Germanium Can Take Transistors Where Silicon Can’t

Nearly 70 years ago, two physicists at Bell Telephone Laboratories—John Bardeen and Walter Brattain—pressed two thin gold contacts into a slab of germanium and made a third contact on the bottom of the slab. The flow of current through this configuration could be used to turn a small signal into a larger one. The result was the first transistor—the amplifier and switch that was, arguably, the greatest invention of the 20th century. Thanks to Moore’s Law, the transistor has delivered computers far beyond anything thought possible in the 1950s.

Despite germanium’s starring role in the transistor’s early history, it was soon supplanted by silicon. But now, remarkably, the material is poised for a comeback. The world’s leading-edge chipmakers are contemplating a change to the component at the very heart of the transistor—the current-carrying channel. The idea is to replace the silicon there with a material that can move current at greater rates. Building transistors with such channels could help engineers continue to make faster and more energy-efficient circuits, which would mean better computers, smartphones, and countless other gadgets for years to come.

For a long time, the excitement over alternative channels revolved around III-V materials, such as gallium arsenide, which are made from atoms that lie in the columns just to the left and right of silicon in the periodic table of elements. I was active in that research. In fact, eight years ago, I wrote a feature for this magazine heralding the progress that had been made in constructing transistors with III-V channels.

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