University of Manchester New results keep coming fast and furious from graphene, the single-atom-thick form of graphite. Resembling chicken wire in structure, graphene has captured researchers' attention over the past few years for its combination of exotic physics, attractive electronic properties and ease of preparation (see my slideshow on how to make your own graphene"with Scotch tape). Recently, my colleague Steve Ashley alerted you to a Nature Nanotechnology report on just how well graphene conducts electricity. By one measure, it has more conductivity than any other material at room temperature. (A second study reported similar results.) But it'll need more than that to usurp silicon as the stuff of integrated circuits, as commenters pointed out. This week we find that the same group from the University of Manchester has built excruciatingly tiny, transistor-like devices by carving graphene into objects called quantum dots. Etching graphene into quantum dots or narrow strips allows researchers to work around the fact that its conductivity does not normally switch off"an essential prerequisite for making a transistor. In prior work, the Manchester group demonstrated that they could produce a 100-nanometer-wide quantum dot capable of stopping and starting individual electrons. (A nanometer is one billionth of a meter.) Publishing in Science, the researchers extended the single-electron transistor concept to even tinier dots, as small as a single nanometer, or about one atom by 10 atoms in area. That could be an advance, because silicon starts to go haywire when it gets thinner than 10 nanometers, which limits the density of conventional transistors that could be packed onto a computer processor. So researchers are exploring different approaches to see if they can keep Moore's Law chugging. The press release bills the result as the world's smallest transistor, which seems arguable: Claims of single-electron transistors go back to at least to at least this 1997 Nature paper, although maybe graphene's thinness makes this transistor the smallest ever. Either way, the process of making these graphene dots is still trial and error, which is a big hurdle. But on the plus side, now researchers know at least that graphene keeps working at sizes small enough for the computers of tomorrow.


 

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