IBM tries to tackle nanotube chip cooling

02.03.2009
IBM researchers on Monday said they are looking at ways to improve heat management in carbon nanotube transistors to prevent them from self-destructing.

The researchers have found ways to measure the temperatures of tiny carbon nanotubes, which was not previously possible, said Phaedon Avouris, IBM fellow and manager, nanoscale science and technology, at IBM Research.

Today's laptops and desktops use silicon chips that are being scaled down to smaller sizes to make them faster and more power efficient. To that end, more transistors are being bundled into chips, and the smaller a transistor, the better it performs. To create smaller transistors, chip developers are exploring the use of carbon nanotubes. Carbon nanotubes are cylinders made out of carbon atoms, with a diameter of 1 to 2 nanometers.

But carbon nanotubes need to be understood before being implemented, and heat dissipation is one of their limitations, Avouris said. Too many carbon nanotubes bunched together are difficult to cool by just blowing air through the circuits, he said. Excess heat lowers performance and eventually could cause the nanotubes to self-destruct.

"The first step is we want to understand how electrons flow through this material, as it is completely different from the way electrons flow through silicon," Avouris said. Carbon nanotubes based on materials such as graphene have unusual heating and dissipation mechanisms that could have wider implications for nanotechnology.

Heat is generated in carbon nanotubes by how quickly atoms vibrate. The faster the atoms vibrate, the more heat they generate, which is then dissipated to the substrate, which is the material that holds the nanotube in place. The scientists likened understanding the heating and dissipation of nanotubes to understanding heat dissipation in conventional silicon chips.