Thermal properties of thin films made from MoS₂ nanoflakes and probed via statistical optothermal Raman method

A deep understanding of the thermal properties of 2D materials is crucial to their implementation in electronic and optoelectronic devices. In this study, we investigated the macroscopic in-plane thermal conductivity (κ) and thermal interface conductance (g) of large-area (mm²) thin film made from MoS₂ nanoflakes via liquid exfoliation and deposited on Si/SiO₂ substrate. We found κ and g to be 1.5 W/mK and 0.23 MW/m²K, respectively. These values are much lower than those of single flakes. This difference shows the effects of interconnections between individual flakes on macroscopic thin film parameters. The properties of a Gaussian laser beam and statistical optothermal Raman mapping were used to obtain sample parameters and significantly improve measurement accuracy. This work demonstrates how to address crucial stability issues in light-sensitive materials and can be used to understand heat management in MoS₂ and other 2D flake-based thin films.