BY ITSELF, silicon is not an effective conductor.
It does not leave its electrons
free for smooth flow of information. To
make it less rigid, impurities are introduced
into a pure silicon chip. The
impurities free an electron or two and
make the element a better conductor.
This is called doping--a process essential
to creating the heart of every electronic
device.
Concentrations as small as one
atom of boron, arsenic or phosphorus
(impurities) per 100 million atoms of
silicon have been effective so far. But
with the world increasingly devising
chips smaller than a strand of human
hair, the definition of doping had to
change, too. This was the challenge
James Tour and his team of researchers
from the Rice University accepted.
The study published in the July issue
of the Journal of the American Chemical
Society suggests attaching a single layer
of molecules on to the surface of the silicon
chip, rather than mixing
them in, serves the same purpose
as doping but works better
at the nanolevel. For this,
the team bathed the nanosilicon
chip in the dopant solution,
just like one creates a
photographic film. "We call
it silicon with afterburners,"
said Tour who teaches
chemistry at Rice University.
The nanochips
have very little volume and you
have to deal with them accordingly," he
explained. Dopants mixed with silicon
in the usual way destroy its homoge -
neity and hamper conductivity.
Years of research into replacing silicon
with a better semiconductor has
yielded little. "So we decided to complement
silicon, rather than supplant it,"
said Tour. "This research gives the Intels
and the Samsungs of the world another
tool to try, and I guarantee you they'll
be trying it," he added.
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