Highly in-plane anisotropy of thermal transport in suspended ternary chalcogenide Ta2NiS5

Energy dissipation has always been an attention-getting issue in modern electronics and the emerging low-symmetry two-dimensional (2D) materials are considered to have broad prospects in solving the energy dissipation problem. Herein the thermal transport of a typical 2D ternary chalcogenide Ta2NiS5 is investigated. For the first time we have observed strongly anisotropic inplane thermal conductivity towards armchair and zigzag axes of suspended few-layer Ta2NiS5 flakes through Raman thermometry. For 7-nm-thick Ta2NiS5 flakes, the kappa(zigzag) is 4.76 W.m(-1).K-1 and kappa(armchair) is 7.79 W.m(-1).K-1, with a large anisotropic ratio (kappa(armchair/)kappa(zigzag)) of 1.64 mainly ascribed to different phonon mean-free-paths along armchair and zigzag axes. Moreover, the thickness dependence of thermal anisotropy is also discussed. As the flake thickness increases, the kappa(armchair/)kappa(zigzag) reduces sharply from 1.64 to 1.07. This could be attributed to the diversity in phonon boundary scattering, which decreases faster in zigzag direction than in armchair direction. Such anisotropic property enables heat flow manipulation in Ta2NiS5 based devices to improve thermal management and device performance. Our work helps reveal the anisotropy physics of ternary transition metal chalcogenides, along with significant guidance to develop energy-efficient next generation nanodevices.