Why GaN?

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A high power switch has to handle several things very well. First, it has to be able to switch fast. If the switch is fast, then all the reactive components can be cheaper and smaller -- which is highly desirable. Then, it should not waste a lot of heat in doing the switching work. This is not only because of the wastage of energy, but the wasted energy essentially is dissipated as heat and increases the temperature of the chip. If the chip is hotter, then it lasts for a shorter time -- and nobody wants that. For that purpose, it is also desirable to have high thermal conductivity so that any dissipated heat can be removed easily.

Then, a lot of present day applications need a very high voltage. And when the switch is turned off, even at high voltages like 1200V, the switch should totally prevent any flow of current. And while doing all these, the price of the switch should be low so that it can find application in more and more areas.

Present day power switches are made of Silicon and Silicon Carbide. Silicon just can't handle the high voltage because of the fundamental limitation due to its smaller band-gap. SiC on the other hand, is very expensive. And because it is difficult to make a good heterojunction, GaN switches easily beat them in speed.

So, there you go -- GaN can switch faster than anything else, it can block enormous voltages when turned off, and works efficiently without wasting heat. We just need to take this technology forward to commercial reality.