Another advantage occurs to me: (g) Thermal immunity. That is, it seems to me that a device based on these micro-vacuum-tubes, if designed right, could work at any temperature from, say, 0 kelvin to 600 kelvin. It would work on Venus. Meanwhile semiconductors are highly affected by temperature changes because more (or less) dopant atoms are ionized at higher (lower) temperatures. So long as the temperature was well below melting points and metal "work function" levels needed to allow substantial thermionic emission, these devices ought to work in a temperature-independent manner. Old-style vacuum tubes used heated filaments and anodes made of special low-work-function materials. The new idea should not need such materials. I'm fascinated by Tom Knight implying this whole idea was around for a long time but classified secret. The inventors I cited seemed to think it was their own idea, and they worked at NASA. If this is truly a great idea, and it truly was suppressed for decades by secrecy... that seems yet another severe indictment of the whole secrecy system...