  We have demonstrated that the island nucleation in the initial stage of
epitaxial thin film growth can be tuned by substrate surface charge doping.
This charge effect was investigated using spin density functional theory
calculation in Fe-deposition on graphene substrate as an example. It was found
that hole-doping can apparently increase both Fe-adatom diffusion barrier and
Fe inter-adatom repulsion energy occurring at intermediate separation, whereas
electron-doping can decrease Fe-adatom diffusion barrier but only slightly
modify inter-adatom repulsion energy. Further kinetic Monte Carlo simulation
showed that the nucleation island density can be increased up to ten times
larger under hole-doping and can be decreased down to ten times smaller than
that without doping. Our findings indicates a new route to tailoring the growth
morphology of magnetic metal nanostructure for spintronics applications via
surface charge doping.
