- 11 April 2005 -

InP and InGaAs transistor breaks 600GHz

Reportedly using second-hand Intel equipment, Milton Feng, the Holonyak professor of Electrical and Computer Engineering and a researcher at the Coordinated Science Laboratory at Illinois and his researchers at the University
of Illinois Urbana-Champaign have made yet another record breaking device.

This time the indium phosphide and indium gallium arsenide transistor demonstrated a speed of 604GHz - the fastest transistor operation to date.

In January 2003, Feng’s group of Walid Hafez and Jie-Wei Laihad fabricated a transistor with150nm collector top frequency of 382GHz. In May, it reported a 452GHz device with 25nm base and 100nm collector. More scaling, and reduced collector size cranked up to 75nm for a 509GHz device in November 2003.

Now Feng and his doctoral student Walid Hafez have published a description of their transisto rwinner in Applied Physics Letters. The work was funded by a $5.9m Defense Advanced Research Projects Agency contract.

Hafez reckons that it takes 500 individual steps and two weeks to get the fragile transistor. Sometimes Murphy's Law gets in the way of Moore's Law and he is quoted as commenting "You can sneeze and break it in half. It's like losing a baby."

Feng hopes to achieve his long term goal of the THz transistor next year. Building the 600GHz processor required special geometry - with 13 layers of metal and indium phosphide. Pseudomorphic grading of the material structure allow ed lowering the bandgap in selected areas. This permits faster electron flow in the collector. The compositional grading of the transistor components also improves current density and signal charging time.

The university has applied for a patent on the InP and InGaAs semiconductor chip which is, said Feng, "an extension of transistor technology."