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Why is SiC a good thing? 1. It has a higher bandgap energy than silicon, which means it can tolerate more heat without breaking down. It also means the junctio
by dreamcompiler 5y ago
Why is SiC a good thing?
1. It has a higher bandgap energy than silicon, which means it can tolerate more heat without breaking down. It also means the junctions can be physically smaller.
2. Smaller junctions mean the transistors can switch faster, which means less time spent in the linear region, which means they generate less waste heat than silicon transistors.
3. SiC also has lower ON resistance, which means less waste heat still.
4. SiC conducts heat better than silicon, so removing its [lesser] waste heat is easier and requires a smaller heat sink apparatus.
All of this makes SiC a fantastic technology for power electronics. (It's less important for signal electronics, but even signal electronics waste small amounts of power so reducing that further is still relevant.)
For EVs, SiC inverters mean less mass for an EV to carry around. Less mass per se doesn't matter as much as you might think for an EV because with regenerative braking you get back some of your acceleration energy when you decelerate. However, air resistance matters enormously in an EV because you can't get back the energy you lost pushing the car through the air. And "less mass" also means "smaller" and "smaller" means "more opportunities to make the car aerodynamically efficient."
- sonium 5y agoThank you for answering everything I ever wondered about SiC. Are there any other semiconductors that would be even better than SiC in all four points?
- dreamcompiler 5y agoDiamond is even better in terms of bandgap and thermal conductivity (one way jewelers verify a diamond is real is by checking to see if the gem has ridiculously high thermal conductivity). But diamond semiconductors are much too expensive ATM. Gallium Nitride is the closest competitor to SiC now; it's better than SiC for high frequency applications but worse for high temperature applications and GaN is somewhat harder to manufacture. But that's changing rapidly. https://www.arrow.com/en/research-and-events/articles/silicon-carbide-and-gallium-nitride-compared https://www.arrow.com/en/research-and-events/articles/silico...
- jpmattia 5y ago> But diamond semiconductors are much too expensive ATM. It is also difficult to dope diamond n-type, as most of the donors are not shallow. Interestingly: The conduction band in bulk diamond is above the vacuum level, meaning that conduction electrons "want" to fall out of the material. (Surface physics gets in the way.)