MIT researchers have made a big breakthrough in creating new, incredibly small transistors that could improve electronics’ speed and efficiency.
Transistors are essential parts of most electronic devices, such as smartphones and computers, where they help to amplify and switch electrical signals.
Typically, these transistors are made from silicon, but silicon has physical limits that prevent it from operating below a certain voltage, reducing energy efficiency.
This limit, known as “Boltzmann tyranny,” limits how efficiently electronics can operate—especially as demand for faster, AI-powered devices grows.
To overcome this limit, the MIT team has developed a different type of transistor using advanced materials and a nanoscale design.
These transistors use tiny vertical nanowires—each only a few nanometers wide—that allow them to operate at much lower voltages than silicon-based transistors, making them far more energy-efficient.
The study, led by MIT postdoc Yanjie Shao and published in Nature Electronics, shows that these new transistors could eventually replace silicon in many electronics.
“This technology has the potential to replace silicon, offering the same functions with better energy efficiency,” explains Shao.
The design relies on quantum mechanical properties to achieve both high performance and low-voltage operation within a tiny area, which could make electronics faster, smaller, and more energy-efficient.
Traditional silicon transistors work by switching from “off” to “on” when a certain voltage is applied, allowing electrons to cross an energy barrier.
This process, called switching, is essential for digital devices, which operate using binary code (1s and 0s). The less voltage required for switching, the more energy-efficient the transistor. However, Boltzmann tyranny requires a minimum voltage for switching, limiting silicon’s efficiency.
To bypass this limit, MIT researchers used alternative semiconductor materials—gallium antimonide and indium arsenide—and applied a principle of quantum mechanics called quantum tunneling.
Quantum tunneling allows electrons to “tunnel” through barriers, instead of having to go over them, which enables low-voltage operation. The researchers crafted tunneling transistors that take advantage of this property, allowing the device to switch on and off with minimal energy.
However, tunneling transistors traditionally have a drawback: they operate with low current, limiting their power. To address this, the MIT team focused on fine-tuning the transistor’s design.
The team achieved this breakthrough at MIT.nano, MIT’s facility for nanoscale research. They built the transistors with vertical nanowire structures just 6 nanometers in diameter, the smallest 3D transistors reported to date.
This precise engineering allows them to achieve a sharp switching slope, meaning the device can switch on and off more steeply, which boosts energy efficiency.
This design relies on “quantum confinement”—when electrons are confined to a tiny space, they behave differently, gaining a smaller “effective mass.” This change allows electrons to tunnel more effectively through barriers, even at low voltage.
By controlling the 3D structure of the transistor so precisely, the researchers created a strong quantum confinement effect that lets more current pass through, increasing the transistor’s power without requiring more energy.
“We achieved a sharp switching slope and high current simultaneously by creating a very thin tunneling barrier,” says Shao.
The researchers tested these nanoscale transistors and found they had a sharper switching slope than what is possible with silicon transistors, performing about 20 times better than other similar tunneling transistors.
This research marks an exciting step in the development of nanoscale transistors, but there’s still work to be done before they can be used commercially.
The team is now refining their fabrication methods to make these tiny transistors uniform across an entire chip, as even a 1-nanometer difference can change electron behavior and affect the device’s performance. They’re also exploring alternative structures, like vertical fin shapes, which could improve the uniformity and performance of these devices on chips.
If successful, these nanoscale transistors could pave the way for faster, more powerful, and energy-efficient electronics, helping to meet the rising demands of the digital world.
Source: MIT.
