"Faster and faster chips open up new applications and reduce costs for existing products," said Professor David Ahlgren of IBM.

Exotic chips

At the moment, most microchips are made from silicon.

But in recent years, there has been a realisation that silicon cannot match other materials in terms of processing speed.

For applications that require huge amounts of calculations every second, like collision warning systems in cars and trucks, companies use exotic materials to produce the necessary power.

Materials like gallium arsenide are commonly used, but are expensive and difficult to fabricate.

However, the chip industry would like to continue to use proven silicon manufacturing technology that is reliable and cheap.

The new experiments were part of a project to explore the speed limits of devices made of silicon and germanium.

Super cooled

Germanium is already added to the silicon chips used in mobile phones to make them operate more efficiently.

Adding the element allows chips to run faster and use less power. Importantly, they can also be fabricated using existing silicon techniques.

These chips are already known to operate at faster and faster speeds as they are cooled.

To break the speed record, the researchers super-cooled an IBM prototype of a new "high frequency" device to -268.5 degrees Celsius, using liquid helium.

This temperature is just above absolute zero, the theoretical minimum temperature possible. When cooled, the chips were able to perform half a trillion calculations every second, a speed of 500 GHz.

By comparison, a powerful desktop PC is capable of about five billion calculations per second.

"A decade ago we couldn't even envisage being able to run at these speeds," said Professor Ahlgren.

Next generation

At room temperature the chips still managed to outperform standard silicon chips, running at about 350 billion calculations per second.

However, the researchers say they can push the chips even further.

"We observe effects in these devices at cryogenic temperatures which potentially make them faster than simple theory would suggest," said Professor John Cressler of the Georgia Institute of Technology.

The team believe it is possible to make chips run at 1,000 Ghz, or one Terahertz, at room temperature.

"Understanding the basic physics of these advanced transistors arms us with knowledge that could make the next generation of silicon-based integrated circuits even better," said Professor Cressler.