- 25 March 2006 -

IBM researchers test nanotubes

IBM researchers have fabricated a 'test bed' circuit for assessing the performance of carbon nanotubes.

The results of the paper, "Integrated Logic Circuit Assembled on a Single Carbon Nanotube" are to be published in the current issue of Science.

Prior to this it has been difficult to evaluate carbon nanotube parameters which are thought to have an electric current density exceeding that of copper. Now, says Joerg Appenzeller, staff manager for IBM Research, IBM has created a ring oscillator test circuit. This is being used to evaluate the performance of new materials and semiconductor manufacturing techniques, out of a combination of the CMOS circuitry used by the majority of chips and a single carbon nanotube.

They have discovered that the test material yields a speed of 52 MHz. Not impressive for silicon but a baseline to discover if future improvements can push the performance into the gigahertz range. "Ultimately, it will be much faster than it is now," said Joerg Appenzeller, an IBM Research staff manager.

It will also provide the means to test another key hypothesis that nanotubes and CMOS silicon can be manufactured together. While the current design appears to bear that out to some extent, future work will need to be done to actually align the nanotubes.

Previously, Using carbon nanotubes, IBM researchers built the smallest computer logic circuit ever created: a two-transistor "NOT gate" the size of a single carbon molecule. IBM's Phaedon Avouris, manager of nanoscale science at IBM Research, saw the achievement as the next big step in the replacement of today's silicon-based computer chips and the preservation of Moore's Law.

Web: http://www.research.ibm.com/nanoscience