We investigate graphene superlattices of nitrogen and boron substitutional
defects and by using symmetry arguments and electronic structure calculations
we show how such superlattices can be used to modify graphene band structure.
Specifically, depending on the superlattice symmetry, the structures considered
here can either preserve the Dirac cones (D_{6h} superlattices) or open a band
gap (D_{3h}). Relevant band parameters (carriers effective masses, group
velocities and gaps, when present) are found to depend on the superlattice
constant n as 1/n^{p} where p is in the range 1-2, depending on the case
considered. Overall, the results presented here show how one can tune the
graphene band structure to a great extent by modifying few superlattice
parameters.Comment: accepted, J. Phys. Chem.