At the turn of the 60s and 70s, vacuum electronic tubes were completely replaced by semiconductor transistors. However, their "funeral" was premature. Today we can safely talk about the creation of nanovacuum channel transistors - NVCT, which have absorbed all the best from their predecessors.
Compared to conventional transistors, NVCTs are much faster. They are more resistant to high temperatures and radiation, which makes them indispensable for use in technology for future space missions and in THz electronics. They will also be able to "amend" the well-known Moore's Law, according to which the number of transistors in a computer chip cannot be limitless.
As you know, vacuum tubes were quite bulky and consumed a huge amount of energy. NVCT-transistors in this sense are "unpretentious" and can take only a few nanometers, so they can be seen only with a scanning electron microscope.
It looks like the power consumption issue has been resolved. Scientists at NASA Research Center Jin-Woo Han, Dong Moon, and M. Meyappan have developed a silicon-based NVCT with improved gate designs that reduce the control voltage from a few tens of volts to five.
In fact, the space inside the NVCT is not really a vacuum. It is filled with an inert gas (for example, helium at atmospheric pressure), in which electrons move. Since the distance between them does not exceed 50 nm, the probability of their collision with gas molecules is negligible, which allows electrons to move almost unhindered, as in a real vacuum.
In the future, scientists plan to improve the performance of NCVT transistors, improve their reliability and extend their service life.