Single-atom-thick graphene sheets can be produced at metre scales, bringing large-area applications in electronics and photovoltaics closer. However, such large pieces can be expected to be polycrystalline, so that it is important to determine the nature and size of grains in large-area graphene. This paper uses a combination of old and new transmission electron microscope techniques to carry out atomic-resolution imaging at grain boundaries as well as mapping of the location, orientation and shape of several hundred grains and boundaries with diffraction-filtered imaging. By correlating grain imaging with scanned probe and transport measurements, it is shown that the grain boundaries dramatically weaken the mechanical strength of graphene membranes, but do not as dramatically alter their electrical properties.
- Pinshane Y. Huang
- Carlos S. Ruiz-Vargas
- David A. Muller
