Semiconductor chips are the backbone of modern electronics, powering everything from smartphones to laptops to cars. But as devices become smaller and more powerful, silicon — the material that most chips are made of — is reaching its physical limits. To overcome this challenge, researchers are exploring new materials that can enable faster and more efficient chips.
One promising candidate is 2D materials, which are atomically thin sheets of crystals that have unique electrical properties. Unlike silicon, which loses its conductivity when scaled down to nanometer sizes, 2D materials can maintain or even improve their performance at such scales. However, integrating 2D materials with existing silicon chips has been a major challenge, as conventional fabrication methods require high temperatures that can damage the underlying circuits.
Growing 2D materials on Silicon Wafers
Now, MIT engineers have developed a breakthrough technique that can grow 2D materials directly on top of silicon wafers, without damaging them. The technique, reported in a paper published in Nature on January 18, 2023, uses a low-temperature process that deposits atoms on a wafer coated with a “mask” that guides the growth of the 2D layers. The result is a perfect, single-crystalline 2D material that can be integrated with silicon circuits to create denser and more powerful chips.
The researchers demonstrated their technique by growing a type of 2D material called transition-metal dichalcogenides (TMDs) on an 8-inch silicon wafer. They then fabricated a simple transistor from the TMD layer and showed that it could operate faster and more efficiently than a silicon transistor of the same size.
“We expect our technology could enable the development of 2D semiconductor-based, high-performance, next-generation electronic devices,” says Jeehwan Kim, associate professor of mechanical engineering at MIT and the senior author of the paper. “We’ve unlocked a way to catch up to Moore’s Law using 2D materials.”
Extending Moore’s Law
Moore’s Law is the observation that the number of transistors on a chip doubles every year, leading to exponential improvements in computing power. However, this trend is predicted to plateau soon, as silicon transistors reach their physical limits. Kim and his colleagues believe that their technique could extend Moore’s Law by enabling chip manufacturers to stack multiple layers of 2D transistors on top of silicon circuits, creating 3D architectures that can pack more functionality into less space.
The researchers also envision that their technique could be used to grow other types of 2D materials, such as graphene and boron nitride, which have different properties and applications. For example, graphene is an excellent conductor of electricity and heat, while boron nitride is an excellent insulator. By combining different 2D materials on a silicon wafer, the researchers could create complex and multifunctional devices for various purposes.
“We can grow any kind of 2D material on any kind of substrate using our method,” Kim says. “This opens up a new world of possibilities for 2D electronics.”
Overall, the breakthrough technique developed by the MIT researchers represents a major step forward in semiconductor development. As the demand for faster and more powerful electronics continues to grow, the integration of 2D materials with existing silicon chips could enable the creation of smaller, more efficient, and more complex electronic devices, opening up a new world of possibilities for 2D electronics.
The following is a list of official sources that provide more information about the research:
Nature paper: “Nonepitaxial single-crystalline growth of atomically thin transistors on industrial wafers” (January 18, 2023). This is the original paper that describes the technique and its results in detail.
MIT News article: “MIT engineers grow “perfect” atom-thin materials on industrial silicon wafers” (January 18, 2023). This is a summary of the paper written for a general audience by MIT News Office.
MIT News article: “MIT engineers “grow” atomically thin transistors on top of computer chips” (April 27, 2023). This is an update on the paper that highlights its potential applications and implications for the electronics industry by MIT News Office.
