It is a sign of recovery to a vacuum tube replaced by a semiconductor, and it can be a trump card for ultra-high speed mobile communication & CPU realization?

ByTau Zero

It was used as an element of an electronic circuitVacuum tubeWas deprived of the leading role by the appearance of semiconductors, and it seemed to have completely stopped breathtaking with discontinuation of CRT production. But,American Aeronautics and Space Administration(NASA) adopted vacuum tube technology "Vacuum channel transistorIt is expected to realize ultrahigh-speed wireless communication and ultra-high-speed CPU, which are difficult to realize with semiconductor devices by vacuum tubes.

Introducing the Vacuum Transistor: A Device Made of Nothing - IEEE Spectrum
http://spectrum.ieee.org/semiconductors/devices/introducing-the-vacuum-transistor-a-device-made-of-nothing

NASA melds vacuum tube tech with silicon to fill the terahertz gap | Ars Technica
http://arstechnica.com/science/2014/06/nasa-melds-vacuum-tube-tech-with-silicon-to-fill-the-terahertz-gap/

How Vacuum Tubes, New Technology Might Save Moore's Law - HotHardware
http://hothardware.com/News/How-Vacuum-Tubes-New-Technology-Might-Save-Moores-Law-/

Computer of Suming machine developed in USA "ENIAC"I used 14,768 vacuum tubes, but it was a machine that required 150 kilowatts of power for 27 tons of bulk. The major reason for this power consumption is mainly due to vacuum tubes, it is said that one of the many used vacuum tubes was broken every day, which hindered the operation of ENIAC.


Large, bulky and more powerful and fragile Vacuum tubes are small, lightweight and have low power consumption semiconductorsA transistorAs soon as it appeared it disappeared from the front stage in the blink of an eye, now it has declined so much that there are no scenes used other than being handy for some audiophiles.

However, using the vacuum tube technology that was thought to be a relic of the past "Vacuum channel transistor"Currently, NASA is under development, it is expected that ultra-high speed wireless communication of hundreds of Gbps can be realized, and breakthrough of CPU performance that can be seen to limit can be caused.

The vacuum channel transistor has been improved to utilize the vacuum tube principle to make electrons flow between the gates without physically contacting by creating a vacuum gap with an emitter-collector spacing of 150 nanometersMOSFETIt is a substitute for. In the conventional vacuum tube, changing the gap between the electrodes, which was a millimeter scale, to the nanometer scale greatly reduces the frequency of collisions of gas with gas molecules present in the vacuum gap, which means that no vacuum treatment is required .


Furthermore, by minimizing it to the nanoscale, it becomes unnecessary to release thermionic electrons which is required in the conventional vacuum tube,CathodeWe have succeeded in emitting electrons only by placing the cathode (cathode) in an electrostatic field. In other words, thanks to the minimization of the electrode part to the nanoscale, we have succeeded in eliminating not only the size of the element but also eliminating the drawback of "electric power eaten" stuck to a conventional vacuum tube.

NASA has developed a vacuum channel transistor, which is a vacuum tube of extremely small size, because the durability in outer space was a major reason. Space is a high energy radiation (Electron beam) Are in a harsh environment, so the arrow of bare feet stands in a vacuum tube excellent in durability.

ByNASA's Marshall Space Flight Center

The vacuum channel transistor under development by NASA has already succeeded in super high speed operation of 460 GHz, and it is expected to realize ultrahigh speed CPU utilizing this technology. In silicon-based semiconductors, which are now mainstream, limitations are beginning to appear in microfabrication technologies and will continue to beMoore's lawIt seems to be said that the possibility of vacuum channel transistor is hidden where large breakthrough is necessary to maintain.

Also, at an ultra high speed of several hundred GHzoscillationIt is thought that the vacuum channel transistor that can be applied to the wireless communication in the terahertz band (300 GHz to 3 THz). In the terahertz band, it is difficult to manufacture a wave source device in a frequency band around 300 micrometers (1 THz in frequency), so it is hardly used, but it can be used for ultrahigh-speed wireless communication of tens of Gbps It is considered.

The terahertz band of 300 GHz to 3 THzTerahertz gap(Terahertz gap) called "valley" of infrared electromagnetic spectrum which practical technique does not exist yet.


According to NASA, the driving voltage of the vacuum channel transistor is as high as 10 V, so we need to further improve the low voltage in the future and develop a manufacturing technology for mass production in the future.