Some of the predicted 2D semiconductors with very high carrier mobility at room temperature. Image: The University of Texas at Austin.
Some of the predicted 2D semiconductors with very high carrier mobility at room temperature. Image: The University of Texas at Austin.

Two-dimensional (2D) semiconductors have the chance to galvanize significant advances in the capabilities of electronic devices, by replacing silicon-based chips. However, many problems continue to hold back these materials.

One major problem is carrier mobility, or how fast electrons can move through the semiconductors. Because 2D semiconductors are notoriously slow in this area, limiting the ability for improvements and real-world applications.

But now researchers at the University of Texas at Austin have discovered more than a dozen different 2D semiconductor materials that could allow electrons to move around quickly, opening the door for a leap in the capabilities of electronic devices.

"If you can replace silicon with 2D semiconductors that will lead to faster devices that consume significantly less energy," said Yuanyue Liu, an assistant professor in the Cockrell School of Engineering's Walker Department of Mechanical Engineering and the Texas materials Institute, who led the project. Liu and his colleagues report their work in a paper in Physical Review Letters.

The big difference between traditional silicon-based semiconductors and 2D semiconductors is their geometry – 2D semiconductors are much thinner, only a couple of atomic layers thick. This is advantageous in many ways as the push to make semiconductors smaller continues to pick up steam.

Unfortunately, the compact nature of 2D semiconductors creates problems as well, as it means the electrons are packed in tight, without much freedom to move. Scattering sources can more easily knock the electrons off track in these smaller spaces, which is why carrier mobility is generally low in 2D semiconductors, preventing improved power and efficiency.

The 14 materials with high carrier mobility discovered by the researchers are an exception to this rule. Unique properties among these materials make the electrons more transparent, rendering them essentially invisible to scatterings and allowing them to stay on course.

To find these materials, the researchers used an existing materials database and a checklist of characteristics that they hypothesized would lead to improved mobility. They then used quantum-mechanical methods to accurately calculate the carrier mobility in the materials.

"The fact that we only found 14 materials with potentially high carrier mobility out of thousands does not contradict the conventional wisdom," Liu said. "It shows how difficult it is to find 2D semiconductors with high carrier mobility."

The next step for Liu and his colleagues is to partner with experimental researchers and work on fabricating these materials to test and verify their findings. Though Liu is confident in the findings, he cautioned that they are still theoretical and will need to be confirmed by real-world testing.

This story is adapted from material from the University of Texas at Austin, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.