  Atomic-scale topography of epitaxial multilayer graphene grown on
4H-SiC(0001) was investigated using scanning tunneling microscopy (STM).
Bunched nano-ridges ten times smaller than previously recorded were observed
throughout the surface, the morphology of which was systematically altered
using a relatively new technique called electrostatic-manipulation scanning
tunneling microscopy. Transformed graphene formations sometimes spontaneously
returned to their original morphology, while others permanently changed. Using
an electrostatic model, we calculate that a force up to ~5 nN was exerted by
the STM tip, and an energy of around 10 eV was required to alter the geometry
of a ~100 X 200 nm^2 area.
