Graphene's high-speed seesaw

   
   
The new transistor developed by Nottingham and Manchester researchers
30 Apr 2013 16:00:00.000
A new transistor capable of revolutionising technologies for medical imaging and security screening has been developed by graphene researchers from the Universities of Nottingham and Manchester.

Writing in the journal Nature Communications, the researchers report the first graphene-based transistor with bistable characteristics, which means that the device can spontaneously switch between two electronic states. Such devices are in great demand as emitters of electromagnetic waves in the high-frequency range between radar and infra-red, relevant for applications such as security systems and medical imaging.

Bistability is a common phenomenon — a seesaw-like system has two equivalent states and small perturbations can trigger spontaneous switching between them. The way in which charge-carrying electrons in graphene transistors move makes this switching incredibly fast — trillions of switches per second.
Click here for full story

Wonder material

Wonder material graphene is the world’s thinnest, strongest and most conductive material, and has the potential to revolutionise a huge number of diverse applications; from smartphones and ultrafast broadband to drug delivery and computer chips. It was first isolated at The University of Manchester in 2004.

The device consists of two layers of graphene separated by an insulating layer of boron nitride just a few atomic layers thick. The electron clouds in each graphene layer can be tuned by applying a small voltage. This can induce the electrons into a state where they move spontaneously at high speed between the layers.

Because the insulating layer separating the two graphene sheets is ultra-thin, electrons are able to move through this barrier by ‘quantum tunnelling’. This process induces a rapid motion of electrical charge which can lead to the emission of high-frequency electromagnetic waves.

These new transistors exhibit the essential signature of a quantum seesaw, called negative differential conductance, whereby the same electrical current flows at two different applied voltages. The next step for researchers is to learn how to optimise the transistor as a detector and emitter.

Engineering tour-de-force

Professor Laurence Eaves in The University of Nottingham’s School of Physics and Astronomy, said: “In addition to its potential in medical imaging and security screening, the graphene devices could also be integrated on a chip with conventional, or other graphene-based, electronic components to provide new architectures and functionality.

“For more than 40 years, technology has led to ever-smaller transistors; a tour de force of engineering that has provided us with today’s state-of-the-art silicon chips which contain billions of transistors. Scientists are searching for an alternative to silicon-based technology, which is likely to hit the buffers in a few years’ time, and graphene may be an answer.”

“Graphene research is relatively mature but multi-layered devices made of different atomically-thin materials such as graphene were first reported only a year ago. This architecture can bring many more surprises”, adds Dr Liam Britnell, University of Manchester, the first author of the paper.

— Ends —

For up to the minute media alerts, follow us on Twitter or find out more on our Press Office blog

Notes to editors: The University of Nottinghamhas 42,000 students at award-winning campuses in the United Kingdom, China and Malaysia. It was ‘one of the first to embrace a truly international approach to higher education’, according to the Sunday Times University Guide 2013. It is also one of the most popular universities among graduate employers, one of the world’s greenest universities, and winner of the Times Higher Education Award for ‘Outstanding Contribution to Sustainable Development’. It is ranked in the UK's Top 10 and the World's Top 75 universities by the Shanghai Jiao Tong and the QS World Rankings.

More than 90 per cent of research at The University of Nottingham is of international quality, according to the most recent Research Assessment Exercise. The University aims to be recognised around the world for its signature contributions, especially in global food security, energy & sustainability, and health. The University won a Queen’s Anniversary Prize for Higher and Further Education for its research into global food security.

Impact: The Nottingham Campaign, its biggest ever fundraising campaign, will deliver the University’s vision to change lives, tackle global issues and shape the future. More news…

Story credits

More information is available from Laurence Eaves on +44 (0)115 951 5136, laurence.eaves@nottingham.ac.uk
 

Emma Thorne Emma Thorne - Media Relations Manager

Email: emma.thorne@nottingham.ac.uk Phone: +44 (0)115 951 5793 Location: University Park

Additional resources

No additional resources for this article

Media Relations - External Relations

The University of Nottingham
C Floor, Pope Building (Room C4)
University Park
Nottingham, NG7 2RD

telephone: +44 (0) 115 951 5798
email: communications@nottingham.ac.uk