Bengaluru, Apr 25: Researchers from the Indian Institute of Science (IISc) have successfully produced a new type of electrical conductor that was theoretically predicted 20 years ago.
A team led by Dr. Arindam Ghosh, Associate Professor in the Department of Physics at IISc, successfully produced graphene that is single or few layers thick to conduct current along one particular edge, the zigzag edge, which has a unique property of allowing the flow of charge without any resistance at room temperature and above.
Many groups across the world have been trying to access these edges since the emergence of graphene in 2004, but have largely been unsuccessful because of the reason that when current flows through graphene, it flows through both edge as well as the bulk.
“We succeeded in this endeavour by creating the bulk part of graphene extremely narrow (less than 10 nanometres thick), and hence highly resistive, thus forcing the current flow through the edge alone,” says Arindam Ghosh.
“While the bulk is insulating, the edge alone has the ability to conduct because of the unique quantum mechanics of the edge. Because of the zigzag orientation of carbon atoms, the electron wave on each carbon atom overlaps and forms a continuous train of wave along the edge. This makes edge conducting,” explained Prof. Ghosh.
There are currently several chemical methods to produce very narrow graphene nanoribbons. But these chemicals tend to destroy the edges. “So the challenge is to produce graphene nanoribbons using chemicals that do not destroy the edges,” he added. “We believe that this successful demonstration of the dissipation-less edge conduction will act as great incentive to develop new chemical methods to make high-quality graphene nanoribbons or nano-strips with clean edges.”
The results of the study were published online in the journal Nature Nanotechnology on April 3, 2017. The team consisted of 8 members of the Department of Physics at IISc and one from the University of Alabama, along with Arindam Ghosh.