  We employ scanning probe microscopy to reveal atomic structures and nanoscale
morphology of graphene-based electronic devices (i.e. a graphene sheet
supported by an insulating silicon dioxide substrate) for the first time.
Atomic resolution STM images reveal the presence of a strong spatially
dependent perturbation, which breaks the hexagonal lattice symmetry of the
graphitic lattice. Structural corrugations of the graphene sheet partially
conform to the underlying silicon oxide substrate. These effects are obscured
or modified on graphene devices processed with normal lithographic methods, as
they are covered with a layer of photoresist residue. We enable our experiments
by a novel cleaning process to produce atomically-clean graphene sheets.
