Comment Re:everything old is new again? (Score 2) 90
GaAs and GaN have some real advantages over silicon, but price and density has not been their strong suit. Silicon is cheap per unit of area, and is compatible with copper metallization. GaAs in particular has always been sensitive to copper contamination, hence the use of gold for most of the interconnects. GaN has very fast switching speeds while handling an order of magnitude more voltage than GaAs (~10x the breakdown for the same Ft). So for a ~100 GHz Ft silicon can handle just a volt or so (think 65 nm nodes and smaller to get those speeds), GaAs can handle about ~5V, and GaN is more like 40V.
The real story here is the ability to run GaN with existing silicon equipment with silicon type costs, rather than the relatively low density fab equipment GaAs and GaN are usually processed on (usually the repurposed cast-offs from old silicon fabs).
GaN by its nature operates at high voltages, like 15V minimum, so don't expect a GaN based processor any time in the near future. Instead it sounds like they are claiming a 100x improvement in the Ron*Coff figure of merit for power switching devices. The payoff would be smaller and more efficient power electronics, such as the mentioned laptop supply brick, electric car power electronics, etc. Don't expect this has any bearing on the plateau of Moore's Law.