The Novel Material That's Shrinking Phone Chargers, Powering Up Electric Cars, and Making 5G Possib
Present in most LED screens, as well as the LED lights that now provide much indoor illumination, is the metal gallium. And while not as well known as silicon, it is taking over in many of the places that silicon once reigned supreme—from antennas to charging bricks and other energy-converting systems known as “power electronics.” In the process, it’s enabling a surprising array of new technologies, from faster-charging cellphones, to lighter electric vehicles, to more power-efficient data centers that run the services and apps we use.
A byproduct of extracting aluminum from rock, gallium has such a low melting temperature that it turns into a runny, silvery-white liquid when you hold it in your hand. On its own, it isn’t terribly useful. Combine it with nitrogen, to make gallium nitride, and it becomes a hard crystal with valuable properties. It shows up in laser sensors used in many self-driving cars, antennas that enable today’s fast cellular wireless networks, and, increasingly, in electronics critical to making renewable-energy harvesting more efficient. Many of the most tangible things made possible by gallium nitride, also known as GaN, are happening in power electronics. Today, you can buy small USB-C chargers with enough juice to power your laptop, phone and tablet simultaneously, even though they are no bigger than the much less powerful versions that have for years come with our gadgets.
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Miracle material that GaN may be, it faces competition from tried and true silicon and a growing list of new materials that show potential to revolutionize our electronics. Still, its uses are expanding. GaN Systems also has customers testing its chips in data centers, where reducing power consumption and waste heat can translate into massive savings on electric bills. None of its data-center customers have publicly acknowledged using the technology. There was a time, not so long ago, that GaN was a mere laboratory curiosity. Then the Pentagon got interested, hunting for new kinds of electronics to drive next-generation radars and wireless communications. Beginning around 2000, funding from Darpa, the Defense Department’s advanced research agency, drove the experimentation required to overcome many of the hurdles to its commercialization, says Rachel Oliver, a professor of materials science and director of the Centre for Gallium Nitride at Cambridge University.
Alongside its myriad applications in the civilian world, GaN now shows up in military hardware used for everything from radio jamming to missile defense, all made possible by its unique properties. In contrast to silicon, GaN can handle relatively large amounts of electricity. It has the unusual property of being both very good at moving electrons about and very good at not allowing them to go where you wouldn’t want them to be, which makes it both useful and relatively safe, says Dr. Oliver. Along with its talent for conducting electricity, it’s GaN’s ability to operate at frequencies that are much higher than possible with silicon—between 30 and 500 times as fast in commercial applications—that enable chargers that are much smaller or deliver more power than traditional ones.
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That said, GaN chips aren’t a slam-dunk winner. Advances in materials science have generated a handful of competitors. Traditional silicon power electronics are still dominant in most applications, and in the automotive world, silicon carbide, an alternative with many of the same properties as GaN, has a much longer track record, says Gartner’s Mr. Brocklehurst. An array of promising but less well-understood substances could give all of the previously mentioned ones a run for their money, including gallium oxide and aluminum oxide. Both are semiconductors that can be patterned into microchips, says Dr. Oliver. So far, GaN can’t handle the electric-current flows needed to run the kind of computations carried out by traditional silicon logic chips. But recent findings suggest that may be changing.
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