NASA’s high-speed transistor uses same principle as vacuum tubes

Ars Technica : Vacuum tubes were a key piece of many electronics prior to the development of transistors. They consisted of two electrodes—the cathode and the anode—separated by a grid that controlled the rate of current flow based on the voltage supplied. To cause the cathode to release electrons it had to be heated, which drew a lot of power. The entire setup was arranged in a vacuum in an airtight glass bulb to prevent the electrons from ionizing atoms between the electrodes. Now, researchers at NASA have created a nanoscale transistor that structurally resembles a vacuum tube. However, because of its small size—the electrodes are separated by nanometers instead of millimeters—there is no need for a vacuum because there is little chance that any electrons will be able to collide with air molecules. It also doesn’t require a heating element; electrons can be released by placing the cathode in a static electric field. The resulting prototype vacuum-channel transistor has a switching speed of 460 GHz. That puts it in the frequency range between 100 GHz and 10 THz, known as the terahertz gap , in which traditional transistors have difficulty sending and detecting signals. Transistors operating in this range could allow for the creation of devices used for imaging and signal detection in a part of the spectrum that had been hard to access.