Heat Transport through van der Waals Atomic Layers

Atomically thin layered materials demonstrate unique potential for nanoscale thermal transport in two ways: 1) they possess anisotropic transport characteristics and 2) they can be vertically stacked to generate artificial films with novel interlayer transport properties. We present the thermal conductivities of artificially-stacked MoS₂ films measured in the temperature range of 77–350 K using time-domain thermoreflectance. These films are generated by the layer-by-layer assembly of large-area MoS₂ monolayer films in vacuum with precisely controlled film thickness and pristine interlayer interfaces. One unique property of our stacked films is the layer misalignment, which is expected to considerably suppress the out-of-plane thermal conductivities compared to those measured from exfoliated single crystal MoS₂. The integration of atomically thin films into electronic devices will boost current heat management technologies via the realization of electron-transmitting, phonon-blocking material systems, opening up new possibilities in thermoelectrics.