Isotope doping-induced crossover shift in the thermal conductivity of thin silicon nanowires

ZY Zhou and K Xu and ZX Song and Z Wang and YW Lin and Q Shi and YC Hao and YQ Fu and ZS Zhang and JY Wu, JOURNAL OF PHYSICS-CONDENSED MATTER, 35, 085702 (2023).

DOI: 10.1088/1361-648X/acab4a

Here, using homogeneous nonequilibrium molecular dynamics simulations, we report the thermal transport characteristics of thin Si nanowires (NWs) with varying size and isotope doping ratio. It is identified that crossover in the thermal conductivity (kappa) of both isotope doping- free and isotope doped Si-NWs appears at critical sizes, below which kappa is enlarged with decreasing size because the hydrodynamic phonon flow predominates, above which, due to the dominant phonon boundary scattering, opposite behavior is observed. With increasing isotope doping, however, the critical size in minimizing the kappa is moved to small values because the phonon impurity scattering caused by isotope doping is critically involved. Moreover, there is a critical isotope doping (<50%) in the critical size motion, originating from that, above which, the critical size no longer moves due to the persistence of hydrodynamic phonon flow. This study provides new insights into the thermal transport behaviors of quasi-1D structures.

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