Direct nanoscale imaging of ballistic and diffusive thermal transport in graphene nanostructures

O.V. Kolosov, M.E. Pumarol, P. Tovee, M.C. Rosamond, M.C. Petty, D.A. Zeze, V. Falko
Lancaster University, UK

Keywords: graphene, heat transport, phonons, ballistic phonons, thermal conductivity, scanning thermal microscopy, nanoscale

Summary:

We report direct imaging of thermal transport in single and few-layer graphene with approximately 50 nm lateral resolution using high vacuum scanning thermal microscopy. Images reveal low thermal resistance of areas of suspended graphene where heat is conducted by ballistic phonons and suppressed heat transport in adjacent areas of supported graphene. A nano-thermal imaging of boundary between supported graphene layers of different thickness indicated that the mean-free-path of thermal phonons is below 100 nm.