  Nanoscience offers a unique opportunity to design modern materials from the
bottom up, via low-cost, solution processed assembly of nanoscale building
blocks. These systems promise electronic band structure engineering using not
only the nanoscale structural modulation, but also the mesoscale spatial
patterning, although experimental realization of the latter has been
challenging. Here we design and fabricate a new type of artificial solid by
stacking graphene on a self-assembled, nearly periodic array of nanospheres,
and experimentally observe superlattice miniband effects. We find conductance
dips at commensurate fillings of charge carriers per superlattice unit cell,
which are key features of minibands that are induced by the quasi-periodic
deformation of the graphene lattice. These dips become stronger when the
lattice strain is larger. Using a tight-binding model, we simulate the effect
of lattice deformation as a parameter affecting the inter-atomic hopping
integral, and confirm the superlattice transport behavior. This 2D
material-nanoparticle heterostructure enables facile band structure engineering
via self-assembly, promising for large area electronics and optoelectronics
applications.
