Graphene's high-speed seesaw

Apr 30, 2013
Credit: University of Manchester

A new transistor capable of revolutionizing technologies for medical imaging and security screening has been developed by graphene researchers from the Universities of Manchester and Nottingham.

Writing in Nature Communications, the researchers report the first graphene-based transistor with bistable characteristics, which means that the device can spontaneously switch between two . 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.

Wonder material graphene is the world's thinnest, strongest and most , and has the potential to revolutionise a huge number of diverse applications; from smartphones and ultrafast broadband to drug delivery and . 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 just a few 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 ''. This process induces a rapid motion of which can lead to the emission of high-frequency .

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.

One of the researchers, Professor Laurence Eaves, 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.

Explore further: In-situ nanoindentation study of phase transformation in magnetic shape memory alloys

More information: Resonant tunnelling and negative differential conductance in graphene transistors, by L. Britnell, R. V. Gorbachev, A. K. Geim, L. A. Ponomarenko, A. Mishchenko, M. T. Greenaway, T. M. Fromhold, K. S. Novoselov and L. Eaves, Nature Communications, 2013.

Related Stories

Researchers move graphene electronics into 3D

Feb 02, 2012

In a paper published this week in Science, a Manchester team lead by Nobel laureates Professor Andre Geim and Professor Konstantin Novoselov has literally opened a third dimension in graphene research. Their ...

IBM introduces new graphene transistor

Apr 11, 2011

(PhysOrg.com) -- In a report published in Nature, Yu-ming Lin and Phaedon Avoris, IBM researchers, have announced the development of a new graphene transistor which is smaller and faster than the one they i ...

Two graphene layers may be better than one

Apr 27, 2011

(PhysOrg.com) -- Researchers at the National Institute of Standards and Technology have shown that the electronic properties of two layers of graphene vary on the nanometer scale. The surprising new results ...

Recommended for you

'Exotic' material is like a switch when super thin

Apr 18, 2014

(Phys.org) —Ever-shrinking electronic devices could get down to atomic dimensions with the help of transition metal oxides, a class of materials that seems to have it all: superconductivity, magnetoresistance ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

rsklyar
3 / 5 (2) May 01, 2013
How British swindlers are stealing in their cheating journals Nature Materials and "Measurement Science and Technology" at https://connect.i...sr/blogs (Impertinent cheating ... & A robbery ...)

More news stories

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...