  The burgeoning field of atomic level material control holds great promise for
future breakthroughs in quantum and memristive device manufacture and
fundamental studies of atomic-scale chemistry. Realization of atom-by atom
control of matter represents a complex and ongoing challenge. Here, we explore
the feasibility of controllable motion of dopant Si atoms at the edges of
graphene via the sub-atomically focused electron beam in a scanning
transmission electron microscope (STEM). We demonstrate that the graphene edges
can be cleaned of Si atoms and then subsequently replenished from nearby source
material. It is also shown how Si edge atoms may be pushed from the edge of a
small hole into the bulk of the graphene lattice and from the bulk of the
lattice back to the edge. This is accomplished through sputtering of the edge
of the graphene lattice to bury or uncover Si dopant atoms. These experiments
form an initial step toward general atomic scale material control.
