Large-scale synthesis of arrays of high-aspect-ratio rigid vertically aligned carbon nanofibres

Melechko, Anatoli V.; McKnight, Timothy E.; Hensley, Dale K.; Guillorn, Michael A.; Borisevich, Albina Y.; Merkulov, Vladimir I.; Lowndes, D. H.; Simpson, Michael L.

doi:10.1088/0957-4484/14/9/318

Cited by 66 publications

(64 citation statements)

References 25 publications

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“…Energy-Dispersive-X-ray (EDX) analysis performed by Melechko et al, has indicated the presence of a sheath of SiNx on the CNF sidewalls for tubes synthesized on Si. 26 The presence of such a dielectric coating on the sidewalls of the CNFs grown on Si would explain the data we obtained in curve 3 of Fig. 7.…”

Section: Electrical Actuation In Vertically Oriented Carbon Nanofiberssupporting

confidence: 51%

Carbon-based nano-electro-mechanical systems

et al. 2010

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We provide an overview of our work where carbon-based nanostructures have been applied to twodimensional (2D) planar and three-dimensional (3D) vertically-oriented nano-electro-mechanical (NEM) switches. In the first configuration, laterally oriented single-walled nanotubes (SWNTs) synthesized using thermal chemical vapor deposition (CVD) were implemented for forming bridge-type 2D NEMS switches, where switching voltages were on the order of a few volts. In the second configuration, vertically oriented carbon nanofibers (CNFs) synthesized using plasma-enhanced (PE) CVD have been explored for their potential application in 3D NEMS. We have performed nanomechanical measurements on such vertically oriented tubes using nanoindentation to determine the mechanical properties of the CNFs. Electrostatic switching was demonstrated in the CNFs synthesized on refractory metallic nitride substrates, where a nanoprobe was used as the actuating electrode inside a scanning-electron-microscope. The switching voltages were determined to be in the tens of volts range and van der Waals interactions at these length scales appeared significant, suggesting such structures are promising for nonvolatile memory applications. A finite element model was also developed to determine a theoretical pull-in voltage which was compared to experimental results.

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Section: Electrical Actuation In Vertically Oriented Carbon Nanofiberssupporting

confidence: 51%

Carbon-based nano-electro-mechanical systems

et al. 2010

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“…II C 3 and ͑2͒ compounds of redeposited substrate material, for instance silicon, which can react with the nitrogen from the ammonia etchant gas to form Si x N y coatings on the surface. 66,70,89 The sidewall deposition of carbon films was first reported by Chen et al in a high temperature, high pressure, hot filament PECVD process. 87 They observed formation of conical structures, shown in Fig.…”

Section: In Situ Pecvd Coatings and Surface Modificationmentioning

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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“…While further work is necessary to investigate the effects of other growth parameters, it is clear that growths conducted at higher initial currents can be used to synthesize essentially defect-free single row barriers and ordered nanofiber arrays with reasonable yields. The taper, or conical nature of the fibers, results from sidewall deposition of silicon nitride during the deposition process as discussed by Melechko et al [7] In Fig. 5, an ordered fiber array is shown next to a random nanofiber forest, contrasting the difference in density and consistency of morphology of fibers grown from catalyst particles resulting from discrete patterning (ordered array) and the break-up of a catalyst thin film (random forest).…”

Section: Resultsmentioning

confidence: 93%

“…The impact of pressure, temperature, gas ratio, choice of catalyst material, and even catalyst geometry on fiber morphology and growth rate have been explored [7][8][9][10][11][12][13][14][15][16]. Furthermore, the integration of ensembles of individual fibers and stochastic nanofiber forests into functional devices for electrochemical and biochemical sensing [17][18][19][20][21][22][23][24][25][26], gated-cathode field emitters [27][28][29], barriers to material transport [30][31][32] and templates for the synthesis of nanofluidic nozzles, or nanopipes [33,34], has also been described.…”

Section: Introductionmentioning

confidence: 99%

Positional control of catalyst nanoparticles for the synthesis of high density carbon nanofiber arrays

Retterer

Melechko

Hensley

et al. 2008

Carbon

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Precise arrangement of nanoscale elements within larger systems, is essential to controlling higher order functionality and tailoring nanophase material properties. Here, we present findings on growth conditions for vertically aligned carbon nanofibers that enable synthesis of high density arrays and individual rows of nanofibers, which could be used to form barriers for restricting molecular transport, that have regular spacings and few defects. Growth through plasma-enhanced chemical vapor deposition was initiated from precisely formed nickel catalyst dots of varying diameter and spacing that were patterned through electron beam lithography. Nanofiber growth conditions, including power, precursor gas ratio, growth temperature and pressure were varied to optimize fiber uniformity and minimize defects that result from formation and migration of catalyst particles prior to growth. It was determined that both catalyst dot diameter and initial plasma power have a considerable influence on the number and severity of defects, while growth temperature, gas ratio (C 2 H 2 :NH 3 ) and pressure can be varied within a considerable range to fine-tune nanofiber morphology.

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Large-scale synthesis of arrays of high-aspect-ratio rigid vertically aligned carbon nanofibres

Cited by 66 publications

References 25 publications

Carbon-based nano-electro-mechanical systems

Carbon-based nano-electro-mechanical systems

Surface characterization and functionalization of carbon nanofibers

Positional control of catalyst nanoparticles for the synthesis of high density carbon nanofiber arrays

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