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O: Fachverband Oberflächenphysik

O 58: 2D materials beyond graphene: TMDCs, silicene and relatives II

O 58.7: Vortrag

Mittwoch, 14. März 2018, 12:00–12:15, MA 043

Defect production in supported two-dimensional materials under ion irradiation from atomistic simulations: the substrate is crucial — •Silvan Kretschmer¹, Mikhail Maslov^1,2, Sadegh Ghaderzadeh¹, Mahdi Ghorbani-Asl¹, Gregor Hlawacek¹, and Arkady V. Krasheninnikov^1,3 — ¹Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany — ²Moscow Institute of Physics and Technology, Dolgoprudny, Russia — ³Department of Applied Physics, Aalto University School of Science, Aalto, Finland

The response of two-dimensional (2D) materials to ion irradiation is interesting from a fundamental point of view – understanding the damage mechanism in a system with reduced dimensionality – as well as for potential applications e.g. device engineering. In this context, the Helium ion microscope (HIM) offers not only high-resolution images of the sample, but is also a valuable tool to pattern and change the morphology of 2D materials. In HIM the experimentalists usually deal with supported 2D materials, while atomistic computer simulations [1,2], which provide lots of insight into defect production, have been carried out only for suspended materials. The role of the substrate under the impact of energetic ions has not yet been addressed. Here, we use molecular dynamic simulations combined with a Monte Carlo method to investigate effects of ion irradiation on single layer MoS₂ supported by SiO₂ substrate. Depending on the ion energy and ion type the main damage mechanisms can be characterized as direct sputtering by the impacting ion or indirect sputtering, which originates from backscattered ions and sputtered substrate atoms. Specifically for typical HIM energies, we show that indirect sputtering dominates the direct sputtering, so that the model of free-standing material cannot be used.

[1] M. Ghorbani-Asl, S. Kretschmer, D. E. Spearot, and A. V. Krasheninnikov. Two-dimensional MoS₂ under ion irradiation: from controlled defect production to electronic structure engineering. 2D Materials 4, 025078, 2017

[2] L. Ma, Y. Tan, M. Ghorbani-Asl, R. Boettger, S. Kretschmer, S. Zhou, Z. Huang, A. V. Krasheninnikov, and F. Chen. Tailoring the optical properties of atomically-thin WS₂ via ion irradiation. Nanoscale 9, p. 10969-11340, 2017