Why it matters: Silicon transistors are great, but just like any other object in the physical world, they are held back by a few limitations. The laws of physics put a bottleneck on performance and energy efficiency. Now, a group of MIT engineers may have found a way to blow past those limits using a radical new transistor design that behaves in wild quantum ways.

The problem they're tackling is what's known as "Boltzmann tyranny." It refers to the fundamental limit to how little voltage is required to switch a silicon transistor on and off at room temperature, where if you crank the voltage down too far, the transistor loses its switching ability. This voltage floor prevents major gains in energy efficiency for electronics, which could be a problem as power-hungry AI applications take over more processing duties.

The MIT team fabricated experimental transistors from unique semiconductor materials like gallium antimonide and indium arsenide, rather than traditional silicon. The research is funded, in part, by Intel Corporation and was published recently in Nature Electronics.

However, the real magic is in their unique tiny 3D design, engineered with precision tools at MIT.nano, the university's dedicated facility for nanoscale research. The transistors feature vertical nanowire heterostructures with a minuscule diameter of just 6 nanometers, which the researchers believe are the smallest 3D transistors ever reported.

At that scale, some quantum effects come into play that let the transistors bypass the physical limits of silicon. The scientists designed the transistors to achieve quantum tunneling, where electrons can basically teleport across an insulating barrier layer rather than going over it, letting the transistor switch on with much less voltage. Another effect is quantum confinement, where the nanowire's cramped dimensions tweak the properties of the materials.

Combining those effects let the MIT devices pull off something silicon can't achieve: blazing fast switching times using very little voltage. Testing showed their slope of switching voltage was steeper than conventional silicon's limits. In fact, the current performance was around 20 times better than other experimental tunneling transistors.

"This is a technology with the potential to replace silicon, so you could use it with all the functions that silicon currently has, but with much better energy efficiency," says lead author Yanjie Shao, a postdoc on the project.

Of course, it's a long road from proof-of-concept to commercialization, and the team acknowledges this.

"With conventional physics, there is only so far you can go. The work of Yanjie shows that we can do better than that, but we have to use different physics. There are many challenges yet to be overcome for this approach to be commercial in the future, but conceptually, it really is a breakthrough," says senior author of the paper, Jesús del Alamo from the MIT Department of Electrical Engineering and Computer Science.

The team also notes that they need to refine manufacturing to make the nanoscale transistors more uniform across an entire chip.

This isn't the first time that MIT has worked to overcome the limits of Moore's Law. Earlier this year, MIT scientists showed off a transistor with the ability to switch within nanoseconds, boasting a billion-cycle durability.