A new study presents new techniques scientists have developed to assemble graphene.
Graphene, a crystalline form of carbon, is the subject of many 2D material researches particularly in device applications and electrical behaviors analysis. However these earlier experiments were exposed to natural contamination, which apparently are linked together.
Cory Dean, lead researcher and a postdoctoral fellow at Columbia University, developed new techniques to resolve electrical contact and environmental contamination that hinders further development of the material. Scientists were able to prove that electrical contact with a 2D atomic substance may be done on its 1D edge instead of the traditional means of making the contact at the top.
The new technique allows the graphene to bond with the surface of an outside plane under a 2D insulator.
To fully encapsulate the two-dimensional graphene, the scientists packed it in between thin boron nitride crystalline insulation, wherein the crystal layers are piled one after another.
"Our approach for assembling these heterostructures completely eliminates any contamination between layers which we confirmed by cross-sectioning the devices and imaging them in a transmission electron microscope with atomic resolution," Dean said in a statement.
These were observed within room temperatures, where the resistance matches with bulk 3D sheet resistance which is less than the performance of other types of metal substances.
In the experiment, the electrons moved together without dispersion, which is an event called ballistic transport. This phenomenon previously detected within one-micrometer sized samples was also observed by the scientists in larger models measuring at most 20 micrometers.
"So far this is limited purely by device size, indicating that the true 'intrinsic' behavior is even better," explained by Dean.
The team's graphene model provides two types of assembly techniques – the one-dimensional edge contact and the layer-by-layer assembly -which when used together provides the most uncontaminated graphene as of this time. With this novel technique at assembly, scientists can now proceed with experiments on layered materials without the usually destructive interface contamination.
"With so much current research focused on developing new devices by integrating layered 2D systems, potential applications are incredible, from vertically structured transistors, tunneling based devices and sensors, photoactive hybrid materials, to flexible and transparent electronics," said Dean.
The study was published in the Nov. 1 issue of the online journal Science.
