Scientists researching graphene stumble upon surprising result
Researchers from the United Kingdom have uncovered an unexpected characteristic of graphene by demonstrating a method that uses graphene as a building block to create new three-dimensional (3D) crystal structures which are not confined by what nature can produce.
Set out in the journal Nature Materials, their method involves sandwiching individual graphene sheets between insulating layers in order to produce electrical devices with unique new properties.
The hope is that this new method will open up a whole new dimension of physics research.
Graphene is a 2D material consisting of a single layer of carbon atoms arranged in a honeycomb or chicken wire structure. It is the thinnest material in the world and yet is also one of the strongest. It conducts electricity as efficiently as copper and outperforms all other materials as a conductor of heat.
The scientists proved that a new side-view imaging technique can be used to visualise the individual atomic layers of graphene within the devices they have built. They found that the structures were almost perfect even when more than 10 different layers were used to build the stack.
This development further proves 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. The team likens this 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.
Lead study author Dr Sarah Haigh, from the University of Manchester, comments: 'Our slices are only around 100 atoms thick and this allows us to visualise the individual atomic layers of graphene in projection.
'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.'
Two of the study researchers, Andre Geim and Konstantin Novoselov, both from the University of Manchester, were awarded the Nobel Prize in Physics in 2010 for their 'groundbreaking experiments regarding the two-dimensional material graphene'.
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Document Reference: Haigh, S.J., et al. 'Cross-sectional imaging of individual layers and buried interfaces of graphene-based heterostructures and superlattice', Nature Materials, 2012. doi:10.1038/NMAT3386
Subject Index: Coordination, Cooperation; Innovation, Technology Transfer; Materials Technology; Scientific Research