Nanoscale Vacuums Speed Semiconductors

A new class of low-power, high-speed transistors could be on the horizon, thanks to the vacuum

2 min read
Nanoscale Vacuums Speed Semiconductors

When you want to make the point of how far electronics and computer technology have come in the last sixty years, you likely refer to the old computers that used vacuum tubes for circuitry.

So, it’s a bit counterintuitive to see the latest research that suggests vacuums may be the way forward to help semiconductor electronics keep pace with Moore’s law. Researchers at the University of Pittsburgh have developed a method for generating a vacuum within a semiconductor device to transport electrons more efficiently through it. 

“Physical barriers are blocking scientists from achieving more efficient electronics,” said Hong Koo Kim, principal investigator on the project and Bell of Pennsylvania/Bell Atlantic Professor in the University of Pittsburgh’s Swanson School of Engineering, in a press release. “We worked toward solving that road block by investigating transistors and its predecessor—the vacuum.”

Of course, there already exist vacuum electronic devices, but these require high voltage. The researchers, who published their findings in the journal Nature Nanotechnology, designed an entirely new vacuum electronic device that requires minimal voltage to operate.

The key to the design was the discovery by Kim's team that it was fairly easy to pull electrons out into the air when they are trapped at the interface of an oxide or metal layer inside a semiconductor. These trapped electrons form a two-dimensional electron gas.

The researchers exploited the phenomenon known as Coulombic Repulsion--the repulsive force between two positive or negative charges--to emit the electrons from this electron gas layer. By then applying a small voltage of  1V to the silicon structure, the electrons were extracted into the air, which made it possible for them to travel ballistically in a nanometer-scale vacuum channel without the scattering typically seen in conventional devices.

Kim further noted in the release, “The emission of this electron system into vacuum channels could enable a new class of low-power, high-speed transistors, and it’s also compatible with current silicon electronics, complementing those electronics by adding new functions that are faster and more energy efficient due to the low voltage."

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The Ultimate Transistor Timeline

The transistor’s amazing evolution from point contacts to quantum tunnels

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A chart showing the timeline of when a transistor was invented and when it was commercialized.

Even as the initial sales receipts for the first transistors to hit the market were being tallied up in 1948, the next generation of transistors had already been invented (see “The First Transistor and How it Worked.”) Since then, engineers have reinvented the transistor over and over again, raiding condensed-matter physics for anything that might offer even the possibility of turning a small signal into a larger one.

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