Discovery Of Two-Dimensional Fabric Denotes Dawn Of New Materials Era
http://www.spacedaily.com/news/materials-04zzt.html
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Chernogolovka, Russia (SPX) Oct 22, 2004
Researchers at The University of Manchester and Chernogolovka, Russia have discovered the world's first single-atom-thick fabric, which reveals the existence of a new class of materials and may lead to computers made from a single molecule. The research is to be published in Science on 22 October.
The team led by Professor Andre Geim at The University of Manchester, has succeeded in extracting individual planes of carbon atoms from graphite crystals, which has resulted in the production of the thinnest possible fabric - graphene.

The resulting atomic sheet is stable, highly flexible and strong and remarkably conductive. The nanofabric belongs to the family of fullerene molecules, which were discovered during the last two decades, but is the first two-dimensional fullerene.

The researchers concentrate on the electronic properties of carbon nanofabric. By employing the standard microfabrication techniques used, for instance, in manufacturing of computer chips, the team has demonstrated an ambipolar field-effect transistor, which works under ambient conditions.

They found that the nanofabric exhibits a remarkable quality such that electrons can travel without any scattering over submicron distances, which is important for making very-fast-switching transistors.

In the quest to make the computer chip more powerful and fast, engineers strive to produce smaller transistors, shortening the paths electrons have to travel to switch the devices on and off. Ultimately, scientists envisage transistors made from a single molecule, and this work brings that vision ever nearer.

In terms of applications, the sort of quality demonstrated by graphene can only be compared with that demonstrated by some nanotubes.

Professor Geim commented: "As carbon nanotubes are basically made from rolled-up narrow stripes of graphene, any of the thousands of applications currently considered for nanotubes renowned for their unique properties can also apply to graphene itself."

Although the researchers are currently dealing with patches of graphene that are about ten microns across Professor Geim commented: "Computer engineers will need graphene wafers a few inches in size, before considering graphene as |"the next big thing". However, all the omens are good, as there are no fundamental limitations on the lateral size of carbon nanofabric."

Dr Novoselov added: "Only ten years ago carbon nanotubes were less than a micron long. Now, scientists can make nanotubes several centimetres long, and similar progress can reasonably be expected for carbon nanofabric too".

David Glover from University of Manchester Intellectual Property Ltd commented: "This is clearly an exciting breakthrough with huge potential, and with development graphene could soon compete in many niche markets where low energy consumption and high electron mobility are paramount requirements".

Radical fabric is one atom thick
A new class of material, which brings computer chips made from a single molecule a step closer, has been discovered by scientists.
Called graphene, it is a two-dimensional, giant, flat molecule which is still only the thickness of an atom.

The nanofabric's remarkable electronic properties mean that an ultra-fast and stable transistor could be made.

The physicists from the University of Manchester and Chernogolovka, Russia, published their research in Science.

"In my opinion, this is one of the most exciting thing to have happened in solid state physics in a decade," Professor Laurence Eaves, semi-conductor expert from the University of Nottingham told the BBC News website.

Graphene is part of the family of famous fullerene molecules, discovered in the last 20 years, which include buckyballs and nanotubes.

Their unusual electronic, mechanical and chemical properties at the molecular scale promise ultra-fast transistors for electronics, as well as incredibly strong, flexible and stable materials.

Ballistic promise

Scientists have been trying to exploit this for computing because smaller transistors mean the distances electrons have to travel become shorter, meaning faster speeds.


Conventional transistors rely on the semi-conducting characteristics of silicon which provide the switches that change the flow of current in computers and other electronics.
"All the recent progress has been on nanotubes for transistors. These are sheets of graphite molecules wrapped in a cylinder - like a chocolate cylinder you stick in your ice cream," explained Professor Laurence Eaves.

"Although these are interesting, because they are one-dimensional, they have limitations. Graphene is a plane transistor - flat sheets."

Professor Andre Geim, who leads the research team, explained that the material they have discovered could be thought of as millions of unrolled carbon nanotubes which have been stuck together to make an infinitely large sheet, an atom thick.

They showed that electrons could travel sub-micron distances without being scattered, which means fast-switching transistors.


"At the moment, the research is in early stages," Professor Geim said.
"The applications are too early to say, but the material is incredible. We have studied its electronic properties and no other material displays this."

He added: "People have been trying to make transistors faster and smaller. There is a Holy Grail of electronics that engineers call ballistic transistors - ultimately faster than anything."

A ballistic transistor is where electrons can shoot through without collisions, like a bullet. In other words, they have what is called a long mean free path - the distance a molecule travels without colliding into another.

Greater distances with nothing to collide with means faster speeds. Fewer collisions means less energy is lost or given off too.

Although they have not demonstrated a ballistic transistor yet, their experiments have shown that the material could, in theory, produce one.

The team are currently experimenting with relatively small sheets of the graphene nanofabric, 10s of microns across, but the sheets are still "large" in molecular terms.

The nanofabric would have to be produced in much larger wafers, a few inches in area, before electronics manufacturers could start using it.

But, said Professor Geim, judging by how quickly carbon nanotubes developed, graphene could be ready for industrial application in about 10 years.


Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/1/hi/sci/tech/3944651.stm