Influence of the growth temperature on the first and second-order Raman band ratios and widths of carbon nanotubes and fibers

Vollebregt, Sten; Ishihara, Ryoichi; Tichelaar, F.D.; Hou, Yu; Beenakker, C.I.M.

doi:10.1016/j.carbon.2012.03.026

Cited by 191 publications

(143 citation statements)

References 29 publications

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“…Other researchers have reported similar densities in the order of 10 10 toward 10 11 tubes cm -2 . [33][34][35] Furthermore, a representative volume element which consists of multiple interacting CNTs can be defi ned as a unit-cell for the purpose of simulation, see Figure 1 .…”

Section: Introductionmentioning

confidence: 99%

Effects of Nanostructure and Coating on the Mechanics of Carbon Nanotube Arrays

Poelma

Fan

et al. 2016

Adv Funct Materials

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Nanoscale materials are one of the few engineering materials that can be grown from the bottom up in a controlled manner. Here, the effects of nanostructure and nanoscale conformal coating on the mechanical behavior of vertically aligned carbon nanotube (CNT) arrays through experiments and simulation are systematically investigated. A modeling approach is developed and used to quantify the compressive strength and modulus of the CNT array under large deformation. The model accounts for the porous nanostructure, which contains multiple CNTs with random waviness, van der Waals interactions, fracture strain, contacts, and frictional forces. CNT array micropillars are grown and their porous nanostructure is controlled by the infiltration and deposition of thin conformal coatings using chemical vapor deposition. Flat‐punch nanoindentation experiments reveal significant changes in material properties as a function of coating thickness. The simulations explain the experimental results and show the novel failure transition regime that changes from collective CNT buckling toward structural collapse due to fracture. The compressive strength and the elastic modulus increase exponentially as a function of the coating thickness and demonstrate a unique dependency on the CNT waviness. More interestingly, a design rule is identified that predicts the optimum coating thickness for porous materials.

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Section: Introductionmentioning

confidence: 99%

Effects of Nanostructure and Coating on the Mechanics of Carbon Nanotube Arrays

Poelma

Fan

et al. 2016

Adv Funct Materials

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“…Raman spectroscopy is a powerful technique for investigating the crystallinity of the CNT 18 , and can for instance be used to optimize the CNT growth parameters in order to obtain the highest quality CNT. I-V measurements were performed using four point probe structures and are displayed in Figure 5.…”

Section: Representative Resultsmentioning

confidence: 99%

“…As the different Raman bands are close to each-other deconvolution of the bands is necessary, as described elsewhere 18 . From the Raman data in Figure 4 it is apparent that a strong D and D' band can be observed, which are caused by Raman scattering with defects, while the G band is related to the C-C bond.…”

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confidence: 99%

“…It is known that a low growth temperature in general results in a lower CNT quality 18 . Usually the D over G intensity ratio (I D/G ) is used to assess the quality of graphitic materials, which is 1.1 in Figure 4.…”

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confidence: 99%

“…Due to the very low growth temperature, the CNT in this work appear to have a crystallinity below this threshold 16 . In these cases the full-width at half maximum of the D band can be used to compare CNT samples fabricated at different process conditions 18 . It can be expected that the low quality of the CNT will significantly influence the electrical performance.…”

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confidence: 99%

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Fabrication of Low Temperature Carbon Nanotube Vertical Interconnects Compatible with Semiconductor Technology

Vollebregt

Ishihara

2015

JoVE

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We demonstrate a method for the low temperature growth (350 °C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive thin-films. Due to the low growth temperature, the process allows integration with modern low-κ dielectrics and some flexible substrates. The process is compatible with standard semiconductor fabrication, and a method for the fabrication of electrical 4-point probe test structures for vertical interconnect test structures is presented. Using scanning electron microscopy the morphology of the CNT bundles is investigated, which demonstrates vertical alignment of the CNT and can be used to tune the CNT growth time. With Raman spectroscopy the crystallinity of the CNT is investigated. It was found that the CNT have many defects, due to the low growth temperature. The electrical current-voltage measurements of the test vertical interconnects displays a linear response, indicating good ohmic contact was achieved between the CNT bundle and the top and bottom metal electrodes. The obtained resistivities of the CNT bundle are among the average values in the literature, while a record-low CNT growth temperature was used. Video LinkThe video component of this article can be found at

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High Quality Carbon Nanotubes on Conductive Substrates Grown at Low Temperatures

Ahmad

Anguita

Stolojan

et al. 2015

Adv Funct Materials

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Keywords: nanomaterials, carbon nanotubes, photothermal chemical vapor deposition, low temperature growth 2 For carbon nanotubes (CNTs) to be exploited in electronic applications the growth of high quality material on conductive substrates at low temperatures (< 450 o C) is required. CNT quality is known to be strongly degraded when growth is conducted on metallic surface at low temperatures using conventional chemical vapor deposition (CVD). Here, we demonstrate production of high quality vertically-aligned CNTs at low substrate temperatures (350 -440 o C) on conductive TiN thin film using photo-thermal CVD by confining the heat required for growth to just the catalyst using an array of optical lamps and by optimizing the thickness of the TiN under-layer. The thickness of the TiN plays a crucial role in determining various properties including diameter, material quality, number of shells and metallicity. The highest structural quality with a visible Raman D-to G-band intensity ratio as low as 0.13 is achieved for 100 nm TiN thickness grown at 420 o C; a record low value for low temperature CVD grown CNTs. Electrical measurements of high density CNT arrays show the resistivity to be 1.25×10 -2 Ωcm represents some of the lowest values reported. Finally, the broader aspects of using this approach as a scalable technology for carbon nanomaterial production are also discussed.3

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Influence of the growth temperature on the first and second-order Raman band ratios and widths of carbon nanotubes and fibers

Cited by 191 publications

References 29 publications

Effects of Nanostructure and Coating on the Mechanics of Carbon Nanotube Arrays

Effects of Nanostructure and Coating on the Mechanics of Carbon Nanotube Arrays

Fabrication of Low Temperature Carbon Nanotube Vertical Interconnects Compatible with Semiconductor Technology

High Quality Carbon Nanotubes on Conductive Substrates Grown at Low Temperatures

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