Zigzag faceting and width refinement of graphene nanoribbons and nanoperforations via catalyzed edge-annealing on Cu(111)

Top-down subtractive lithography has previously been used to pattern graphene nanostructures which lack ideal properties due to (1) limited resolution and (2) disordered edges. Here, we introduce a method to convert such disordered edges into relatively smooth zigzag edges via annealing on a Cu(111) substrate at ~950°C. The Cu catalyzes the re-arrangement of graphene edge atoms to energetically favorable sites, inducing zigzag edge faceting. The dimensions of the graphene nanostructures can be increased, decreased, or held constant during the annealing by tuning the relative balance between growth and etching reactions, described by a fundamental growth rate equation. To demonstrate the flexibility of this method, we lithographically pattern graphene nanoribbons with zigzag or armchair orientations, or alternatively perforate graphene with circular holes, and then anneal these nanostructures to realize zigzag edge termination in each case, with nanostructure feature size tailored from 8 to 80nm. The annealed nanostructures have smoother zigzag edges (~40% reduction in 1σ line edge roughness), and Raman spectroscopy confirms that they have lower edge disorder than top-down patterned samples. •Rough graphene edges are converted to smooth zigzag edges via “edge-annealing”.•Graphene nanostructure feature size can be increased, decreased, or held constant by tuning the balance between growth and etching reactions.•Cu catalyst lowers the kinetic barrier enabling edge-annealing at 950 °C.•Smooth edges have ~0.2 nm line edge roughness with a lower defect concentration density than top-down patterning.