PHYSICS NEWS UPDATE
The American Institute of Physics Bulletin of Physics News
Number 371 May 13, 1998 by Phillip F. Schewe and Ben Stein
A CARBON NANOTUBE TRANSISTOR, an electronic device based on a single
rolled-up sheet of carbon atoms, has been built by researchers in the
Netherlands (Cees Dekker, Delft Institute of Technology,
dekker@qt.tn.tudelft.nl), providing a demonstration of room-temperature,
carbon-based electronics at the single-molecule scale. In the device,
a semiconducting carbon nanotube (only about 1 nm in diameter) bridges two
closely separated metal electrodes (400 nm apart) atop a silicon surface
coated with silicon dioxide. Applying an electric field to the silicon
(via a gate electrode) turns on and off the flow of current across the
nanotube, by controlling the movement of charge carriers onto it.
Although carbon nanotubes are robust and durable molecules, they can't yet be
made uniformly. While this can provide disadvantages (a slight deviation
from the desired radius can give the nanotube metallic properties), it can
also bring about advantages--such as the possibility of a metal-semiconductor
junction made completely of carbon nanotubes. (S.J. Tans et al., Nature,
7 May 1998; image at www.aip.org/physnews/graphics)
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