This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A team of researchers led by the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) developed an approach that enabled them to directly observe how electrons interact with defects in advanced semiconductor devices in unprecedented detail.
The team's methodology included an innovative simulation tool that enabled accurate theoretical interpretations of its experimental observations. The study, published in Nature, focuses on cutting-edge ultrathin devices known as two-dimensional (2D) semiconductors that have unusual electron states. "Our study yielded valuable insights into why electrons in 2D semiconductors behave the way they do," said Mike Crommie, a senior faculty scientist in Berkeley Lab's Materials Sciences Division and professor of physics at UC Berkeley, and one of the study's authors.
"Our methods open the door to the discovery of never-seen-before electron behaviors that can be used for new semiconductor capabilities. This will be important for the future development of semiconductor devices at the ultimate limits of miniaturization." Other research team members include Feng Wang, a faculty senior scientist in Berkeley Lab's Materials Sciences Division and a professor in UC Berkeley's Department of Physics, and scientists from the University of California, the Flatiron Institute, the University of New Mexico, Hofstra University, Arizona State University and the National Institute for Materials Science (Japan). Conventional silicon-based semiconductor devices, such as transistors, computer chips and sensors, are made of materials in which atoms are arranged in three-dimensional structures.
In recent years, device developers have increasingly explored the possibility of using 2D semiconductors, which are materials made of just a single layer—or a few layers—of atoms. Their ultrathin structure changes how electrons behave, potentially enabling new capabilities in future semiconductor devices. The Berkeley Lab–led research team investigated 2D materials in which the electrons are in an unusual state known as a Wigner solid.
In ordinary semiconductor devices, electrons typically behave like independent particles moving through the material. Their interactions with one another have a relatively minor influence on their behavior—and on the overall operation of the device. "Physicists call this conventional state a Fermi liquid because the electrons move around like waves in the ocean," said Crommie.
Under certain conditions, electrons can enter a Wigner solid state in which they separate from one another and become immobile. Physicists describe such a system as "strongly interacting" because the electrons' mutual repulsion becomes the dominant factor shaping their behavior. Rather than moving independently, electrons in Wigner solids organize themselves into a relatively orderly pattern and behave collectively as a group.
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