Atomic Scale Dopant Control

The ability to construct new materials starting from the scale of single atoms could potentially enable new materials and technologies. However, this process involves two separate challenges: How to see where the atoms are, and then how to control where they go. The scanning transmission electron microscope (STEM) provides an answer to the first challenge, with the Z-contrast imaging mode able to reveal the structure and bonding of a variety of materials. Perhaps even more excitingly, the STEM might also provide an answer to the second challenge of how to control the position of the atoms.<br/>Working in a high-vacuum system, the atomic-scale probe size obtained in an aberration-corrected STEM allows single atoms to be manipulated in and on a variety of materials, with examples including heavy dopant atoms inside silicon crystals, and a variety of different atoms in graphene. Recent work has highlighted the potential for this technique [1], elucidated the underlying mechanisms [2], and extended the range of elements that can be used [3]. Nevertheless, numerous challenges remain, such as: How do we find the ideal conditions? How do we control the supply of dopants? And to what extent can the atoms be positioned where we want them? [4]<br/><br/><br/>[1] B. Hudak, et al. Directed Atom-by-Atom Assembly of Dopants in Silicon, ACS Nano 12(6) (2018) DOI:10.1021/acsnano.8b02001<br/>[2] A. Markevich, et al, Mechanism of Electron-Beam Manipulation of Single-Dopant Atoms in Silicon, J. Phys. Chem. C (2021), 125, 29, 16041–16048 DOI:10.1021/acs.jpcc.1c03549<br/>[3] O. Dyck, et al. Doping transition-metal atoms in graphene for atomic-scale tailoring of electronic, magnetic, and quantum topological properties, Carbon, 173, (2021), https://doi.org/10.1016/j.carbon.2020.11.015.<br/>[4] This material is based upon work supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division and was performed at the Oak Ridge National Laboratory’s Center for Nanophase Materials Sciences (CNMS), a U.S. Department of Energy, Office of Science User Facility.