Quantitative assessment of thermal resistance in graphene field-effect transistors based on a phonon hydrodynamics and van der Waals coupling approach

In the progressive miniaturization of graphene field-effect transistors (GrFETs), pronounced thermal boundary resistance (TBR) and increasing ballistic-diffusive thermal resistance pose formidable challenges to thermal management. Quantitative analysis of thermal resistance is crucial for advancing efficient thermal designs in GrFETs using state-of-the-art technology. The inherently low-dimensional structure nature of graphene means that thermal conduction in GrFETs, governed by phonon hydrodynamic transport and van der Waals (vdW) interactions, cannot be accurately described by traditional Fourier's law-based models or the single-mode relaxation time approximation. This study introduces an innovative thermal simulation framework that addresses these challenges by incorporating phonon hydrodynamics equations and considering weak vdW coupling. Our findings indicate that thermal conduction in GrFETs is predominantly facilitated by flexural (ZA) phonons, and their thermal transport efficiency is significantly influenced by substrate perturbations. Specifically, the TBR in GrFETs is closely associated with the weak vdW coupling between ZA phonons and substrate atoms. Furthermore, this study employs dimensionless thermal resistance ratios and Knudsen numbers to explore the impact of silicon's geometric dimensions, heat source size, and ballistic phenomena on the substrate's thermal resistance. These insights provide substantial theoretical support for the development of efficient thermal management strategies in GrFETs.