The thermal transport properties of nanowires can be significantly influenced by the implementation of a core-shell structure, which introduces interface scattering and phonon localization effects, opening avenues for novel applications. In this paper, we use the method of non-equilibrium molecular dynamics to simulate the effects of system temperature, cross-sectional width, and nanopillar inter-face on the thermal transport of GaN/Si3N4 core-shell nanowires. The thermal transport process ofphonons in core-shell nanowires is studied by calculating the vibrational density of states, phonon participation rate and dispersion curve. The results show that the core-shell nanowires characterized by smooth interfaces exhibit a 17.4% decrease in thermal conductivity at room temperature when contrasted with pristine GaN nanowires. In addition, the thermal conductivity of pristine GaN increases monotonically with the cross-sectional width, while the core-shell nanowires exhibit a phenomenon of initially decreasing and then increasing. The thermal conductivity of core-shell nanowires decreases by 23% due to the inclusion of nanopillars at the interface. The presence of nano-pillars increases phonon-surface scattering intensity at low frequency and modifies phonon dispersion to decrease the group velocity. The hybridization of phonon modes between those of the nanopillars and the Si3N4 shell gives rise to numerous dispersionless resonance phonon modes that span the entire phonon spectrum. These results suggest that controlling the long-wavelength phonon modes at the interface and leveraging the resonance of nanopillars can reduce the thermal conductivity of GaN/Si3N4 core-shell nanowires, so that the heat transfer can be effectively adjusted.
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