Beyond Moore’s Law: Vacuum Tubes?

By Shlomo Maital

  vacuum tube

Vacuum tube

   Sometimes, you can innovate by going back to the future. Take, for instance, the transistor. They are getting ever smaller, and more and more of them are packed into a microprocessor.   Semiconductor companies like Intel now work in 10 to 20 nanometer dimensions (a DNA strand is about 2.5 nanometers).   Below 10 nanometers, who knows how silicon will behave?  At those dimensions, it starts to emit light and becomes very flexible.

   Almost half a century ago, Intel founder Gordon Moore stated his famous law, that the number of transistors that could be etched into silicon wafers would double every 18 months or so. This has held true, remarkably. But it seems we are approaching the limit of Moore’s Law. The smaller transistors get, the more they leak electrons. This causes wasted power (up to half the power consumed by microprocessors is lost when electrons leak), and generates a lot of heat, which in turn requires massive cooling.

     Dr. Axel Scherer, a Caltech scientist, is working on a solution. He and two students have gone back to the vacuum tube. Vacuum tubes (“valves” in Britain) are devices that control electric currents between electrodes in an evacuated container;   electrons are emitted from a hot filament or a cathode heated by the filament. They are big, clunky and creating the vacuum is costly. But Scherer creates tiny tubes of metal, able to turn flows of electrons on and off between four very tiny probes. What is neat about this is that you do not need to use silicon, and the very ‘leakage’ of electrons that bedevils tiny transistors actually is the basis of the nano-vacuum tube substitute for transistors.    It reminds me of Dov Frohman’s invention of flash memory.  He was asked to solve a problem of stray electrons on the surface of silicon microprocessors, solved it, but realized you could make use of those electrons, as a way to store information.  Flash memory is now ubiquitous. 

   Could these tiny vacuum tubes help us keep Moore’s Law in business? Stay tuned. Meanwhile, think about other old technologies that can be adapted to create massive value in new ways.

   Source:   “Shrinking computer chips, thanks to grandma’s radio tubes”. NYT, John Markoff, Monday June 6, 2016

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