Two-dimensional materials such as graphene could form the basis for incredibly small and fast technologies, but this requires a detailed understanding of their electronic properties. New research shows that fast electronic processes can be probed by first irradiating materials with ions.
A joint study involving researchers at the University of Illinois Urbana-Champaign and the University of Duisburg-Essen showed that the electrons emitted when graphene is irradiated with ions or electrically charged atoms provide information about the electronic behavior of graphene. I gave it to you.
Additionally, the Illinois group performed the first calculations involving high-temperature graphene, and the Duisburg-Essen group investigated and experimentally verified the predictions. The study was reported in the journal Nano letters.
“Inferring what is happening inside a material by examining it and observing changes in its properties is a well-established technique, but we are now taking the first step in using ions instead of laser light for this purpose,” said Illinois group André Schleife. .” he said. He is a professor and senior professor of materials science and engineering.
“The advantage is that it allows highly localized and short-duration excitation of ions in materials compared to what laser light can do. This allows high-precision studies of how graphene and other 2D materials evolve over time. it's possible.”
When ions collide with two-dimensional matter, energy is transferred to both the nuclei and electrons. Some electrons are given enough energy to be ejected from the material. The properties of these so-called “secondary electrons” are determined by the properties of electrons in the material, such as temperature and energy distribution.
“There is a delay between the ‘impact’ of the ion and the secondary electron emission, and this is the key information we were looking for in the simulations,” said Yifan Yao, lead author of the study and a graduate student in Schleife’s research group. “We have done this for graphene that has thermal energy and higher temperatures, as well as graphene at absolute zero, where no thermal energy is present. In fact, we are the first to simulate 'hot' graphene like this. .”
The Illinois group performed calculations based on graphene irradiated with hydrogen ions (bare protons) and calculated how secondary electrons are emitted over time and the resulting energy spectrum. These results were in good agreement with those of the Duisburg-Essen group using argon and xenon ions.
Additionally, computational studies provide insight into the mechanisms underlying secondary electron emission. High-temperature graphene emitted more secondary electrons, and closer examination of the charge distribution indicated that the atomic nuclei in the material's lattice were responsible, rather than the material's electrons.
According to Schleife, the potential of this technology goes beyond precise 2D material measurements. “Looking into the future, there is the possibility of using ion irradiation to intentionally introduce and manipulate defects in materials,” he said. “But in the near term, we have shown that irradiation can be used as a high-precision measurement technique.”
Additional information:
Yifan Yao et al., Non-equilibrium dynamics of electron emission from low- and high-temperature graphene under proton irradiation; Nano letters (2024). DOI: 10.1021/acs.nanolett.4c00356
Provided by University of Illinois Granger School of Engineering
Summons: Ion irradiation offers promise for probing 2D materials (May 17, 2024). Retrieved May 19, 2024, from https://phys.org/news/2024-05-ion-irradiation-2d-material-probing.html
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