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A cautionary
note in the use of carbon nanotubes as interconnects
Other Topics:
Nanotube Electrical Stimulation
University of Surrey’s
Advanced Technology Institute
September 16, 2008
Researchers at the University of Surrey’s Advanced
Technology Institute (UK) have used scanning tunneling
microscopy to confirm remarkable changes in the fundamental
electronic behaviour when double-walled carbon nanotubes are
subject to radial deformations and torsional strain. The
work reported in Nano Letters (reference below) reveals that
squashing and twisting a double-walled nanotube opens an
electronic band gap in an otherwise metallic system, which
has major ramifications on the use of carbon nanotubes for
electronic and NEMS applications. |
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Dr. Cristina Giusca, the lead author of the
paper said: “Fundamentally, the importance of the intershell
interaction in collapsed double-walled carbon nanotubes
points to the potential of a reversible metal-semiconductor
junction, which can have device applications, as well as
sending a cautionary note in the design of semiconductor
components based on carbon nanotubes”.
Since deformations can occur in response to the growth,
processing or characterization conditions of carbon
nanotubes, the work is of relevance in matters concerning
the characterisation of these structures, as the majority of
electronic transport measurements are performed using
various metals to contact the nanotubes, and the measured
values could in this case be affected by hidden
contributions.
Professor Ravi Silva, who leads the Advanced Technology
Institute, indicated that “These findings are of crucial
importance for the future integration of carbon nanotubes
with conventional existing electronic technologies, where,
for example, fabrication methods can induce deformations by
placing control electrodes on top of nanotubes or by
embedding the nanotubes into other structures”.
Chief among the use of these structures would be carbon
nanotubes as interconnects for the billion dollar
semiconductor industry which, according to the ITRS roadmap,
has yet to have a solution in place for 2012 integrated
circuits. Therefore, the deformation and mechanical
integrity study on a nano-scale of these essential
components would be of paramount importance.
Additionally, the work should pose an excellent challenge to
experimentalists to create ingenious ways which allow
deforming carbon nanotubes in a controllable manner to
easily provide the required metallic or semiconducting
features. As high conformational deformations, similar to
the ones presented in the paper, have been shown by
simulations to significantly enhance locally the chemical
reactivity of carbon nanotubes, controlled deformations
could also find prospective applications for potential
sensing devices. |
