SiGe transistor hits 800GHz

SiGe record at IHPSilicon germanium has been demonstrated at 798GHz fmax, exceeding the previous speed record for SiGe chips by around 200GHz, according to Georgia Tech, which was testing a transistor made by German lab IHP.

This operating speed was achieved at 4.3K, but record speeds at room temperature look close, said Georgia professor John Cressler.

“The transistor we tested was a conservative design, and the results indicate that there is significant potential to achieve similar speeds at room temperature,” said Cressler. “I believe that these results indicate that achieving terahertz speeds in a robust and manufacturable SiGe transistor is within reach.”

At room temperature, 417GHz was achieved. “At that speed, it’s already faster than 98% of all the transistors available right now,” said Cressler.

IHP, which is a German government funded research centre in Frankfurt an der Oder (the other Frankfurt), designed a SiGe heterojunction within a silicon bipolar transistor and fabricated it on its own 130nm BiCMOS process – which the lab offers in its multi-project wafer foundry service.

Breakdown voltage is 1.7V.

“The results show the potential for Si-based technologies in areas in which compound semiconductor technologies are dominant today,” said Bernd Tillack, who leads the technology department at IHP.

Cressler sees even this transistor as a potential commercial replacement for InP and GaAs in outer space, where temperatures can be extremely low.

The research was published in IEEE Electron Device Letters, February 2014.

Photo: High-speed SiGe chips in a cryogenic probe station at the Georgia Institute of Technology.

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