(a) The assembly of a dense, full-coverage nanotube array, and (b) microscopic images of the aligned nanotubes. The study takes carbon nanotubes a step closer to replacing silicon in electronic devices. Image caption: Qing Cao, et al. ©2013 Macmillan Publishers Limited

Densest array of carbon nanotubes paves way toward post-silicon technology

February 14, 2013 by Lisa Zyga

Phys.org)—Single-walled carbon nanotubes may one day replace the silicon in electronics, but in order to do so, the nanotubes must be aligned in dense arrays for optimal performance. So far, the highest nanotube density is less than 50 tubes/?m, but in a new study researchers have broken this record by achieving a density of more than 500 tubes/?m. The higher density leads to better performance, bringing nanotubes a step closer to playing a role in post-silicon technologies.

The researchers, Qing Cao at the IBM T.J. Watson Research Center in Yorktown Heights, New York, and coauthors, have published their study on the dense arrays of carbon nanotubes in a recent issue of Nature Nanotechnology.

As the researchers explained, carbon nanotube-based electronics with the best electrical properties should have nanotubes that are purely semiconducting, that are well-aligned, and that form arrays with a density as high as possible, up to covering the entire substrate.

To meet these requirements, the researchers used a fabrication technique called the Langmuir-Schaefer method, which involves dispersing pre-enriched semiconducting nanotubes on a water surface. The floating nanotubes spread out to cover the whole surface as a result of the surface tension. Applying a compressive force assembles the nanotubes into well-ordered arrays, and the compression is stopped when the nanotube film becomes incompressible, which indicates that nanotube arrays have covered the entire surface. The resulting nanotube arrays have a 99% semiconducting purity and are aligned within 17° of one another.

Read more: Densest array of carbon nanotubes paves way toward post-silicon technology — phys.org.

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