Graphene nanoribbon superlattices fabricated via He ion lithography

Abstract

Single-step nano-lithography was performed on graphene sheets using a helium ion microscope. Parallel “defect” lines of ∼1 μm length and ≈5 nm width were written to form nanoribbon gratings down to 20 nm pitch. Polarized Raman spectroscopy shows that crystallographic orientation of the nanoribbons was partially maintained at their lateral edges, indicating a high-fidelity lithography process. Furthermore, Raman analysis of large exposure areas with different ion doses reveals that He ions produce point defects with radii ∼ 2× smaller than do Ga ions, demonstrating that scanning-He+-beam lithography can texture graphene with less damage.

Tunable graphene phononic crystal

“…Overall, we can tune the resonance frequency of the defect mode by more than 350% and access new regimes of strain engineering. 43 , whilst causing little damage to suspended graphene 44,45 .…”

Revealing lattice disorder, oxygen incorporation and pore formation in laser induced two-photon oxidized graphene

“…As the most studied 2D material, graphene is a platform to unravel the science behind low dimensional materials. Therefore, many methods have already been used to modify graphene, including different strategies for tailoring its shape [5][6][7][8], defect control [9][10][11], chemical modification [12][13][14][15], besides many others. Recently, an all-optical method, namely, two-photon oxidation of graphene was demonstrated, which proved to have some advantages as compared to other oxidation methods, including direct writing of device features with sub-micrometer resolution, high speed and controlled level of oxidation [16][17][18][19].…”

Imaging of carbon nanomembranes with helium ion microscopy

“…There is scarce literature on HIM imaging of ultrathin membranes. Many researchers have examined graphene, where the main focus was on the modification and production of small structures and circuits [18][19][20][21][22]. The thickness of graphene is comparable to CNMs, but a fundamental difference is its high conductivity, which eases charged particle imaging.…”