Direct Imaging of Lattice Atoms and Topological Defects in Graphene Membranes

TLDR

The study investigates one‑atom‑thick crystalline graphene membranes by transmission electron microscopy. Using aberration‑correction with a monochromator, 1‑Å resolution is achieved at 80 kV, a low voltage essential for membrane stability. Every carbon atom is resolved, revealing a highly crystalline lattice with occasional point defects, including in‑situ observation of Stone‑Wales defect formation and annealing, and the exclusive appearance of five‑ and seven‑membered rings in defect combinations that avoid dislocations and disclinations, unlike on curved surfaces.

Abstract

We present a transmission electron microscopy investigation of graphene membranes, crystalline foils with a thickness of only 1 atom. By using aberration-correction in combination with a monochromator, 1-A resolution is achieved at an acceleration voltage of only 80 kV. The low voltage is crucial for the stability of these membranes. As a result, every individual carbon atom in the field of view is detected and resolved. We observe a highly crystalline lattice along with occasional point defects. The formation and annealing of Stone-Wales defects is observed in situ. Multiple five- and seven-membered rings appear exclusively in combinations that avoid dislocations and disclinations, in contrast to previous observations on highly curved (tube- or fullerene-like) graphene surfaces.