Breaking Moore’s Law: Graphene Nanoribbons

^Ask a technician or a computer science major, and they will likely tell you that the next great leap in computing will only come once Moore’s Law is overcome. This law, which states that the number of transistors on a single chip doubles every 18 months to two years, is proceeding towards a bottleneck. For decades, CPUs and computer chips have been getting smaller, but they are fast approaching their physical limitations.

One of the central problems arising from the Moore’s Law bottleneck has to do with the materials we used to create microchips. Short of continued miniaturization, there is simply no way to keep placing more and more components on a microchip. And copper wires can only be miniaturized so much before they lose the ability to conduct electricity effectively.

graphene_ribbons1This has led scientists and engineers to propose that new materials be used, and graphene appears to be the current favorite. And researchers at the University of California at Berkeley are busy working on a form of so-called nanoribbon graphene that could increase the density of transistors on a computer chip by as much as 10,000 times.

Graphene, for those who don’t know, is a miracle material that is basically a sheet of carbon only one layer of atoms thick. This two-dimensional physical configuration gives it some incredible properties, like extreme electrical conductivity at room temperature. Researchers have been working on producing high quality sheets of the material, but nanoribbons ask more of science than it can currently deliver.

graphene_ribbonsWork on nanoribbons over the past decade has revolved around using lasers to carefully sculpt ribbons 10 or 20 atoms wide from larger sheets of graphene. On the scale of billionths of an inch, that calls for incredible precision. If the makers are even a few carbon atoms off, it can completely alter the properties of the ribbon, preventing it from working as a semiconductor at room temperature.

Alas, Berkeley chemist Felix Fischer thinks he might have found a solution. Rather than carving ribbons out of larger sheets like a sculptor, Fischer has begun creating nanoribbons from carbon atoms using a chemical process. Basically, he’s working on a new way to produce graphene that happens to already be in the right configuration for nanoribbons.

graphene-solarHe begins by synthesizing rings of carbon atoms similar in structure to benzene, then heats the molecules to encourage them to form a long chain. A second heating step strips away most of the hydrogen atoms, freeing up the carbon to form bonds in a honeycomb-like graphene structure. This process allows Fischer and his colleagues to control where each atom of carbon goes in the final nanoribbon.

On the scale Fischer is making them, graphene nanoribbons could be capable of transporting electrons thousands of times faster than a traditional copper conductor. They could also be packed very close together since a single ribbon is 1/10,000th the thickness of a human hair. Thus, if the process is perfected and scaled up, everything from CPUs to storage technology could be much faster and smaller.


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