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Researchers create transistor with carbon nanotube, molecule

Posted: 24 Jan 2006     Print Version  Bookmark and Share

Keywords:R. Colin Johnson  Columbia University  organic molecule  carbon-nanotube  molecular transistor 

Columbia University researchers have successfully married a carbon nanotube with an organic molecule, creating what they said is the world's first hybrid carbon-nanotube/molecular transistor.

The experimental device enabled the chemical reaction in an application-specific organic molecule to be harnessed by the high carrier-mobility of carbon nanotubes.

"We have achieved something of a milestone by being able to wire up an ultra small transistor where we married carbon nanotubes with organic molecules," said Shalom Wind, senior research scientist at Columbia University. "We are taking the best properties of both and optimizing them so that we can combine them into a single switch."

Wind joined Columbia in 2003 after a stint at IBM Research's T.J. Watson Research Centre where he helped characterise nanotube transistors. Like IBM's original design, Columbia's molecular transistors used a carbon nanotube as the transistor channel. The researchers cut the nanotube and inserted an application-specific organic molecule to functionalise the resulting molecular transistor, leaving the nanotubes as the source—and drain—electrodes.

"Molecular transistors represent the ultimate in scaling, so we need to understand them," Wind said. "We grew our nanotubes in place on the substrate, made a gap and inserted the organic molecules, which have their own special properties, enabling them to be used, for instance, as sensors."

The researchers successfully inserted several different types of organic molecules, and reported detailed test results for an application-specific organic molecule that changed its conductivity in response to pH. This enabled the molecular transistor to act as a pH sensor.

The insertion technique used nanoscale lithography and an oxidation process that prepared the severed ends of the nanotube for chemical bonding to the inserted molecule. By ensuring the gap cut in the nanotube was similar in size to the molecule to be inserted, the researchers were able to marry the ends of the nanotube to a single organic molecule.

The researcher was performed at Columbia University's Nanoscience Centre.

- R. Colin Johnson
EE Times

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