Vibrational mean free paths and thermal conductivity of amorphous silicon from non-equilibrium molecular dynamics simulations

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2016-12-01
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en
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AIP ADVANCES, Volume 6, issue 12
Abstract
The frequency-dependent mean free paths (MFPs) of vibrational heat carriers in amorphous silicon are predicted from the length dependence of the spectrally decomposed heat current (SDHC) obtained from non-equilibrium molecular dynamics simulations. The results suggest a (frequency)−2 scaling of the room-temperature MFPs below 5 THz. The MFPs exhibit a local maximum at a frequency of 8 THz and fall below 1 nm at frequencies greater than 10 THz, indicating localized vibrations. The MFPs extracted from sub-10 nm system-size simulations are used to predict the length-dependence of thermal conductivity up to system sizes of 100 nm and good agreement is found with independent molecular dynamics simulations. Weighting the SDHC by the frequency-dependent quantum occupation function provides a simple and convenient method to account for quantum statistics and provides reasonable agreement with the experimentally-measured trend and magnitude.
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Sääskilahti , K , Oksanen , J , Tulkki , J , McGaughey , A J H & Volz , S 2016 , ' Vibrational mean free paths and thermal conductivity of amorphous silicon from non-equilibrium molecular dynamics simulations ' , AIP Advances , vol. 6 , no. 12 , 121904 . https://doi.org/10.1063/1.4968617