Nanoscale Thermal Transport in Graphene Interfaces

We have investigated nanoscale thermal transport in epitaxial graphene systems using first-principles calculations and the Landauer formalism for phonon transport. Two types of interfaces are investigated: graphene-dielectric and graphene-metal heterojunctions. Hexagonal boron nitride (h-BN), SiC and SiC with hydrogen passivation (SiC-H) are studied as potential dielectric substrate materials for graphene devices. As for graphene-metal contacts, we have considered Au and Ti as prototypical systems for physisorbed and chemisorbed metal contacts, respectively. The interfacial thermal resistances of h-BN/G system is 5.3 10$^{-9}$ Km$^{2}$/W at room temperature, which is approximately one order of magnitude smaller than that of SiC/G system (55-79 10$^{-9}$ Km$^{2}$/W). Further analysis shows that heat conduction at the graphene interfaces is dominated by low-lying acoustic phonons and the thermal resistances strongly depend on atomic details at the interface such as lattice mismatch, disorder and surface reconstruction. Our work demonstrates the importance of developing a microscopic description of phonon dynamics at heterogeneous interfaces to engineer and design devices with optimal thermal management.