Graphene pioneers follow in Nobel footsteps/Pavlosky - Carbon Flakes - 2000

01 Sep 2008

Two physicists from The University of Manchester who discovered the world’s thinnest material have scooped a major award for their work.

Professor Andre Geim FRS and Dr Kostya Noveselov of the Centre of Mesoscience and Nanotechnology have been awarded the prestigious Europhysics Prize for discovering graphene - and also their subsequent work to reveal its remarkable electronic properties.

Graphene is a one-atom thick gauze of carbon atoms resembling chicken wire. This incredible new material has rapidly become one of the hottest topics in materials science and solid-state physics.

Presented since 1975, the Europhysics Prize is one of the world’s most prestigious awards for condensed matter physics.

Many winners have subsequently been awarded the Nobel Prize in recognition of their achievements, including the last year Nobel Laureates Albert Fert, Peter Grünberg and Gerhard Ertl.

The Europhysics Prize recognizes recent work by one or more individuals, which, in the opinion of the European Physical Society, represents scientific excellence.

The 2008 Award was presented at the 22nd General Conference of the EPS Condensed Matter Division in Rome.

Aside from the prestige, Prof Geim and Dr Novoselov will share a cash prize of Euros 10,000.

Since the discovery of graphene in 2004, Prof Geim and Dr Novoselov have published numerous research papers in prestigious journals such as Science and Nature, which have demonstrated the exquisite new physics for the material and its potential in novel applications such as transistors just one atom thick and sensors that can detect just a single molecule of a toxic gas.

Prof Geim said: “To receive this award is a great honour. We have been working very hard and putting in long hours for the last five years. Hundreds of other researchers have now joined us in studying graphene.

“But still we have not yet explored even a tip of the iceberg. Graphene continues to surprise us beyond our wildest imagination.

“It works like a magic wand – whatever property or phenomenon you address with graphene, it brings you back a sheer magic.

“A couple of years ago, I was rather pessimistic about graphene-based technologies coming out of research labs any time soon. I have to admit I was wrong. They are coming sooner rather than later.

“In ten years time I believe the word graphene will be as widely known to the public as silicon.”

Source

United States Patent	6,819,034
Pavlovsky	November 16, 2004

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Carbon flake cold cathode

Abstract

A field emission cold cathode utilizes a film of carbon flake field emitters deposited thereon. The carbon flakes may exhibit rolled edges, but are still sufficient to provide improved field emission characteristics. A cold cathode using such carbon flake field emitters can be utilized to produce afield emission flat panel display, which can be implemented for use with a computer system.

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Inventors:	Pavlovsky; Igor (Austin, TX)
Assignee:	SI Diamond Technology, Inc. (Austin, TX)
Appl. No.:	09/642,955
Filed:	August 21, 2000

BACKGROUND INFORMATION

Carbon flake is a carbon material with a graphitic structure. It can be as thin as one or more layers of sp.sup.2 -bonded carbon atoms (graphite layers), and can be very long in two other dimensions. The length of a flake can be on the order of microns, whereas the thickness is on the order of nanometer or tens of nanometers. Thus, the aspect ratio for this material is very high. A flake, by its nature, is a system of ordered or turbostratic graphite layers. Carbon flakes fall into a class of nanostructured carbon materials. The flakes can be grown by several methods that fall into the following categories: 1. DC Glow Discharge. This method involves a direct current glow discharge between two electrodes in a gas environment. The plasma between the two electrodes is of the order of 1000.degree. C. or higher. This method produces carbon flakes along with other types of carbon materials such as carbon nanotubes. This method is used for depositing directly onto a substrate. 2. Thermal CVD (Chemical Vapor Deposition) Method. In this method, a carbon precursor gas and a substrate are heated to a temperature of 600.degree. C. and higher while thermal decomposition of the precursor is observed. The substrate has a catalyst on the working surface, which gives rise to growing carbon structures like carbon nanotubes and carbon flakes. A bias voltage can be used to make carbon nanostructures grow straight. This method is used for depositing directly onto a substrate.


