Single sheets of graphene sandwiched between insulating layers can be used to produce electrical devices with distinctive new properties, researchers at The University of Manchester have shown. Writing in Nature Materials, the scientists show that graphene can be used as a building block to create new 3D crystal structures which are unconfined by what nature can produce.
This method may well open up a new aspect of physics research. The research shows that a new side-view imaging technique is able to be used to visualize the individual atomic layers of graphene inside the devices they have built. They discovered that the structures were nearly perfect, even when in excess of 10 different layers were used to build the stack.
This startling outcome indicates that the newest techniques of isolating graphene could be a huge leap forward for engineering at the atomic level. This improvement gives more authority to graphene’s suitability as a major component in the next generation of computer chips.
The researchers’ side-view imaging approach works by first extracting a thin slice from the centre of the device, and is similar to cutting through a rock to reveal the geological layers or slicing into a chocolate cake to reveal the individual layers of icing.
The scientists used a beam of ions to cut into the surface of the graphene and dig a trench on either side of the section they wanted to isolate. They then removed a thin slice of the device. Transmission electron microscopy (TEM) was used for imaging.
Graphene Thinnest Material Known
Marvel material graphene is a two dimensional material made up of a single layer of carbon atoms, ordered in a honeycomb or chicken wire structure. It is the thinnest material in the world but is also one of the strongest. Not only that, but it conducts electricity as efficiently as copper and outperforms all other materials as a conductor of heat.
Graphene is nearly totally transparent, nevertheless it is so dense that even helium cannot pass through it.
The 2010 Nobel prize for Physics was awarded to Professor Andre Geim and Professor Kostya Novoselov, for demonstrating graphenes extraordinary properties. A state-of-the-art National Graphene Institute is currently being built at The University of Manchester to continue graphene research.
“The difference is that our slices are only around 100 atoms thick and this allows us to visualize the individual atomic layers of graphene in projection”, said Dr Sarah Haigh, from The University of Manchester’s School of Materials.
“We have found that the observed roughness of the graphene is correlated with their conductivity. Of course we have to make all our electrical measurements before cutting into the device. We were also able to observe that the layers were perfectly clean and that any debris left over from production segregated into isolated pockets and so did not affect device performance. We plan to use this new side view imaging approach to improve the performance of our graphene devices.”
1. Cross-sectional imaging of individual layers and buried interfaces of graphene-based heterostructures and superlattices
S. J. Haigh, A. Gholinia, R. Jalil, S. Romani, L. Britnell, D. C. Elias, K. S. Novoselov, L. A. Ponomarenko, A. K. Geim & R. Gorbachev
Nature Materials (2012) doi:10.1038/nmat3386