With each new generation of microchips, transistors are being placed closer and closer together. This can only go on so long before there’s no more room to improve, or something revolutionary has to come along to change everything. One of the materials that might be the basis of that revolution is none other than graphene. Researchers at the University of California at Berkeley are hot on the trail of 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 has already earned its discoverers a Nobel Prize, but its true promise is only beginning to be realized. Graphene is 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.
Work 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 probably sounds incredibly precise. However, even a few carbon atoms can — one way or the other – completely alter the properties of the ribbon, preventing it from working as a semiconductor at room temperature.
Berkeley chemist Felix Fischer thinks he might have the solution. Rather than carve ribbons out of larger sheets like some sort of demented microscopic tailor, Fischer is creating the nanoribbons fully formed 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.
Fischer begins by synthesizing rings of carbon atoms similar in structure to benzene. Heating these molecules under the right conditions encourages them to bind together in 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 structure — graphene. 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 metallic conductor. Transistors based on nanoribbons could also be packed very close together — a human hair is 10,000 times wider than Fischer’s nanoribbons. Thus, a chip based on graphene nanoribbons could have a huge number of very fast transistors that dissipate heat more efficiently than metal.
If the process is perfected and scaled up, graphene nanoribbons could allow all electronic circuits to be improved dramatically. Everything from CPUs to storage technology could get faster, and Moore’s Law might have a future after all.
