nanotubes (MWCNTs). For the study, a composite of MWCNTs/Co/Ti was successfully grown on the silicon substrate and then pre-treated with ammonia, oxygen and hydrogen plasma. The composite was characterized by making use of field emission scanning electron microscopy (FESEM) for the surface morphology and Raman spectroscopy for the functionalization. Further, the electrochemical measurements were performed with the use of the cyclic voltammetry (CV) applied in the 0.01 M potassium ferricyanide in 0.1 M KCl solution. On testing, the results indicated that the NH3-treated MWCNTs have the highest efficiency as compared to the other pretreatments and control. This increased performance of NH3 treated sample can be linked to the enhanced surface area of the composite, thereby improved adsorption and associated interaction with that of the analyte molecules at the electrodes. Further comparison of the electrode with that of commercial Dropsens electrodes provided the confirmation for the efficiency of the NH3/MWCNTs, thereby suggesting for the potentiality of applying the NH3 modified electrode towards electrochemical applications.

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Engineered carbon nanotube field emission devices

Cited by 19 publications

References 294 publications

Minimal domain size necessary to simulate the field enhancement factor numerically with specified precision

Minimal domain size necessary to simulate the field enhancement factor numerically with specified precision

Why converting field emission voltages to macroscopic fields before making a Fowler-Nordheim plot has often led to spurious characterization results

Electrochemical Measurements of Multiwalled Carbon Nanotubes under Different Plasma Treatments

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