An investigation into the structural features and thermal conductivity of silicon nanoparticles using molecular dynamics simulations

The structural features and thermal conductivity of silicon nanoparticles of diameter 2–12 nm are studied in a series of molecular dynamics simulations based on the Stilling–Weber (SW) potential model. The results show that the cohesive energy of the particles increases monotonically with an increasing particle size and is independent of the temperature. It is found that particles with a diameter of 2 nm have a heavily reconstructed geometry which generates lattice imperfections. The thermal conductivity of the nanoscale silicon particles increases linearly with their diameter and is two orders of magnitude lower than that of bulk silicon. The low thermal conductivity of the smallest nanoparticles is thought to be the result of particle boundary and lattice imperfections produced during fabrication, which reduce the phonon mean free path (MFP). Finally, it is found that the influence of the temperature on the thermal conductivity decreases significantly as the temperature increases. Again, this is thought to be the result of a reduced phonon MFP at elevated temperatures.