Plasma-graphene interaction and its effects on nanoscale patterning

A Harpale and M Panesi and HB Chew, PHYSICAL REVIEW B, 93, 035416 (2016).

DOI: 10.1103/PhysRevB.93.035416

Scalable and precise nanopatterning of graphene is an essential step for graphene-based device fabrication. Hydrogen-plasma reactions have been shown to narrow graphene only from the edges, or to selectively produce circular or hexagonal holes in the basal plane of graphene, but the underlying plasma-graphene chemistry is unknown. Here, we study the hydrogen-plasma etching of monolayer graphene supported on SiO2 substrates across the range of plasma ion energies using scale-bridging molecular dynamics (MD) simulations based on reactive force-field potential. Our results uncover distinct etching mechanisms, operative within narrow ion energy windows, which fully explain the differing plasma-graphene reactions observed experimentally. Specific ion energy ranges are demonstrated for stable isotropic (similar to 2 eV) versus anisotropic hole growth (similar to 20-30 eV) within the basal plane of graphene, as well as for pure edge etching of graphene (similar to 1 eV). Understanding the complex plasma-graphene chemistry opens up a means for controlled patterning of graphene nanostructures.

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