The Flattest Material In The World
by Phillip F. Schewe l Inside Science News Service
Physics Nobel Prize awarded for
discovering single-atom-thick sheets known as graphene.
WASHINGTON (ISNS) -- The Nobel Prize for
physics goes to Andre Geim and Konstantin Novoselov, both Russian-born
physicists now working at the University of Manchester in the U.K., for
their discovery of graphene.
Graphene is a sheet-like substance made of carbon atoms bonded
together in a repeating hexagonal pattern. It is the first essentially
two-dimensional material ever made.
Being the thinnest piece of matter in the world is just one of many
superlatives that can be applied to graphene. It is also the strongest
material known, about 100 times stronger than steel. Since a sheet of
graphene is only one atom thick, it is also transparent, and therefore
may play a role in the development of future electronic displays.
Some of the most interesting features of the material, from the point of
view of future applications, have to do with its electrical properties.
Electricity flows quickly through graphene and without losing much
energy along the way. This, coupled with the fact that it is relatively
easy to fabricate, makes graphene a candidate for replacing or enhancing
the integrated circuits that fill our computers today.
This circuitry
is often built around tiny etched bits of silicon that contain billions
of transistors, each of which can act like a switch which is either in
an ON or OFF position or, alternatively, can be set as a 0 or a 1 in the
binary logic used by computers to store and process information.
Graphene chips may be cheaper, faster, and easier to fabricate than
silicon chips.
One thing slowing graphene’s use in electronics is that it might be too
good a conductor of electricity. To act as a switch a transistor needs
to be turned off and on quickly. The semiconducting materials normally
used in transistors are, by their nature, poised halfway between
conducting and not conducting electricity. That is, by the input of a
very tiny signal they can allow an electrical current to pass through
(designating the ON position) or not pass through (the OFF position).
Pure graphene, being mainly a good conductor, cannot be switched on and
off. However, Geim and many other scientists believe that graphene can
be altered to solve this problem.
A Down-to-Earth Discovery
Geim and Novoselov and their colleagues discovered graphene in a very
humble way. They took a bit of Scotch tape and ran it across a piece of
bulk graphite, the same stuff used in pencils. The tape removed carbon
flakes that were many layers thick. But by repeated use of the tape,
thinner and thinner flakes could be produced, including some eventually
that were only a single layer thick. Microscopic pictures confirmed
what the human eye could not see.
Graphene is sometimes compared with carbon nanotubes, essentially pieces
of graphene rolled up into a straw shape. Both are very good conductors
of heat and of electricity. Both are quite strong.
"Graphene is the fundamental basis of all carbon nanostructures,
including carbon nanotubes, fullerenes, and lots more and has been the
holy grail to the research community for many years," said Mildred
Dresselhaus, a physicist at MIT and an expert on these various forms of
carbon. "It is great that Geim and Novoselov have now been recognized by
this wonderful prize for having the idea of actually producing graphene
in a simple way and for developing beautiful physics based on this
material."
The King of Sweden will bestow the award on Geim and Novoselov in a Stockholm ceremony in December.
In an offbeat footnote to today's announcement, Andre Geim has become
one of the few scientists to possess both a Nobel Prize and an Ig-Nobel
prize. The Ig-Nobels are sort of the anti-Nobel prize; they are awarded
partly as a joke and partly to make people think. Geim won an Ig-Nobel
in 2000 for levitating frogs using magnetic fields. This work was not
bogus, just strange.
Meanwhile, Geim and other researchers expect to find plenty of other
applications for graphene. Besides use in building materials or
electronics, graphene might emerge as a basis for chemical sensors and
for generators of terahertz-range light. This type of radiation, with
frequencies of about one trillion cycles per second, is somewhat
difficult to produce. It might be important as a new imaging tool since
human bodies are transparent at this frequency, making this sort of
light wave useful for security or medical scanning machines.
