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The basic
premise of "constructive destruction" is that in order to
construct a dense-array of semiconducting nanotubes, the
metallic nanotubes must be destroyed. This is accomplished with
an electric shockwave that destroys the metallic nanotubes,
leaving only the semiconducting nanotubes needed to build
transistors.
Here is how
it works:
The
scientists deposit ropes of "stuck together" metallic and
semiconducting nanotubes on a silicon-oxide wafer.
A
lithographic mask is projected onto the wafer to form electrodes
(metal pads) over the nanotubes. These electrodes act as a
switch to turn the semiconducting nanotubes on and off.
Using the
silicon wafer itself as an electrode, the scientists
"switch-off" the semiconducting nanotubes, which essentially
block any current from traveling through them.
The metal
nanotubes are left unprotected and an appropriate voltage is
applied to the wafer, destroying only the metallic nanotubes,
since the semiconducting nanotubes are now insulated.
The result
is a dense array of unharmed, working semiconducting nanotube
transistors that can be used to build logic circuits like those
found in computer chips.
Moore's Law says that the number of transistors
that can be packed on a chip doubles every 18 months, but many
scientists expect that within 10-20 years, silicon will reach
its physical limits, halting the ability to pack more
transistors on a chip. Transistors are a key building block of
electronic systems -- they act as bridges that carry data from
one place to another inside computer chips. The more transistors
on a chip, the faster the processing speed. This advance by IBM
scientists could have a profound impact on the future of chip
performance.
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