GE develops diode built from carbon nanotubes

Scientists at GE Global Research have developed a device which many semiconductor researchers think will replace conventional...

Scientists at GE Global Research have developed one of the most fundamental devices within an electronic circuit using carbon nanotubes, which many semiconductor researchers think will replace conventional silicon building blocks in the future.

Researchers used a carbon nanotube to create a diode, said Ji-Ung Lee, a senior scientist with GE Global Research, a division of General Electric. A diode is a basic semiconductor device used to channel electricity in a specified direction.

Electrical circuits are made with several basic parts, such as transistors and diodes. Researchers at other organisations have demonstrated preliminary transistors and diodes built from carbon nanotubes, but GE's device performs about as well as a conventional silicon diode, unlike earlier efforts, Lee said.

Chip designers have been able to increase performance and decrease transistor size for years using CMOS (complementary metal-oxide semiconductor) silicon technology, but are starting to run into problems stemming from current leakage. The dimensions of modern semiconductors are growing so small that electrons can leak through the structures on a chip and escape as heat.

Carbon nanotubes are under intense scrutiny as a possible successor to silicon technology over the next decade or so. A carbon nanotube is simply a cylinder made from carbon atoms that is about 10,000 times thinner than a human hair.

The nanotubes are strong and exhibit many thermal and electrical properties desirable to chip makers. However, most of their development has taken place under laboratory conditions, and it is unclear right now how carbon nanotubes will be manufactured in the volumes required by the modern semiconductor industry.

The carbon nanotube diode developed by GE Global Research can emit and detect light, Lee said. This is an important property for developers of optoelectronic devices that use light instead of electricity to transmit information, he said.

Sensors are another possible application for the carbon nanotube diode, Lee said. Intel and the Massachusetts Institute of Technology in Cambridge are studying possible uses for a large-scale deployment of sensor networks, such as chemical detection or home monitoring.

A great deal of work remains to identify the best applications for the carbon nanotube diode, Lee said. GE must also improve the manufacturing processes that were used to build the diode so that larger yields are generated, he said.

Tom Krazit writes for IDG News Service

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