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News & Ideas
NANOELECTRONICS:
It goes both ways
Researchers are working toward the day when carbon
nanotubes will help create computing and other electronic systems
thousands of times faster than those in use today.
 One
challenge in making nanotubes work for electronic applications
is controlling their growth patterns. Ganapathiraman Ramanath
and Pulickel Ajayan, faculty of the Department of Materials Science
and Engineering, already are making headway in this area.
The two are the first to grow nanotubes into any
set of predetermined directions on silicon-based substrates. Their
work paves the way for making nanoscale devices that depend on
the connection of tiny wires in many directions. Preliminary results
of their work were published last year in Applied Physics Letters.
To allow the nanotubes to grow in different directions,
the researchers place pieces of silica on a silicon substrate.
A catalyst, called ferrocene, is introduced along with xylene,
the hydrocarbon that is the source of carbon. Carbon nanotubes
grow selectively on the silica, leaving the spaces of the silicon
layer bare.
The tubes grow in different directions depending
on the topography of the silica, Ramanath explains. For example,
if a piece of silica is carved into a one-micrometer-thick cylindrical
disc, the nanotubes will grow vertically on the silica’s
top surface while growing horizontally on its side.
“We can control nanotube growth with fine
detail by manipulating the topography and harnessing the way we
deliver the catalyst,” Ramanath says. “This is the first
time several key strategies have been combined to grow nanotubes
vertically and horizontally at the same time.”
CONTACT: Theresa Bourgeois, (518) 276-2840,
bourgt@rpi.edu
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