Gallium nitride device can handle high voltages and make power conversion more efficient. (Image credit: MIT)


Most people know that electrical efficiency affects nearly everything that uses power- smartphones/mobile devices, electric vehicles and even the grid. Power converters play a significant role in the electrical equation, but they are incredibly inefficient and will never output more than the power it takes in. They are responsible for modifying voltages or convert between DC and AC like in high-voltage transmission lines and lower voltage home electrical outlets.


MIT has recently announced they have designed a new device that makes those power converters more efficient with the help of gallium nitride. Usually, gallium nitride-based semiconductor power conversion devices can’t handle anything above 600 volts, enough for some household electronics but not much else. MIT’s new semiconductor device however, can control twice the amount of voltage (1,200-volts), enough capacity to use in electric vehicles and believe they can increase the voltage to 3,500 to 5,000-volts to power electronics on the grid itself.


The secret lies in their new gallium nitride design. Today’s power converter devices are manufactured laterally on top of gallium nitride wafers, which limits how much voltage they can handle. MIT’s device, on the other hand, is constructed vertically, allowing for more electrical flow with minimal loss. MIT professor Tomas Palacios states, “These are devices where the current, instead of flowing through the surface of the semiconductor, flows through the wafer, across the semiconductor. Vertical devices are much better in terms of how much voltage they can manage and how much current they control.”


Vertical gallium nitride resistors with fins that act as gates, switching the transistor on and off. (Image credit: MIT)


When it comes to lateral devices, all the current flows through a narrow slab close to the semiconductor’s surface, limiting them from gaining increased voltage while vertical devices utilize the entire surface of the semiconductor, gaining significantly increased voltage prowess. That being said, power electronics depend on transistors to function efficiently as well, but manufacturing vertical-based power devices are both costly and challenging to produce and integrating them into the gallium nitride that doesn’t interfere with the transistors electronic properties are difficult.


The researchers developed an alternative process that makes it easier and less costly to produce vertical power devices- instead of using a narrow region to route power on a large device; they just use a narrower device. The team developed vertical gallium nitride transistors with fins that feature contacts on both sides that when bridged act as a gate and by confining electrical current to a narrower area, it becomes more efficient with less power bleed. 


There’s no word on when these new power converters will be available for the grid or electric vehicles and more than likely; the team will continue developing their latest technology to hit higher levels of conversion efficiency. Then again, you could always jump in your Land Speeder and pick some up at Tosche Station on Tatooine if need be.


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