Enhanced thermal transport across monolayer MoS₂

Characterizing the thermal properties of MoS₂ is important for the design of electronic devices based on this material. We used frequency domain thermoreflectance to study the cross-plane thermal transport in mechanically exfoliated MoS₂ samples supported on SiO₂ and muscovite mica substrates. The thickness of MoS₂ ranged between one and five layers, and the MoS₂ layers were sandwiched between a metal layer and the substrate. In the case of mica, heat transport into the substrate remained the same whether or not a monolayer of MoS₂ was present, whereas, for SiO₂, heat transport was reduced by surface roughness. We observed a significant improvement in heat transport across monolayer MoS₂ as compared to few layer MoS₂. For MoS₂ on SiO₂, the effective thermal interface conductance was improved by more than three times if a monolayer was used. For MoS₂ on mica, the thermal interface conductance was approximately two times better for monolayer MoS₂. This implies that monolayer MoS₂ has superior thermal properties and can be used in electronic devices as an intermediate layer between two materials. Additionally, we also report on the measurement of anisotropic thermal conductivity in bulk MoS₂ and mica.