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June 19, 2006

Nanowire Transistors 4 times Faster than Silicon

Researchers at Harvard University have shown that nanowire transistors can be at least four times speedier than conventional silicon devices. The principal researcher, chemistry professor Charles Lieber, says this could lead to inexpensive, high-performance, flexible electronic circuitry for cell phones and displays. It could also save space and further increase speed, he says, by allowing memory, logic, and sensing layers to be assembled on the same chip.

Nanowire transistors may never replace more conventional devices in computer chips used in laptops and personal computers -- the cost of developing large-scale manufacturing would probably not be justified by a 4 to 5 times improvement.

One of the qualities that distinguishes this current work from earlier nanoscale electronics research, including his own, Lieber says, is that the measurements used are industry standards, which makes it possible to compare how nanowires would perform in real devices.

The key to the improved performance is a "core-shell" structure of the nanowires, which confines electrons, or their counterparts, electron holes, in a small space. That allows electrons to zip through the wires quickly, which is key to the speed improvements. In a recent paper in the journal Nature, Lieber made nanowires with a germanium center surrounded by a thin coating of crystalline silicon. And in work described in Nano Letters, the researchers showed the versatility of nanowires by using gallium nitride, which could be useful for high-power, high-temperature applications.

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