Interplay of Phonon Scattering and Interfacial Coupling in Thermal Transport of MoTe₂

Understanding and engineering thermal transport in two dimensional (2D) materials is pivotal for the thermal management of next-generation high-power electronics. Among transition metal dichalcogenides (TMDCs), molybdenum ditelluride (MoTe₂) stands out as a promising candidate for various electronic applications. However, its thermal transport properties remain insufficiently understood. Herein, an investigation of both intrinsic and substrate-modulated thermal conductivity in MoTe₂ is performed, using non-contact optothermal Raman spectroscopy and high-resolution scanning thermal microscopy. The intrinsic thermal conductivities of suspended monolayer and double-layer MoTe₂ are 23.3 ± 1.5 and 17.5 ± 1.8 W m^-1 K^-1, respectively. A pronounced substrate-induced modulation of thermal transport is also observed: monolayer MoTe₂ on h-BN exhibits significantly enhanced thermal conductivity of 11.6 ± 0.2 W m^-1 K^-1, while counterparts supported on SiO₂/Si show lower values ≈7.4 ± 0.2 W m^-1 K^-1. More importantly, a non-monotonic thickness dependence is identified in supported configurations. These results are likely contributed by the contrasting thermal conductivities of the substrates, along with the interplay of interlayer coupling, interfacial phonon scattering, and symmetry-related phonon mode suppression. Overall, the findings not only uncover a critical thickness threshold for effective substrate coupling but also provide insights into thermal transport tuning via substrate engineering.