![]() Solid-state devices based on germanium boomed in the postwar years U.S. That changed during World War II, when germanium’s semiconducting properties-that is, its ability to switch between permitting and blocking the flow of current-were discovered. Named in honor of Winkler’s homeland, the material was long considered a poor conducting metal. Germanium was first isolated and identified by the German chemist Clemens Winkler in the late 19th century. In a few years’ time, we may find that the material that brought us the transistor has helped usher it into a new age of remarkable performance. These developments could be the first steps in an industry trend to adopt the use of higher and higher proportions of germanium in the channel. Transistors that use a combination of silicon and germanium in the channel can reportedly be found in some recent chips, and they made an appearance in a 2015 demonstration of future chip-manufacturing technology by IBM and partners. These include nanowire devices, which may be next in line when the present state-of-the-art transistor design, known as the FinFET, can’t be miniaturized any longer.īest of all, it turns out that putting germanium back into the mix isn’t as big a challenge as it might seem. We have also constructed a range of different transistor architectures using the material. Since then, we’ve demonstrated the first complementary-metal-oxide-semiconductor (CMOS) circuits-the kind of logic inside today’s computers-made with germanium grown on ordinary silicon wafers. So a few years ago, my team at Purdue University, in West Lafayette, Ind., began experimenting with a different kind of device: a transistor with a channel made of germanium. It’s also likely to be too expensive and difficult to integrate with existing silicon technology. Images: Heng Wu/Purdue Universityīut as we eventually discovered, the III-V approach has some fundamental physical limitations. The distance between each fin in the top image is in the tens of nanometers. The two transistors in the FinFET-based inverter contain finlike channels, which stand out from the plane of the wafer (top, one set of fins (in pink) from a bird’s-eye view bottom, an oblique view of another set). ![]() ![]() 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. 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.įor 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. ![]() The idea is to replace the silicon there with a material that can move current at greater rates. The world’s leading-edge chipmakers are contemplating a change to the component at the very heart of the transistor-the current-carrying channel. But now, remarkably, the material is poised for a comeback. Thanks to Moore’s Law, the transistor has delivered computers far beyond anything thought possible in the 1950s.ĭespite germanium’s starring role in the transistor’s early history, it was soon supplanted by silicon. The result was the first transistor-the amplifier and switch that was, arguably, the greatest invention of the 20th century. The flow of current through this configuration could be used to turn a small signal into a larger one. 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.
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