Color imaging reveals graphene defects

PORTLAND, Ore. -- Pure sheets of graphene promise to run cooler yet faster than today's silicon chips. Unfortunately defect-free graphene sheets are extremely difficult to grow and even harder to characterize for defects

Cornell University researchers claim to have invented an imaging technique that simplifies their metrology by coloring graphene sheets to quickly identify their properties.

The new technique distinguishes the areas of graphene sheets which are true monolayers by colorizing the edges of perfect patches. Using diffraction imaging electron microscopy, the technique measures the angles at which electrons bounce off the sheets' surface, using different colors to identify them. The result is a colorized image of the sheets that can quickly identify grain boundaries according to their orientation.

The resulting images look like patchwork quilts with the large solid areas representing perfect monolayer patches, the colored edges representing imperfect boundaries between  the patches.

Funding for the graphene research was provided by the National Science Foundation through the Cornell Center for Materials Research and the Nanoscale Science and Engineering Initiative.