Physical origin of non-linearity in Fowler–Nordheim plots of aligned large area multi-walled nitrogen-containing carbon nanotubes

Chen, Y; Deng, S.Z.; Xu, Ning; Chen, J; Ma, Xucun; Wang, E.G

doi:10.1016/s0921-5093(01)01871-8

Cited by 43 publications

(19 citation statements)

References 13 publications

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“…However, it is based on the free-electron model and has proven only truly valid for electron-dense metallic emitters515. CN ensembles have been shown previously to deviate from this model, particularly in the high field regime161718. For the arrays considered here the total emission current density, J, is derived by spatially integrating the emission current over entire array, such that;…”

Section: Resultsmentioning

confidence: 99%

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: 99%

Deterministic Cold Cathode Electron Emission from Carbon Nanofibre Arrays

Cole

Teo

Gröening

et al. 2014

Sci Rep

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“…This is quite common and can be ascribed to the space charge effect. 34 If we know the work function of the emitter, the field enhancement factor (b) could be derived from the slope of the F-N plot.…”

Section: Resultsmentioning

confidence: 99%

Improvement of field emission properties of α-Fe2O3 nanoflakes due to the lowered back contact barrier after high energy X-ray irradiation

Wang

et al. 2013

Journal of Applied Physics

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Improvement in the field emission properties of α-Fe2O3 nanoflakes is observed after high energy X-ray irradiation from synchrotron radiation. Field emission threshold field of α-Fe2O3 nanoflakes is found to decrease from 10.1 to 7.8 MV/m after X-ray irradiation with the dose of 9.0 × 1014 phs/cm2. Electrical measurement reveals that the potential barrier at the back contact between the α-Fe2O3 layer and the iron substrate changes after X-ray irradiation. The observed threshold field decrease is well explained by the changes in potential barrier at the back contact of α-Fe2O3 nanoflakes, which indicates the back contact plays an important role in controlling the field emission properties of α-Fe2O3 nanoflakes. Our study shows that the α-Fe2O3 nanoflakes are a promising material for the application as field emitter under X-ray environment.

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“…The work functions for fieldemission from CNT was experimentally reported at an early stage of research on this subject by Sinitsyn et al [19], Obraztsov et al [20] and several other researchers (see e.g., Ref. [21]). In several references therein and also in the subsequent studies discussed in Section 1, it has been explained how the experimentally obtained work function values can be employed in the Fowler-Nordheim (F-N) equation.…”

Section: Model Formulationmentioning

confidence: 89%