How small can a transistor get?

For decades, engineers have been working to create smaller and smaller transistors to fit ever-larger numbers of them onto computer chips, all in the name of greater processing power.

Now, in the age of artificial intelligence (AI), that effort has turned into an all-out race.

So how small can a transistor actually get? And is smaller even still the goal? To understand the answer, first you need to know what a transistor is.

"If you take a computer or your mobile phone and you were to pry it open, you will see that there is a printed circuit board," Suman Datta , a professor of electrical and computer engineering at Georgia Tech, told Live Science.

On that circuit board are small, rectangular objects called chips, and inside each chip is a tiny piece of silicon.

"And in that silicon, if you zoom in like a million times … maybe, if you're lucky, you will start seeing these tiny switches or transistors sitting etched into that piece of silicon," Datta said.

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Each transistor is effectively a switch that turns on and off in response to jolts of electricity pulsing 4 billion times per second.

Modern devices contain billions of transistors, and each one turning on and off in a precise orchestration to move and store 1s and 0s powers everything from Google searches and AI data centers to the device you're using to read these words.

The smaller the transistors are, the more can fit on each chip and the greater the chip's speed and functionality.

So how small have they gotten so far? Transistors were once visible to to the naked eye, but have now been made orders of magnitude smaller than the width of a human hair. (Image credit: Bettmann via Getty Images) "Researchers have built proof-of-concept devices in which a single atom controls the flow of electrons, although the rest of the device is still much larger," Anton Persson , an assistant professor at Chalmers University of Technology in Sweden, and Tara Peña , an incoming assistant professor at UCLA, told Live Science via a jointly written email.

That means the switching part of a transistor has been made at the smallest scale physically possible, even though a complete device that small doesn't exist yet.

New materials and approaches could make these devices even smaller.

In a study published in June in the journal Nature Nanotechnology , Persson, Peña and colleagues used two-dimensional semiconductors made of tungsten disulfide, among other materials, to shrink nanoribbon transistors down to a channel width of 25 nanometers ‪—‬ about 0.00025 the width of a human hair.