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CX2SA > TECH 16.08.05 06:47l 68 Lines 3307 Bytes #999 (0) @ WW
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Subj: Y-shaped nanotubes are ready..
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Sent: 050816/0531Z @:CX2SA.LAV.URY.SA #:23006 [Minas] FBB7.00e $:23006_CX2SA
From: CX2SA@CX2SA.LAV.URY.SA
To : TECH@WW
Y-shaped nanotubes are ready-made transistors
=============================================
Tiny tubes of carbon, crafted into the shape of a Y, could revolutionise the
computer industry, suggests new research.
The work has shown that Y-shaped carbon nanotubes are easily made and act as
remarkably efficient electronic transistors - the toggles used to control the
flow of electrons through computer circuits.
But the nanotransistors are just a few hundred millionths of a metre in size
-roughly 100 times smaller than the components used in today's microprocessors.
They could, therefore, be used to create microchips several orders of magnitude
more powerful than the ones used in computers today, with no increase in chip
size.
Prab Bandaru and colleagues at the University of California in San Diego, and
Apparao Rao, of Clemson Univeristy in South Carolina, both in the US, started
by growing ordinary carbon nanotubes through chemical vapour deposition.
But they added iron-titanium particles to spur the growth of an extra nanotube
branch attached to the main stem. The overall structure assumed a Y-shape and
the catalyst particles were absorbed into the tubes at the branching point.
Experiments then showed that applying a voltage to the stem of the Y precisely
controls the flow of electrons through the other two branches. The switching
capacity of these nanostructures is, in comparable to that of today's silicon
transistors.
And, whereas current silicon transistors have been shrunk to around 100
nanometres, the Y-shaped nanotubes measure just tens of nanometres in size.
Eventually, they could even be shrunk to just a few nanometres, the researchers
suggest.
Previous efforts to construct transistors using carbon nanotubes have involved
attaching the tubes to larger silicon elements. By contrast, the Y-junction
transistors are made entirely from carbon nanotubes.
New era
-------
"The transistor is fully self-contained," Bandaru told New Scientist. "The
discovery heralds a new era of nanoelectronics in that functionality can be
harnessed using all-carbon devices."
Bandaru says the main remaining worry is how to manufacture complex nanotube
-based circuitry reliably. Nonetheless, he is optimistic about the future of
nanotube-based electronics.
"One must remember that for the Pentium chips which now have over 500 million
transistors, the progenitor was a simple integrated circuit with two
transistors in 1958," Bandaru says. "We are probably at the same stage with Y
-junctions and the future looks good."
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