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You need to use nuclear-powered transistors!

No, I'm not joking. For these kinds of voltages, you need to use highly homogenous doped silicon, and the only way to produce it is to irradiate silicon with neutrons. It transmutes some of the silicon atoms into phosphorus: https://nrl.mit.edu/facilities/ntds/

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I assume that if people are going to the trouble to literally irradiate the material in order to get what they need, they can't get the results by just mixing in phosphorus. Could somebody who actually understands this tell me why that is?

Because there is no other way to produce homogenous enough thick wafers of doped silicon. Other methods rely on diffusion from the surface, which is not enough for this case.

And doping during crystal growth doesn't produce homogenous enough silicon.

https://www.waferworld.com/post/the-complete-guide-to-doping...

It's apparently possible for boron doping.

I think because phosphorus is bigger than silicium you'll get too many defects in the crystal, while with the smaller boron it is not an issue.

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