Referring to FIG. 4, there is illustrated a cold cathode configured in accordance with the present invention. A substrate 101 has a conductor material 102 deposited thereon. Then carbon flakes 103-105 are grown on top of the conductor material 102. The carbon flake field emitters 103-105 can be grown by a plasma-assisted chemical vapor deposition ("CVD") method using a mixture of hydrogen (H.sub.2) and methane (CH.sub.4) or other hydrocarbon gas as a carbon precursor. The substrate 102 has a temperature of at least 400.degree. C., and is heated by a heater, or by adjacent plasma, or by hot carbon containing gas. The substrate 102 is cooled if its temperature is too high to form the flakes 103-105. During decomposition of carbon containing gas, the carbon atoms, or bonded carbon atoms, or carbon radicals assemble and form an sp.sup.2 -bonded carbon structure initiated on the substrate. The carbon radicals can further decompose leaving the carbon atoms bonded to the growing flake. The growth process occurs on the edges of the flakes 103-105 provided that flake is growing in lateral dimensions as new carbon atoms are bonded. This carbon structure 103-105 comprises the layers of sp.sup.2 -bonded atoms of carbon. The layers can be stacked together to form thicker flakes. During decomposition, gas species other than carbon may incorporate as defects in carbon structure. Such defects, as well as intrinsic defects of carbon structure may cause irregularities in this structure and, in turn, cause the flake bending.

What is claimed is:

1. An apparatus comprising: a substrate; a film of carbon flakes deposited on the substrate.

Source

2000 is way earlier than 2004! Let's give credit where credit is due.

emails:
1)

from	donpat/donpatent/nanopatent
to		kostya@manchester.ac.uk
date		Mon, Sep 1, 2008 at 9:36 AM
subject		Fwd: Geim, graphene and Pavlovsky and credit where credit is due
mailed-by		gmail.com

Please show this to Prof Geim and ask him what he thinks. What do you think? I would have sent this to Geim but can't find an email address for him.

---------- Forwarded message ----------
From: donpat/donpatent/nanopatent <donpatent@gmail.com>
Date: Mon, Sep 1, 2008 at 9:14 AM
Subject: Geim, graphene and Pavlovsky and credit where credit is due
To: webteam@manchester.ac.uk

In re - http://www.manchester.ac.uk/aboutus/news/display/?id=3907

FYI - please read:

http://donpatent.blogspot.com/2008/09/graphene-pioneers-follow-in-nobel.html
--
donpat/donpatent/nanopatent/nanotowin

2)

from Kostya Novoselov reply-to Konstantin.Novoselov@manchester.ac.uk to donpat/donpatent/nanopatent date Tue, Sep 2, 2008 at 9:29 AM subject RE: Geim, graphene and Pavlovsky and credit where credit is due

Dear Sir

I’m really grateful for the information about your patent on using turbostratic graphite for field emission cathode applications. I want to wish you a great success with it. Turbostratic graphite has been known for several decades and I’m glad that this interesting material will find its use in applications.

I would also like to draw your attention to several companies, which utilise similar idea in their products (for instance http://www.pfe-ltd.com/ ). I’m sure that you deserve some royalties there as well.

Sincerely yours

Kostya_____________________________________
Dr. Kostya Novoselov
School of Physics & Astronomy
Schuster Building
University of Manchester
Manchester M13 9PL
United Kingdom
Tel: +44-(0)161-275-41-19 (office)
Tel: +44-(0)161-275-42-41 (lab)
Fax: +44-(0)161-275-40-56
E-mail: kostya@manchester.ac.uk
Web: http://www.graphene.org
_____________________________________

3)

donpat/donpatent/nanopatent to Konstantin.Nov.

It's not my patent - it's my company's patent. What exactly is turbostatic graphite - I was under the impression that the patent referred to graphene flakes.

And did so at least before 2000, whereas your graphene development was ~ 2004.

Good luck with your claim to be the first.

I know PFE and they do not use graphene flakes.

(End of emails)

I looked for turbostratic graphite and graphene - this is of interest:
http://www-g.eng.cam.ac.uk/edm/Publications/pdf/Ferrari_PRL2006.pdf

Atom-thick material runs rings around silicon

19:00 17 April 2008

Enlarge image

Chunks of this atom-thick material just one nanometre across can function as transistors - the devices central to computing power (Image: Manchester University Mesoscopic Physics Group)

A leading contender to replace silicon as the basis for computing has made another step forward.

Transistors one atom thick and ten atoms wide have been made by UK researchers. They were carved from graphene, predicted by some to one day oust silicon as the basis of future computing.

For 40 years computing has been dominated by a rule of thumb named Moore's law, which predicts that the number of transistors on a chip will double roughly every two years.

Yet silicon, the material that has so far been used to keep up with Moore's law cannot form stable structures below 10 nanometres in size. And today's newest chips already have features just 45 nm across. The hunt is on for a replacement for silicon.

Graphene, a material made from flat sheets of carbon in a honeycomb arrangement is a leading contender. A team at the University of Manchester, UK, have now used it to make some of the smallest transistors ever. Devices only 1 nm across that contain just a few carbons rings.

Previous graphene transistors were significantly bigger – ribbons 10 nm across and many times longer.

Small proportions

"A big question has been which material to use for smaller transistors," says Kostya Novoselov, who with project co-leader Andre Geim discovered graphene in 2004. "This is one of the smallest transistors at the moment."

