First-principles study of the transport properties of graphene-hexagonal boron nitride superlattice

Hexagonal boron nitride (hBN) is a promising material to be integrated with graphene for high-performance graphene based electronics. We investigate the electronic, thermal, and thermoelectric transport properties of graphene-hexagonal boron nitride (G-hBN) superlattice by using the first-principles density functional calculations combined with the non-equilibrium Green's function formalism. The results show that a gap of 0.2 eV is opened in the band structure of the G-hBN superlattice due to the sublattice symmetry broken, the conductance and corresponding electron thermal conductance are both reduced. The phonon thermal conductance is also reduced due to the interlayer interactions, which linearize the flexural phonon modes and reduce the corresponding phonon density of states. Compared with those of graphene, though the electronic and phonon transport are both reduced, while the Seebeck coefficient is greatly enhanced. Finally, the thermoelectric figure of merit ZT of the G-hBN superlattice is enhanced 44% that of graphene. Our findings provide instructional information for future applications of graphene in electronics design.