▎ 摘　　要

Single-step nano-lithography was performed on graphene sheets using a helium ion microscope. Parallel "defect" lines of similar to 1 mu m length and approximate to 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 similar to 2x smaller than do Ga ions, demonstrating that scanning-He+-beam lithography can texture graphene with less damage. (C) 2014 AIP Publishing LLC.