Graphene has lately been the electronic industry’s spoiled kid – everybody wants to have a piece of the research, but few have the tools and inspiration to find something new. A team of researchers from the University of Arizona have found a material that can play the role of an insulator for the one atom-thick graphene layer. The team published their study in Nature Materials.
A sheet of carbon atoms linked in a hexagonal structure, graphene can be used in the tiniest of electronics and solar cells, and could be a milestone in the development of much more energy-efficient devices.
So far, researchers haven’t been able to find a substrate for graphene other than silicon oxide, which does a good job, but at the same time modifies the electronic properties of the graphene. How did the scientists discover that? Well, by analyzing graphene layers with a silicon background through a scanning tunneling microscope, they realized that there were bumps in the silicon structure as high as 1 nanometer and that in certain places, the silicon exhibited different electronic properties, which altered the graphene’s functionality.
“It’s basically like a piece of paper that has little crinkles in it,” said Brian LeRoy, an assistant professor of physics and senior author of the study. “But if you put the paper, in this case the graphene, on boron nitride, it’s much flatter. It smooths out the bumps by an order of magnitude.”
Having a structure almost identical to graphene, a material called boron nitride seems to be the perfect candidate for sticking graphene on. Only the structure is the same, because the boron nitride is totally different in terms of conductivity – it’s a very good insulator. The fact that it can be scaled down to any size, only limited by technology, brings boron nitride the merit of being able to carry graphene in the uttermost places, where other technologies couldn’t fit in.
“You want as thin an insulator as possible,” LeRoy added. “The initial idea was to pick something flat but insulating. Because boron nitride essentially has the same structure as graphene, you can peel it into layers in the same way. Therefore, we use a metal as a base, put a thin layer of boron nitride on it and then graphene on top.”