Heat Transfer in Encased Graphene

Experimentally understanding the heat transfer in graphene (sheets of graphite a few atoms thick) is important for fundamental physics as well as device applications. In particular, measurements of the heat flow through graphene encased by oxide layers are essential for future graphene-based nanoelectronics, interconnects, and thermal management structures. Here we use a “heat spreader method” to study the heat dissipation performance of encased graphene. Measurements show enhanced heat spreading by a graphene layer as compared to control samples without graphene. At room temperature, the in-plane thermal conductivity of encased graphene sheets of thickness 2 nm and 5 nm is measured to be ∼150 W/m-K, more than one order of magnitude smaller than a published report for a freely-suspended graphene sheet [A. A. Balandin et al., Nano Lett. 8, 902], as well as bulk graphite. We also used a differential 3ω method to measure the thermal contact resistance between graphene and SiO2, finding a value around 10−8 m2-K/W at room temperature. Possible reasons for the unexpectedly low thermal conductivity are also discussed.