Preferential Growth of Single-Walled Carbon Nanotubes with Metallic Conductivity
Avetik R. Harutyunyan,1,*
Gugang Chen,1
Tereza M. Paronyan,2
Elena M. Pigos,1
Oleg A. Kuznetsov,1
Kapila Hewaparakrama,2
Seung Min Kim,3,4
Dmitri Zakharov,4
Eric A. Stach,3,4
Gamini U. Sumanasekera2
Single-walled carbon nanotubes can be classified as either metallic
or semiconducting, depending on their conductivity, which is
determined by their chirality. Existing synthesis methods cannot
controllably grow nanotubes with a specific type of conductivity.
By varying the noble gas ambient during thermal annealing of
the catalyst, and in combination with oxidative and reductive
species, we altered the fraction of tubes with metallic conductivity
from one-third of the population to a maximum of 91%. In situ
transmission electron microscopy studies reveal that this variation
leads to differences in both morphology and coarsening behavior
of the nanoparticles that we used to nucleate nanotubes. These
catalyst rearrangements demonstrate that there are correlations
between catalyst morphology and resulting nanotube electronic
structure and indicate that chiral-selective growth may be possible.
2 Department of Physics and Astronomy, University of Louisville, Louisville, KY 40292, USA.
3 School of Materials Engineering, Purdue University, 701 Northwestern Avenue, West Lafayette, IN 47907, USA.
4 Birck Nanotechnology Center, Purdue University, 1205 West State Street, West Lafayette, IN 47907, USA.
* To whom correspondence should be addressed. E-mail: aharutyunyan{at}honda-ri.com
