Nanoscale Transistors Could Replace Silicon for Ultra Efficient Electronics

Researchers at MIT have made a breakthrough in developing nanoscale transistors that could enable more efficient electronics. By leveraging quantum mechanical properties, these transistors can operate at much lower voltages than conventional silicon-based devices, potentially paving the way for ultra-low-power artificial intelligence applications. The team, led by postdoc Yanjie Shao and senior author Jesús del Alamo, fabricated three-dimensional transistors using ultrathin semiconductor materials, achieving performance comparable to state-of-the-art silicon transistors while operating efficiently at much lower voltages. This technology has the potential to replace silicon, enabling faster computation with better energy efficiency. The researchers used a unique phenomenon in quantum mechanics called quantum tunneling, which allows electrons to penetrate barriers, and achieved sharp switching slopes and high current simultaneously by carefully controlling the 3D geometry of their transistors. This work is funded in part by Intel Corporation and has significant implications for the development of more efficient electronics.

Overcoming Silicon’s Limitations: Nanoscale Transistors for Efficient Electronics

The development of artificial intelligence (AI) technologies has led to an increased demand for faster computation and more efficient electronics. However, silicon semiconductor technology, which is currently used in most electronic devices, is held back by a fundamental physical limit known as “Boltzmann tyranny.” This limit prevents transistors from operating below a certain voltage, hindering the energy efficiency of computers and other electronics.

To overcome this limitation, researchers at MIT have fabricated a new type of three-dimensional transistor using ultrathin semiconductor materials. These devices feature vertical nanowires only a few nanometers wide and can deliver performance comparable to state-of-the-art silicon transistors while operating efficiently at much lower voltages.

Leveraging Quantum Mechanical Properties

The new transistors leverage quantum mechanical properties, such as quantum tunneling, to encourage electrons to push through the energy barrier rather than going over it. This allows for sharp switching slopes and high current simultaneously, making them suitable for demanding applications. The researchers believe that these are the smallest 3D transistors reported to date.

Quantum confinement, which occurs when an electron is confined to a space that is so small that it can’t move around, also plays a crucial role in the operation of these transistors. By engineering a very strong quantum confinement effect, the researchers were able to fabricate an extremely thin tunneling barrier, enabling high current.

Fine-Grained Fabrication

The precise control of the 3D geometry of the transistors was achieved using tools at MIT.nano, MIT’s state-of-the-art facility for nanoscale research. The engineers were able to carefully craft vertical nanowire heterostructures with a diameter of only 6 nanometers.

Fabricating devices that were small enough to accomplish this was a major challenge. The researchers had to develop techniques to achieve uniformity across an entire chip, as even a 1-nanometer variance can change the behavior of the electrons and affect device operation.

Performance and Future Directions

When tested, the sharpness of the switching slope of the new transistors was below the fundamental limit that can be achieved with conventional silicon transistors. The devices also performed about 20 times better than similar tunneling transistors.

The researchers are now striving to enhance their fabrication methods to make transistors more uniform across an entire chip. They are also exploring vertical fin-shaped structures, in addition to vertical nanowire transistors, which could potentially improve the uniformity of devices on a chip.

This research has significant implications for the development of efficient electronics and AI technologies. As Aryan Afzalian, a principal member of the technical staff at imec, notes, “This work definitively steps in the right direction, significantly improving the broken-gap tunnel field effect transistor (TFET) performance.”