Transport in graphene nanostructures with spatially modulated gap and potential

• Resonant-peak positions do not depend on the number of barriers at certain conditions.
• Gapped fractions cause decrease (increase) of the conductance (Fano factor).
• Gapped-graphene regions affect the Fano factor stronger than the conductivity.

We study transport properties of graphene nanostructures consisted of alternating slabs of gapless (Δ=0)(Δ=0) and gapped (Δ≠0)(Δ≠0) graphene in the presence of piecewise constant external potential equal to zero in the gapless regions. The transmission through single-, double-barrier structures and superlattices has been studied. It was revealed that any n-barrier structure is perfectly transparent at certain conditions defining the positions of new Dirac points created in the superlattice. The conductance and the shot noise were as well computed and investigated for the considered graphene systems. In a general case, the existence of gapped graphene fraction leads to a decrease of the conductance and an increase of the Fano factor. For two barriers formed by gapped graphene and separated by a long and highly doped region the Fano factor rises up to 0.5 in contrast to a similar gapless structure where the Fano factor is close to 0.25. Similar to a gapless graphene superlattice, creation of each new Dirac point manifests itself as a conductivity resonance and a narrow dip in the Fano factor. However, gapped graphene inclusion into the potential-barrier regions in the superlattice leads to more complicated dependence of the Fano factor on the potential height compared to pseudo-diffusive behavior (with F=1/3) typical for a gapless superlattice.