Researchers Create 'Few Atoms Thick' Semiconductors for Solar Cells and Circuits

Over the past half-century, Researchers have shaved silicon films down to merely a strand of atoms in the quest of smaller, faster electronics. For the next set of innovations, though, they will need unique ways to construct even tinier and more robust devices.

A new method allows Scientists to craft individual tiny films, each just a few atoms high, and stack them for new kinds of electronics. (Illustration by UChicago Creative)

In a paper published in the September 20th issue of Nature, UChicago and Cornell University Researchers describe an innovative technique to create stacks of semiconductors just a few atoms thick. The method offers Engineers and Scientists a simple, economical approach to make thin, uniform layers of these materials, which could increase capabilities for devices from cell phones to solar cells.

Stacking thin layers of materials provides a variety of possibilities for producing electronic devices with unique properties. However, manufacturing such films is an intricate process, with minimal room for error.

The scale of the problem we’re looking at is, imagine trying to lay down a flat sheet of plastic wrap the size of Chicago without getting any air bubbles in it. When the material itself is just atoms thick, every little stray atom is a problem.

Professor Jiwoong Park, the Department of Chemistry, the Institute for Molecular Engineering and the James Franck Institute, The University of Chicago, who led the study

Today, rather than stacking them on top of one another, these layers are “grown”. But that means the bottom layers have to be exposed to harsh growth conditions such as elevated temperatures while the new ones are included—a process that confines the materials with which to make them.

Park’s team instead formed the films individually. Then they placed them into a vacuum, peeled them off and stuck them to one another, like Post-It notes. This allowed the Researchers to form films that were linked with weak bonds instead of stronger covalent bonds—meddling less with the flawless surfaces between the layers.

The films, vertically controlled at the atomic-level, are exceptionally high-quality over entire wafers.

Kibum Kang, a Postdoctoral Associate, The University of Chicago and First Author

Kan-Heng Lee, a Graduate Student and Co-first Author of the study, then tested the films’ electrical properties by converting them into devices and demonstrated that their functions can be developed on the atomic scale, which could allow them to serve as the vital ingredient for advanced computer chips.

The technique opens up countless possibilities for such films. They can be made on top of plastics or water; they can be engineered to detach by dipping them into water; and they can be patterned or carved with an ion beam. Researchers are investigating the whole range of what can be done with the technique, which they said is simple and economical.

We expect this new method to accelerate the discovery of novel materials, as well as enabling large-scale manufacturing.

Professor Jiwoong Park, the Department of Chemistry, the Institute for Molecular Engineering and the James Franck Institute, The University of Chicago, who led the study

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