Wide frequency phonons manipulation in Si nanowire by introducing nanopillars and nanoparticles

The combination of different nanostructures can hinder phonons transmission in a wide frequency range and further reduce the thermal conductivity (TC). This will benefit the improvement and application of thermoelectric conversion, insulating materials and thermal barrier coatings, etc. In this work, the effects of nanopillars and Ge nanoparticles (GNPs) on the thermal transport of Si nanowire (SN) are investigated by nonequilibrium molecular dynamics (NEMD) simulation. By analyzing phonons transport behaviors, it is confirmed that the introduction of nanopillars leads to the occurrence of low-frequency phonons resonance, and nanoparticles enhance high-frequency phonons interface scattering and localization. The results show that phonons transport in the whole frequency range can be strongly hindered by the simultaneous introduction of nanopillars and nanoparticles. In addition, the effects of system length, temperature, sizes and numbers of nanoparticles on the TC are investigated. Our work provides useful insights into the effective regulation of the TC of nanomaterials.