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Defect engineering in two-dimensional materials: from fundamentals to applications

Ghorbani Asl, M.

It is well known that defects have a remarkable influence on the properties of 2D materials, including optical, electrical, thermal, and mechanical properties. Irradiation with electron and ion beams allows precise control of defect generation by altering beam conditions and exposure dose. Although the response of bulk targets to ion irradiation has been extensively investigated, much less is known about the effects of ion bombardment on 2D materials.
We have studied the effects of ion irradiation on 2D materials by using analytical potential molecular dynamics combined with Monte Carlo simulations. In particular, we focused on the defect production mechanisms and characterized different types of defects in transition-metal dichalcogenides. The amount of damage in MoS2 by the impacts of noble gas clusters was explored for a wide range of energies and incident angles. It was found that the behavior of free-standing and supported 2D materials under the ion beam can be quite different, as the backscattered ions or atoms sputtered from the substrate can completely govern defect production. We showed that cluster irradiation can be used to produce uniform pores in 2D MoS2 with the diameter being dependent on cluster size and energy.6 Ion beam irradiations can also be used to displace sulfur atoms preferentially from either top or bottom layers of S atoms in MoS2 and also clean the surface from adsorbents. The possibility of changing defect concentrations or inducing local amorphization of a 2D material opens a path for tuning its physical properties via a combination of thermal treatment and a reactive vapor. These findings help to understand the fundamental physical mechanisms underlying ion irradiation of low-dimensional materials, which opens many opportunities for the beam-mediated engineering of the devices and nanomeshes for, e.g., DNA sequencing or molecule separation.

Keywords: two-dimensional materials; defects; ion irradiation; molecular dynamics simulations

  • Invited lecture (Conferences) (Online presentation)
    IV Internatiol Symposium Modern Materials Science, 17.11.2020, Moscow, Russia

Permalink: https://www.hzdr.de/publications/Publ-32235
Publ.-Id: 32235