Speed Bumps Less Important Than Potholes for Graphene

Comparison of an STM topographic image of a section of graphene sheet (top left) with spectroscopy images of electron interference at three different energies shows strong interference patterns generated by atomic scale defects in the graphene crystal (red arrows) but only modest disturbances caused by larger scale bumps in the sheet (blue arrows.) Analysis of the ripples shows that the electron energy in graphene is inversely proportional to its wavelength, just like light waves. The area imaged is approximately 40 nanometers square. Credit: NIST/Georgia Tech