UC Berkeley

Graphene, an ideal two-dimensional membrane, has interesting electronic, optical, mechanical, and thermal properties originating from its unique one-atom-thick honeycomb-lattice structure. Reliable synthesis processes for large-area high-quality graphene have recently been developed, which opens up the capacity for many interesting applications. However, various synthesis-related structural inhomogeneities are still present in large-area graphene and have important implications on graphene's various properties.

Various transmission electron microscopy (TEM) techniques are employed to study suspended graphene membranes at micrometer and atomic scales. Atomic-resolution TEM and electron diffraction analysis are utilized to perform structural investigations of graphene. Notably, various one-dimensional defective structures including grain boundaries and folds in graphene are studied.

On the other hand, the structural manipulation of graphene provides another way to tailor the graphene's properties. Various structural engineering approaches are pursued including fold control, artificial stacking, tearing, Joule heating, and nanomanipulation. The modification of related properties is investigated with electrical measurements, Raman spectroscopy, electron microscopy, and theoretical calculations.