Scientists build the world's fastest transistor

A research team at Illinois University smash 600GHz barrier

Steve Malone
13 Apr 2005

Scientists at the University of Illinois have built what they claim is the world's fastest transistor.

The new device has smashed through the 600GHz barrier and switches at a world record 604GHz. The researchers behind the transistor say that a terahertz transistor could now be within reach. The previous record was held by a Japanese team which clocked a device at 560GHz.

Instead of using traditional silicon the new transistor has been created with indium phosphide and indium gallium arsenide. These compounds were combined to create a three-layer material known as a bipolar transistor. A transistor is made up of three components - an emitter, a base and a collector. The Illinois team specially altered the collector's crystalline structure with additional indium to create what is known as a pseudomorphic heterojunction. This allows electrons to move between the two layers much more freely, in effect speeding up the flow of current.

'Pseudomorphic grading of the material structure allows us to lower the bandgap in selected areas,' explained Milton Feng, the Holonyak Professor of Electrical and Computer Engineering at Illinois. 'This permits faster electron flow in the collector. The compositional grading of the transistor components also improves current density and signal charging time.'

As with all cutting edge electronic research, it may be a number of years before we see any results in a commercial product. At the moment the device costs around 100 times as much as an equivalent silicon-based transistor although mass production could drive the cost down by as much as 90 per cent. A potentially more serious barrier to mass adoption might be that the new device is fairly power hungry, which limits the ability to cram the transistors closely together in a microprocessor device.

If the new device does become commercially viable the ultra high switchings speeds are likely to find a home firstly in communications devices. As likely as not this will probably mean military applications before being introduced in high speed routers and switches in the telecoms market.

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