by Staff Writers
Wednesday, February 15, 2012
Graphene Electronics Moves to Three Dimensions
Graphene is moving into the third dimension simply because a two dimensional structure appears unsuitable for fabricating electronics because of huge current leakage. As I have posted once before, we are heading for a crystal like device and optimism now exists that it is all feasible.
Momentum in the field continues and the technology is soon to be in hardware everywhere. This was the major constraint.
We are seeing the end of the silicon age arrive.
Graphene electronics moves into a third dimension
by Staff Writers
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 research shows a transistor that may prove the missing link for graphene to become the next silicon.
Graphene - one atomic plane of carbon - is a remarkable material with endless unique properties, from electronic to chemical and from optical to mechanical.
One of many potential applications of graphene is its use as the basic material for computer chips instead of silicon. This potential has alerted the attention of major chip manufactures, including IBM,
Instruments and Intel. Individual transistors with very high frequencies (up to
300 GHz) have already been demonstrated by several groups worldwide. Samsung, Texas
Unfortunately, those transistors cannot be packed densely in a computer chip because they leak too much current, even in the most insulating state of graphene. This electric current would cause chips to melt within a fraction of a second.
This problem has been around since 2004 when the
researchers reported their
Nobel-winning graphene findings and, despite a huge worldwide effort to solve
it since then, no real solution has so far been offered. Manchester
now suggest using graphene not laterally (in plane) - as all the previous
studies did - but in the vertical direction. They used graphene as an electrode
from which electrons
tunnelled through a dielectric into another metal. This is called a tunneling diode. University
Then they exploited a truly unique feature of graphene - that an external voltage can strongly change the energy of tunnelling electrons. As a result they got a new type of a device - vertical field-effect tunnelling transistor in which graphene is a critical ingredient.
Dr Leonid Ponomarenko, who spearheaded the experimental effort, said: "We have proved a conceptually new approach to graphene electronics. Our transistors already work pretty well. I believe they can be improved much further, scaled down to nanometre sizes and work at sub-THz frequencies."
"It is a new vista for graphene research and chances for graphene-based electronics never looked better than they are now", adds Professor Novoselov.
Graphene alone would not be enough to make the breakthrough. Fortunately, there are many other materials, which are only one atom or one molecule thick, and they were used for help.
team made the transistors by combining graphene together with atomic planes of
boron nitride and molybdenum disulfide. The transistors were assembled layer by
layer in a desired sequence, like a layer cake but on an atomic scale. Manchester
Such layer-cake superstructures do not exist in nature. It is an entirely new concept introduced in the report by the
researchers. The atomic-scale
assembly offers many new degrees of functionality, without some of which the
tunnelling transistor would be impossible. Manchester
"The demonstrated transistor is important but the concept of atomic layer assembly is probably even more important," explains Professor Geim. Professor Novoselov added: "Tunnelling transistor is just one example of the inexhaustible collection of layered structures and novel devices which can now be created by such assembly.
"It really offers endless opportunities both for fundamental physics and for applications. Other possible examples include light emission diodes, photovoltaic devices, and so on."