Temperature dependence of the thermal conductivity of thin silicon nanowires

ORAL

Abstract

We report extensive atomistic simulations aimed at understanding the variation of the lattice thermal conductivity of silicon nanowires as a function of temperature (T). We consider the range between 150 and 600 K, where experimental results are available. We find that the thermal conductivity of crystalline wires is of the same order of magnitude as that of the bulk and decreases as 1/T at high temperature. In wires with amorphous surfaces, the thermal conductivity may reach values close to that of amorphous silicon, and it is nearly constant in the temperature range examined here. The low value of kappa in core-shell wires, and its apparently anomalous behavior as a function of T, are determined by the presence of a large majority of diffusive, non-propagating modes in the vibrational spectrum. A parameter free model is presented that accounts for the T dependence observed in crystalline and core-shell systems, and provides a qualitative explanation of recent experiments.

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Authors

  • Davide Donadio

    Dept. Chemistry, UC Davis, Dept. of Chemistry, UC Davis, Department of Chemistry, UC Davis, USA

  • Giulia Galli

    Dept. of Chemistry and Dept. of Physics, UC Davis, Department of Chemistry and Department of Physics, University of California Davis, Dept of Chemistry \& Dept Physics, UC Davis, Department of Chemistry and Department of Physics, UC Davis, USA, Department of Chemistry and Department of Physics, University of California, Davis, UC Davis, Department of Chemistry, University of California, Davis, USA, University of California, Davis, Department of Chemistry and Department of Physics, University of California, Davis, CA, 95616, Department of Chemistry and Department of Physics, University of California, Davis, CA 95616, Chemistry Department and Physics Department UC Davis, Davis CA