Detecting the phonon interference effect in Si/Ge nanocomposite by wave packets

As the particle size in nanocomposites approaches the order of several nanometers that is comparable with the phonon wavelength, the phonon wave interference and particle scattering effect will lead to a much more complicated energy transport. This letter reports the investigation of phonon interference and scattering in Si/Ge nanocomposites by the phonon wave packet simulation. The particle size, particle layer number, and particle shape effects on the phonon transmission are considered. For both cubic and spherical particles, the phonon transmission coefficient fluctuates obviously with the increasing particle size and there are local peaks and valleys of transmission coefficient at certain particle sizes. The transmission decreases with the increasing layers of particle. The optical multi-layer transmission model can be applied to predict the transmission coefficient of Si/Ge nanocomposites with layered particles. The enhancement of thermal conductance is up to 19.1% due to the phonon interference effect. (C) 2015 AIP Publishing LLC.