Nanotubes boost molecular devices

Researchers from Stanford University have constructed an extremely small transistor from a pair of single-walled carbon nanotubes and organic molecules. A single-walled carbon nanotubes is a rolled-up sheet of carbon atoms.

The transistor is two nanometers wide and regulates electric current through a channel that is just one to three nanometers long. Today's computer chips sport millions of transistors that have 90-nanometer channels. A nanometer is one millionth of a millimeter, or the span of 10 hydrogen atoms. The researchers' transistor is about 40,000 times narrower than a human hair.

The tiny transistor could eventually be used in ultra-low-power electronics. Transistors made from organic molecules are currently slower than today's transistors made from silicon, but are cheap and easy to work with. Scaling organic electronic devices down to the molecular level using nanotube electrodes should significantly boost organic electronics' performance, according to the researchers.

The researchers cut metallic nanotubes to form electrodes, then deposited one of two organic materials to form a semiconducting channel between the electrodes.

The researchers compared their nanotubes-electrode organic transistor to an organic transistor made with larger metal electrodes. The nanotube device had a large enough difference between on and off voltages to work as a practical transistor, while the larger device did not.

The tiny transistor could be used in practical applications in two to five years, according to the researchers. The work appeared in the August 23, 2004 issue of the Journal of the American Chemical Society (JACS).