An Indian origin scientist at the Rensselaer Polytechnic Institute has discovered how graphene's extremely efficient conductive properties can be exploited for use in nanoelectronics, as a possible heir to copper and silicon.
Graphene, a one atom thick sheet of carbon, was made in the laboratory in 2004 with the help of everyday, store-bought clear adhesive tape. Graphite, the common material used in most pencils, is made up of countless layers of graphene. Researchers simply used the gentle stickiness of tape to break apart these layers.
Now Saroj Nayak, an associate professor in Rensselaer's Department of Physics, Applied Physics and Astronomy, and his team, have by running dozens of robust computer simulations, demonstrated for the first time, that the length and the width of graphene directly impacts the material's conduction properties.
The team found in experiments, that in the form of a long 1-D nanoscale ribbon, which looks like molecular chicken wire, graphene demonstrates unique electrical properties that include either metallic or semiconducting behaviour.
When short segments of this ribbon are isolated into tiny zero-dimensional (0-D) segments called 'nanorectangles,' where the width is measured in atoms, they are classified as either 'armchair' or 'zigzag' graphene nanoribbons. Both types of nanorectangles have unique and fascinating properties.
According to Nayak, a physical science PhD graduate from Jawaharlal Nehru University, Delhi, their research is an important first step for developing a way to mass produce metallic graphene that could one day replace copper as the primary interconnect material on nearly all computer chips.
Also unlike carbon nanotubes, which are essentially made of rolled-up graphene, and are another potential heir to replace copper as the primary material used for interconnects, graphene can be produced in a more controlled way.
When single-walled carbon nanotubes are synthesised, about one-third of the batch is metallic and the remaining two-thirds are semiconductors. As such, it becomes extremely difficult to separate the two on a mass scale, said Nayak.
The study, 'Energy gaps in zero-dimensional graphene nanoribbons' appears in the July 23 issue of Applied Physics Letters.
