Cross-plane thermal conductance of Au/graphene/Au heterojunction

Thermal management has become a critical issue for microelectronics, as the characteristic sizes of these devices shrink into the nanometer region. Interesting phenomena were observed for heat conduction through ultrathin interfacial layers, such as thickness dependent thermal boundary conductivity. Here, we use the Frequency Domain Thermoreflectance technique to investigate the heat conduction across the heterojunction composed of few-layer graphene as the interfacial layer between gold. By varying the graphene layer number to control the thickness of the interfacial layer, we measure the thickness dependent thermal conductance across this sandwiched structure. We found that electron transmission dominates the thermal conductance for monolayer graphene, and a two-orders of magnitude decrease in thermal conductance through bilayer graphene. For more layers graphene, phonon thermal conductivity is suggested to be the major contributor.