Researchers from Applied Electromagnetics Group at the University of California San Diego have succeeded in building a microelectronic device without the incorporation of semiconductors for the first time at least in a published paper.

The team published its findings in Nature Communications this week explaining how they were able to engineer an optically-controlled device that bypassed by the use of semiconductors by thinking of and employing a metasurface in the nanoscale that avoids the limits that superconductors bring to electron flow or, perhaps more familiar, conductivity. Electrons have a pesky habit of running into a number of atoms on their way to a given point in a semiconductor, but the team worked out a vacuum tube 2.0 that avoids the limitations placed on power handling and speed that semiconductors bring.

(In Layman’s Terms) Semiconductors based on silicon and other materials are great, obviously, having helped us squeeze billions of transistors into a few square inches. But they have some issues: Electron velocity is limited by the resistance of semiconductor materials, and a boost of energy is required to just to get them flowing through the “band gap” caused by the insulating properties of semiconductors like silicon. Vacuum tubes don’t have those problems, since they dislodge free electrons to carry (or not) a current through space. Getting free electrons at nanoscale sizes is problematic, however — you need either high voltage (over 100 volts), high temperatures or a powerful laser to knock them loose. The UC San Diego team solved that problem by building gold “mushroom” nanostructures with adjacent parallel gold strips (above). By combining a relatively low amount of voltage (10 volts) with a low-powered laser, they were able to dislodge electrons from the gold metal.

Moore’s Law dictates that computing speeds double every two years and are meant to see a consequent drop in cost and the team recognizes that they are on to something impractical beyond their existing accomplishment.

Source: UC San Diego