Graphene's carbon-carbon bonds are among the strongest in nature, and its honeycomb-like structure (see image, right) allows electrons to travel very rapidly. It also exhibits bizarre electrical properties that have fuelled an explosion of interest in the material.

Yet making transistors from graphene has proved difficult. The material usually lacks the switchable conductivity that transistors need to control electric current.

Novoselov and colleagues found that cutting small "quantum dots" of graphene can give it that property. Dots just a few nanometres across trap electrons thanks to quantum effects that become dominant at such small scales.

Tiny transistor

Applying a magnetic field to the smallest dots lets current flow again, making a switchable transistor. The smallest dots that worked as transistors contained as few as five carbon rings – around 10 atoms or 1nm wide.

There are other kinds of prototype transistors in this size range. But they usually need supercooling using liquid gas, says Novoselov. The new graphene devices work at room temperature.

Such prototypes are typically made by building one atom at a time, or wiring up individual molecules. Those approaches are complex and impractical, Novoselov says.

By contrast, the graphene transistors were made in the same way that silicon devices are, by etching them out of larger pieces of material. "That's their big advantage," he says.

Amazing result

"The most amazing result for me is that they were able to obtain quantum dots as small as 1 nm," says Antonio Castro Neto of Boston University, US. "This is shocking." "If you try to reduce the dimensions of any other structure, the structure would disintegrate before you reach these dimensions," Neto adds.

"There is no doubt in my mind that these structures can be used for technological applications," he says. "The electronic flexibility and structural stability, fundamental for modern device development, are unmatched in any other material on Earth." But working out how to manufacture graphene devices on a practical scale remains a challenge, he concludes.

Journal reference: Science (DOI: 10.1126/science.1154663) Link

Source

Carbon mesh pins down universal constant

Thursday, 17 April 2008

by Heather Catchpole

Cosmos Online

SYDNEY: The world's thinnest material can shed light on the exact measurement of one of the universe's fundamental physical constants, a new study reveals.

Researchers led by physicist Andre Geim from the University of Manchester in the U.K., used graphene – a sheet of carbon just one atom thick – to gauge the exact measurement of the fine structure constant, a fundamental physical constant defining the interaction between fast moving electric charges and light.

Their results were published online in the current edition of the journal Science Express, ahead of publication in the U.S. journal Science.

The fine structure constant was first introduced by physicists in attempts to understand atomic structure and has long mystified scientists because there seemed to be no natural mathematical relationship that described the constant, like a circle's circumference divided by its diameter describes the universal constant pi.

Foundations of life

In this new study, the U.K. and Portuguese researchers shone light through sheets of graphene and found that it absorbs a surprising amount of light considering its extreme thinness. The material's opacity is due to its molecular structure: a mesh of carbon atoms and bonds that looks something like chicken wire (when rolled up, graphene forms carbon nanotubes and when piled in layers it forms graphite).

They found that the exact value of light absorbed by graphene – 2.3 per cent of visible light – divided by pi gives the value of the fine structure constant (approximately 1/137). As the researchers point out, few other universal constants can be described so simply.

"We were absolutely flabbergasted when we realised that such a fundamental effect could be measured in such a simple way. One can have a glimpse of the very foundations of our universe just looking through graphene," said Geim, who was part of the team that discovered graphene in 2004.

"Change this fine-tuned number by only a few per cent and life would not be here because nuclear reactions in which carbon is generated from lighter elements in burning stars would be forbidden. No carbon means no life," he added.

Acting like light

Theoretical physicist Ross McKenzie from the School of Physical Sciences and the Centre for Organic Photonics and Electronics (COPE) at the University of Queensland, Australia, describes the research as "very beautiful".

"It's rare in condensed matter physics to get something so clean and elegant, particularly in the way the theory agrees with the experiment," he said.

Graphene can be used to calculate the fine structure constant because its crystal structure is unique among solids, according to McKenzie. As electron waves travel through the crystal, the symmetry of the carbon atoms forces the relationship between the electron wavelength and energy to be the same as the relationship for photons in light. As a result, the electrons effectively act as photons, but move at a much slower velocity. This property in turn leads to other unique properties that rely on the fine structure constant.

Chemical physicist Paul Meredith, also from COPE, said the research represents a "great leap forward" in terms of manipulating graphene. "The first step towards making a device, especially a nanoscopic device, is the ability to manipulate this material and they've cracked it," he said.

Graphene has very high conductivity so could be used in a variety of structured electronic materials, Meredith said. Possible uses include flexible transparent electronics or transparent electrodes for solar cells, as well as innovative uses in medicine.

Source