Today's microprocessors are all made using the CMOS logic family.
It has the advantage of using a minimum amount of electricity, since - exce pt for leakage currents, which are becoming more important as transistors a nd wires shrink - electrical power is only used during changes of state.
However, the performance of CMOS circuits is limited by the slower P-type F ET branch of them - this can be helped by going to Germanium, which has hig h hole mobility, or by using stretched silicon, or by using domino logic... the IBM CELL processor used an alternative approach instead of domino logi c which also worked.
And the fastest logic family used to be ECL, because the transistors didn't saturate. But it was an energy hog.
Silicon carbide can tolerate high temperatures, and it's a semiconductor. T he trouble is that silicon carbide crystals are riddled with defects, so it 's a challenge to even make decent single transistors out of it, let alone microprocessors with millions of transistors!
However, the thought occurred to me that surely there must be some material that forms nice single crystals, free of defects, with the same interatomi c lattice spacing as silicon carbide. One could use wafers of _that_ - pres uming it's also an insulator - and using chemical vapor deposition, produce good silicon carbide transistors in large numbers per die...
No doubt there are good reasons why that is harder than it seems.
John Savard