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Putting Germanium in a Vise

Silicon chips with compressed germanium run faster

3 min read

24 February 2005--The old-fashioned way to speed up circuits was to shrink the components, but now that the payoff from that strategy is declining, semiconductor manufacturers are seeking other ways to squeeze out performance--notably by squeezing the semiconductor itself. If you squash or stretch certain semiconducting crystals, they convey electrical charges faster. In a CMOS transistor, the result of such "strain" is faster switching and higher current output, with most of the effect coming in the channel--the connection between the transistor's source and the drain. In the past two years, strained-silicon channels, in which the silicon is stretched, have come into general production. Now scientists at IBM Corp. have demonstrated still greater improvements in channels made of germanium that has been squeezed, or compressively strained.

According to Huiling Shang, a research staff member at the IBM Thomas J. Watson Research Center in Yorktown Heights, N.Y., transistors with strained-silicon channels offer output current just 10 to 30 percent higher than that in unstrained silicon, whereas strained-germanium channels raise it by 200 percent. She notes that although the idea had been kicking around for a few years, it became practical only when IBM discovered a fabrication method compatible with conventional CMOS technology, the linchpin of the electronics industry. The company announced the discovery in December, at the International Electron Devices Meeting, in San Francisco.

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The Transistor at 75

The past, present, and future of the modern world’s most important invention

2 min read
A photo of a birthday cake with 75 written on it.
Lisa Sheehan

Seventy-five years is a long time. It’s so long that most of us don’t remember a time before the transistor, and long enough for many engineers to have devoted entire careers to its use and development. In honor of this most important of technological achievements, this issue’s package of articles explores the transistor’s historical journey and potential future.

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