Graphene, an atom-thick carbon sheet, is a promising replacement for silicon in electronic circuits, since it transports electrons much faster. IBM researchers have already made transistors, the building blocks of electronic circuits, with graphene that work 10 times faster than their silicon counterparts. But to make these transistors, researchers first have to alter the graphene's electronic properties by cutting it into thin ribbons, which are then incorporated into devices. Researchers have made these nanoribbons with lithography, with chemical solution-based processes, or by unzipping carbon nanotubes.
In the new Science paper, researchers at the Georgia Institute of Technology and the U.S. Naval Research Laboratory instead "write" such nanoribbons on a surface rather than cutting graphene. The researchers start with a graphene oxide sheet, which doesn't conduct electric current. When they pull an AFM tip heated to between 150 °C and 1060 °C across the sheet, oxygen atoms are shed at the spots that the tip touches. This leaves behind lines of almost-pure graphene that are 10,000 times more conductive than the surrounding graphene oxide.