Abstract
Many computational models have been developed to predict the rates of atomic displacements in two-dimensional (2D) materials under electron beam irradiation. However, these models often drastically underestimate the displacement rates in 2D insulators, in which beam-induced electronic excitations can reduce the binding energies of the irradiated atoms. This bond softening leads to a qualitative disagreement between theory and experiment, in that substantial sputtering is experimentally observed at beam energies deemed far too small to drive atomic dislocation by many current models. To address these theoretical shortcomings, this paper develops a first-principles method to calculate the probability of beam-induced electronic excitations by coupling quantum electrodynamics (QED) scattering amplitudes to density functional theory (DFT) single-particle orbitals. The presented theory then explicitly considers the effect of these electronic excitations on the sputtering cross section. Applying this method to 2D hexagonal BN and MoS2 significantly increases their calculated sputtering cross sections and correctly yields appreciable sputtering rates at beam energies previously predicted to leave the crystals intact. The proposed QED-DFT approach can be easily extended to describe a rich variety of beam-driven phenomena in any crystalline material.
| Original language | English |
|---|---|
| Pages (from-to) | 1053-1067 |
| Number of pages | 15 |
| Journal | Nanoscale |
| Volume | 15 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jun 3 2022 |
Funding
Calculations were performed at the Center for Computational Innovations at Rensselaer Polytechnic Institute, Livermore Computing Center at Lawrence Livermore National Laboratory (LLNL), and Compute and Data Environment for Science at Oak Ridge National Laboratory (ORNL), which is supported by the Office of Science of the U.S. Department of Energy (DOE) under Contract No. DE-AC05-00OR22725. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344. This material is also based upon work supported by the U.S. DOE, Office of Science, Office of Workforce Development for Teachers and Scientists, Office of Science Graduate Student Research (SCGSR) program. The SCGSR program is administered by the Oak Ridge Institute for Science and Education for the DOE under contract number DE-SC0014664. Funding was provided by the National Science Foundation (Award 1608171). Work (BGS, PG, DL, JJ) was also supported by ORNL's Center for Nanophase Materials Sciences, a U.S. DOE Office of Science User Facility.