Growth of Ultrahigh Density Single-Walled Carbon Nanotube Forests by Improved Catalyst Design

Abstract

We have grown vertically aligned single-walled carbon nanotube forests with an area density of 1.5 × 10(13) cm(-2), the highest yet achieved, by reducing the average diameter of the nanotubes. We use a nanolaminate Fe-Al(2)O(3) catalyst design consisting of three layers of Al(2)O(3), Fe, and Al(2)O(3), in which the lower Al(2)O(3) layer is densified by an oxygen plasma treatment to increase its diffusion barrier properties, to allow a thinner catalyst layer to be used. This high nanotube density is desirable for using carbon nanotubes as interconnects in integrated circuits.

Influence of Packing Density and Surface Roughness of Vertically-Aligned Carbon Nanotubes on Adhesive Properties of Gecko-Inspired Mimetics

“…37 The others arrays consist of multiwalled tubes with diameters between 7 and 15 nm. For this range of larger diameters, the area densities span from 10 10 to ∼10 11 CNTs cm −2…”

“…The nanotube area density (i.e., number of nanotubes per unit area) is evaluated by the weight gain method. 37 The packing density (i.e., the fraction of the area covered by tubes) is evaluated by liquid-induced compaction. It involves soaking the nanotube samples thoroughly in ethanol and letting them dry in air.…”

“…The area density of the VACNTs is controlled by varying the thickness of the metal catalyst and the CNT CVD conditions, 35−38 and measured by the weight gain method and liquid-induced compaction method. 37,39 The overall surface roughness is analyzed by atomic force microscopy (AFM). The adhesion tests are carried out by a tensile setup (Figure 1) which records the pull-off forces the VACNTs exert from the target surface, both in normal and shear directions.…”

A Survey of Carbon Nanotube Interconnects for Energy Efficient Integrated Circuits

“…below 450 o C) with the ability to control nanotube dimensions, density (i.e. up to 10 13 CNTs cm -2 ) and patterning at specific locations [72], [73], [74], [75], [67], [119]. However, the design of catalyst to control nanotube chirality and especially for metallic nanotubes is very challenging [75], [76].…”

Data-driven understanding of collective carbon nanotube growth by in situ characterization and nanoscale metrology

“…37,61,[92][93][94][95] In the future, more improvements are expected in the area of catalyst design and process engineering toward more deterministic control on the overall CNT quality (straightness and defect density) and precise atomic structure, including both mono-chiral and monodisperse diameter distribution of as-grown CNTs.…”