To address the energy wastage issue in the intrinsically inefficient power conversion in electronics, scientists have proposed a new design.
Power electronics currently rule our every day lives. They are everywhere – devices we use to charge our portable devices; in battery packs of electric cars; and they’re in the power grid itself, where they mediate between high-voltage transmission lines and the lower voltages of household electrical sockets. Inefficiency of power converters is being looked into and power converters made from gallium nitride have begun to reach the market, boasting higher efficiencies and smaller sizes than conventional, silicon-based power converters.
However, these gallium nitride power devices aren’t able to handle voltages above about 600 volts. That will likely change thanks to a new study by an international team of scientists wherein they have presented a new design that, in tests, enabled gallium nitride power devices to handle voltages of 1,200 volts.
Power electronics depend on transistors, devices in which a charge applied to a “gate” switches a semiconductor material — such as silicon or gallium nitride — between a conductive and a nonconductive state.
For that switching to be efficient, the current flowing through the semiconductor needs to be confined to a relatively small area, where the gate’s electric field can exert an influence on it. In the past, researchers had attempted to build vertical transistors by embedding physical barriers in the gallium nitride to direct current into a channel beneath the gate.
But the barriers are built from a temperamental material that’s costly and difficult to produce, and integrating it with the surrounding gallium nitride in a way that doesn’t disrupt the transistor’s electronic properties has also proven challenging.
Researchers adopt a simple but effective alternative. Rather than using an internal barrier to route current into a narrow region of a larger device, they simply use a narrower device. Their vertical gallium nitride transistors have bladelike protrusions on top, known as “fins.” On both sides of each fin are electrical contacts that together act as a gate. Current enters the transistor through another contact, on top of the fin, and exits through the bottom of the device. The narrowness of the fin ensures that the gate electrode will be able to switch the transistor on and off.