Atomistic-scale simulation of the thinning process of multilayer graphene with low-energy helium plasma

M Hatami and AR Niknam, PHYSICS OF PLASMAS, 32, 053901 (2025).

DOI: 10.1063/5.0259818

The graphene thinning by low-energy helium plasma etching offers a nonrandom method with precise control over the number of layers. This study uses molecular dynamics simulations to investigate the etching process of multilayer graphene (MLG) under low-energy (<= 1 keV) He+ irradiation. It is shown that low-energy He+ ions induce layer-by-layer thinning without creating deep pits or reducing the lateral dimensions of graphene. It is observed that increasing the energy of the He+ ion enhances the etching rate. The thinning process from 4L to 3L-graphene has an etching rate comparable to 4L to 1L-graphene, indicating consistency regardless of the thickness of MLG. During the thinning process before the complete removal of one layer, interlayer distance expands, and the interlayer expansion increases with He+ ion density until it reaches saturation. The saturation value of interlayer expansion decreases with higher ion energy, occurring at a lower He+ ion density. (c) 2025 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/4.0/).

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