Thermal Conductivity Characterization of TMD-Based van der Waals Heterostructures by Time- and Space-Resolved Raman Technique

Two-dimensional (2D) van der Waals (vdWs) heterostructures, typically formed by vertically stacking distinct 2D materials, have unique properties that cannot be observed in single materials. Such stacking enables precise modulation of electronic and optical characteristics, introducing advantages such as bandgap engineering and quantum confinement, which contribute to the high performance of devices. However, with the ongoing miniaturization of devices and the rise in integration density, efficient heat dissipation has emerged as a critical challenge. This necessitates a systematic investigation of the thermal conductivity (κ) of both the heterostructures and their monolayer constituents. Currently, most studies focus on the thermal conductivity characterization of heterostructures rather than on the monolayers that formed the heterostructures. Considering that the out-of-plane phonons of single monolayers in a heterostructure may be suppressed due to the interaction between adjacent layers, which can have an impact on the thermal conductivity of monolayers. Hence, a time- and space-resolved Raman technique is proposed to measure the thermal conductivities of both monolayer transition metal dichalcogenide (TMD) materials and formed heterostructures. Numerical simulations provide insight into intrinsic thermal transport mechanisms, while experimental measurements under realistic conditions validate the feasibility of the proposed technique. All these studies provide a good foundation for the application of heterostructures in nanoelectronic devices.