Vacuum tubes could be returning, but it may be difficult to see them--no glass bulbs with glowing filaments this time. An international team of researchers from NASA's Ames Research Center at Moffett Field, Calif. and the National Nanofab Center in Korea have created a “nano-tube,” a vacuum channel transistor that combines the faster electron transit time and resistance to radiation of vacuum tubes with the small size and lower voltage requirements of transistors.
The vacuum channel transistor is only 150 nanometers long and can be manufactured using conventional semiconductor fabrication techniques. The small size allows it to operate with less than 10 Volts on the “plate,” and the researchers believe they can reduce this to about a Volt, making it competitive with moderns emiconductor technology.
The American Institute of Physics news release did not mention if these nano-tubes use a triode, tetrode or pentode configuration, or perhaps something completely different. More information should be available in the paper "Vacuum nanoelectronics: Back to the future?" – Gate insulated nanoscale vacuum channel transistor available for purchase on the AIP website. If these devices ever become commercially available, I wonder if we'll someday see a vacuum channel transistor equivalent of the ever-popular 12AX7.
