Silicon carbide is the senior of WBGs and has been in development as a transistor material for decades. During that time, engineers have started using younger WBG budding materials, such as gallium nitride or GaN. In the 1980s, researchers used gallium nitride to create the world’s first bright blue LEDs. Blue light consists of high-energy photons; gallium nitride, with its wide bandgap, was the first semiconductor that could practically produce photons with sufficient energy. In 2014, three scientists were awarded the Nobel Prize in Physics for that innovation, which became ubiquitous in devices such as TV screens and light bulbs.
Recently, researchers have started using gallium nitride to improve power electronics. The material has achieved commercial boom in recent years in adapters for charging phones and computers. These adapters are smaller, lighter, faster charging and more efficient than traditional adapters that use silicon transistors.
“A typical charger you buy for your computer is 90 percent efficient,” said Jim Witham, chief executive of GaN Systems, a Canadian company that supplied the transistors in Apple’s gallium nitride laptop chargers released last fall. “Gallium nitride is 98 percent efficient. You can reduce power losses four times.”
Yole Développement estimates that the gallium nitride market will grow to $2 billion by 2027, from a total of about $200 million this year.
Wide-bandgap materials are also finding their way into other applications. Data centers, large facilities filled with computer servers that run the online services we all depend on, are notorious users of electricity. Compuware, a supplier of high-performance power supplies for data centers, says its gallium nitride-based power supplies reduce wasted electricity by about 25 percent and take up 20 percent less space than conventional appliances, giving customers more servers in the same rack. The company also says its gallium nitride power supplies are used in major corporate data centers around the world.
Engineers are also working on using WBG materials to better take advantage of renewable energy sources. Solar cells and wind turbines rely on traction inverters to feed electricity into a home or grid, and many companies expect gallium nitride to do that job better than silicon. Enphase, a supplier of inverters for solar installations, is currently testing gallium nitride-based inverters to ensure they can withstand harsh weather conditions on roofs for decades. In one test, Enphase submerges inverters in a pressure cooker, places the pressure cooker in a sealed chamber, and the temperature fluctuates between 185 degrees and minus 40 degrees Fahrenheit over the course of 21 days. If gallium nitride devices survive the challenges, Enphase co-founder Raghu Belur plans to quickly switch to the new material. “It’s definitely going that way,” he said.
At an investor meeting last year, a senior Enphase engineer gave a more compelling forecast, saying, “It’s the end of the road for silicon.”