Thermal Conductivities of Suspended Graphene/MoS ₂ Van der Waals Heterostructures Measured by Raman Spectroscopy

Van der Waals' heterostructures of 2D materials have great potential in developing electronic and optoelectronic devices. Understanding heat transfer in these heterostructures is essential for effective thermal management. However, studying heat transfer in the few-atom-thick 2D heterostructure remains challenging. In this work, the first measurement of in-plane thermal conductivities of suspended graphene/MoS₂ heterostructures using optothermal Raman spectroscopy is reported. The thermal conductivity of the suspended graphene/MoS₂ heterostructure is extracted from the dependencies of the MoS₂ A_1g Raman peak frequency on temperature and excitation laser power. The average thermal conductivity of graphene/MoS₂ heterostructures at room temperature is found at 172 W m^-1 K^-1, which is 5.4 times higher than that of the suspended monolayer MoS₂ (32 ± 5 W m^-1 K^-1). This superior heat transfer in the graphene/MoS₂ heterostructure is attributed to the high thermal conductivity (700 ± 58 W m^-1 K^-1) of monolayer graphene prepared by chemical vapor deposition. This work not only demonstrates the measurement of in-plane thermal conductivities of van der Waals heterostructures of 2D materials but also shows the great potential of using monolayer graphene to significantly enhance heat dissipation in ultrathin materials.