When a trio of engineers led by Bill Shockley built the first solid-state transistor at Bell Labs in 1947, they thought they had consigned the vacuum tube to oblivion. Bell Labs’ owner at the time AT&T wanted a replacement for the fragile and bulky glass tubes that powered Ma Bell’s innumerable switches. What Shockley and company created, however, was the foundation of all modern electronics.
Today you’ll only find a vacuum tube in a guitar amp or by rooting around in your grandfather’s old Hi-Fi. But vacuum tubes – or at least their underlying principles – may be set to make a resurgence. A team of researchers at the University of Pittsburgh are investigating the possibility of replacing silicon with vacuums as the medium for electron transport in an effort to build faster and more efficient electronic machines.
As Moore’s Law shrinks down the transistor to nanometer size on today’s integrated circuits, the electrons are running out of space to move around, explained principle investigator Hong Koo Kim in a Pitt news release:
The ultimate limit of transistor speed, says Kim, is determined by the “electron transit time,” or the time it takes an electron to travel from one device to the other. Electrons traveling inside a semiconductor device frequently experience collisions or scattering in the solid-state medium. Kim likens this to driving a vehicle on a bumpy road—cars cannot speed up very much. Likewise, the electron energy needed to produce faster electronics is hindered.
The best way to avoid that kind of scattering is to use no medium at all, either a “vacuum or the air in a nanometer scale space.” Kim said. “Think of it as an airplane in the sky creating an unobstructed journey to its destination,” he said.
Kim isn’t advocating a return to the old red-hot vacuum tube, rather he and his team are building on today’s silicon foundations. They’re developing a method in which electrons can be extracted from semiconductors into the air and then directed via vacuum channels over the surface of the circuit.
If the Pitt researchers can develop a commercially viable vacuum channel technology, it could mean another revolution in microelectronics, creating a new class of high-speed and low-power transistors. That would allow chipmakers to keep riding Moore’s Law and device makers to build more powerful computers, smartphones and tablets that drain less energy.
Kim’s team published their conclusions this month in the journal Nature Nanotechnology. But for a more concise – and entertaining – explanation of their efforts check out the Nation Science Foundation’s podcast on the top: Vac to the Future.
Photo courtesy of Shutterstock user SPbPhoto