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Controlling the electronic properties of carbon nanotube circuits

Philip G. Collins*, Phaedon Avouris

IBM T.J. Watson Research Center,
Yorktown Heights, New York 10598 USA

This is an abstract for a presentation given at the
Ninth Foresight Conference on Molecular Nanotechnology.
There will be a link from here to the full article when it is available on the web.

 

Ideally, carbon nanotubes are unique, low-dimensional conductors with either metallic or semiconducting properties. In practice, however, these hollow cylinders have a strong tendency to agglomerate as they form, resulting in either large, multi-walled nanotubes (MWNTs) with many concentric carbon shells or else bundles, or "ropes," of aligned single-walled nanotubes (SWNTs). Both aggregates are complex composite conductors incorporating many weakly-coupled nanotubes, each having a different electronic structure. This complexity remains the primary difficulty in both understanding and developing nanotube-based electronic devices.

We have demonstrated a simple and reliable method for tailoring the properties of these bundled nanotubes (1). The method uses selective oxidation to remove single carbon shells from either MWNTs or SWNT bundles (2), and it allows us, for the first time, to take advantage of the full complexity of these conductors. For instance, we can step through and individually characterize the concentric shells of a MWNT. By choosing from among the different shells, we convert adjacent segments of a MWNT into either metallic or semiconducting conductors by design. By comparing the transport behavior of a MWNT before and after the removal of single carbon shells, we can also quantitatively address each shell's contribution and the issue of inter-shell conductance.

With SWNT ropes, similar selectivity allows us separate semiconducting and metallic carbon shells. Using this technique, we have produced entire arrays of high performance, nanoscale field-effect transistors (FETs) based solely on the fraction of semiconducting SWNTs. These procedures sidestep the need for selective nanotube synthesis and allow unprecedented flexibility in the creation of nanoscale electronic devices, both for their study and for practical applications.

References
  1. P.G. Collins, M. Arnold, and Ph. Avouris, Science 292 (2001) p. 706.
  2. P.G. Collins, R. Martel, and Ph. Avouris, Physical Review Letters, 86 (2001) p. 3128.

*Corresponding Address:
Philip G. Collins
Covalent Materials
1295A 67th St., Emeryville, CA 94608 USA
phone: 510-428-5323
fax: 510-658-0425
email: pg_collins@excite.com
http://www.covalentmaterials.com



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