A single-electron transistor carved entirely in a graphene sheet. The central element is a so-called quantum dot, which allows electrons to flow one by one. The dot is connected to wider regions that have contact pads used to turn the transistor on and off. Credit: Leonid Ponomarenko

Researchers at the University of Manchester in England have made a single-­electron transistor using graphene, a sheet of graphite only one atom thick. Andre Geim, the professor of physics who led the work, says the transistor consists of electrical contacts that supply and collect current through three-­nanometer-wide areas containing a central island of graphene, called a quantum dot. When current is applied, an electron jumps from one contact to the quantum dot and then to the other contact. A problem with previous single-­electron transistors, says Geim, is that quantum dots of other materials, when shrunk this much, act "like a droplet of liquid on a hot plate" at room temperature. Graphene quantum dots, however, are stable. The Manchester research could yield a practical technology if fabrication techniques advance enough to produce such small features.

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