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O: Fachverband Oberflächenphysik
O 5: Focus Session: Ion Beam Interaction with Surfaces and 2D Materials I
O 5.2: Vortrag
Montag, 27. März 2023, 11:00–11:15, GER 38
Model for Nanopore Formation in Two-Dimensional Materials by Impact of Highly Charged Ions — •A. S. Grossek, A. Niggas, R. A. Wilhelm, F. Aumayr, and C. Lemell — TU Wien
Experiments of highly charged ions (HCI) on 2D-materials have shown that HCIs extract numerous electrons from the 2D target. This interaction has shown to lead to nanopore formation in materials such as monolayer MoS2 while single layer graphene remains structurally intact. One hypothesis proposed for the cause of nanostructuring of these materials is charge build up by hole charges in the target, which -depending on material charge conductivity- may sustain sufficiently long in order to lead to structural damage of the target atoms. We study this hypothesis of nanostructuring by HCI impact on 2D-materials via molecular dynamics simulations. The charge transfer from target to HCI is well described by the classical-over-the-barrier model, of which a simplified version is implemented into the simulation. Charge conduction in the target is modelled by charge hopping with a hopping time th between lattice sites. Our 2D lattice is simulated by a Stillinger-Weber potential with parameters fitted to reproduce graphene. We study different materials by respectively adjusting the hopping time th (conductivity) of the graphene lattice in the simulation. After the simulation kinetic and potential energies of the individual target atoms are evaluated to determine if a pore has formed. Our simulation is able to qualitatively reproduce experimental results showing pore formation efficiencies and pore sizes to be dependent on initial HCI charge state and conductivity of the material.