Many groups of researchers are working
to make plastic electronics that are as fast as today's silicon electronic
components. Powerful plastic electronics promise to enable flexible, inexpensive
and very-large area computer screens.
Researchers from the U.S. Naval Research Laboratory and Applied
Nanotech, Inc. have moved a step forward with an electronic material that
is a mix of carbon nanotubes and polymer, or plastic. Carbon nanotubes
are rolled-up sheets of carbon atoms that can be narrower than a single
nanometer. A nanometer is one millionth of a millimeter, or the span of
ten hydrogen atoms.
Key the potential usefulness of the researchers' material is its
electron mobility -- a measure of how quickly electrical current moves
through the device. Organic thin film transistors have electron mobilities
under 10 square centimeters per volt second. The single-crystal silicon
used in computer chips has a mobility of 1,500. The researchers' carbon
nanotube/polymer mix has an electron mobility of 150, according to the
The material promises to enable lightweight unbreakable displays
and inexpensive large-area screens, according to the researchers.
To make the material the researchers suspended nanotubes in a
liquid, put the liquid on a polyimide surface, and dried the liquid to
leave a random tangle of nanotubes. The researchers are working out ways
to print the material onto surfaces rather than using conventional microfabrication.
This would make it possible to manufacture large, inexpensive sheets of
The material's electron mobility could be boosted close to that
of single crystal silicon thin-film transistors if only semiconducting
rather than a mix of semiconducting and metallic nanotubes were used,
according to the researchers.
The material could be used practically in five to ten years, according
to the researchers. The work appeared in the January 17, 2005 issue of
Applied Physics Letters.
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View from the High Ground:
Xerox's Hervé Gallaire
on plastic speed circuits
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nanocrystal transistor shines
View from the High Ground Q&A
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