First STM spectroscopy of graphene flakes yields new surprises

Under the STM tip a flake of graphene 50 microns (millionths of a meter) long rests on a substrate of silicon with a thin layer of silicon dioxide insulation (upper left). The graphene is contacted by gold electrodes, connected to outside experimental equipment and to the underlying silicon electrode, which is used to apply a gate voltage. At lower right, a topographical image of the graphene flake, 10 nanometers (billionths of a meter) across. Variations in height of one or two angstroms (ten-billionths of a meter) are likely caused by the roughness of the substrate. Credit: Lawrence Berkeley National Laboratory