HEAT TRANSPORT BY PHONONS AND ELECTRONS ACROSS GRAPHENE INTERFACES AND GRAPHENE-BASED NANOSTRUCTURES

Abstract

Due to high in-plane thermal conductivity of graphene, heat dissipation in graphene devices is primarily governed by the thermal resistance of metal/graphene interface. First, we compared the thermal conductance (<I>G</I>) of Al/trG/Cu and Al/grG/Cu to investigation which of the following factors: roughness, residues, oxides, conformity and voids could reduce the <I>G</I> of graphene interfaces. Second, we measured the <I>G</I> of Al/trG/Cu, Al/grG/Cu, Au/trG/Au, Ag/trG/Ag, and Pd/trG/Pd, and demonstrated that electrons do not play a crucial role in heat transfer across graphene interfaces, regardless of whether the metals are physisorbed or chemisorbed. We also demonstrate a convenient approach to enhance electronic heat transfer across metal/graphene interfaces by depositing the top Pd layer of Pd/trG/Pd interfaces using rf magnetron sputtering. Finally, we prepared metal/graphene heterostructures with the ratio of phononic and electronic thermal conductivity Λ<SUB>ph</SUB> / Λ<SUB>e</SUB> ≈1 at room temperature, despite the ultralow thermal conductivity of ≈0.1 W m<SUP>-1</SUP> K<SUP>-1</SUP>.