Nonequilibrium molecular dynamics simulation for size effects on thermal conductivity of Si nanostructures

The thermal conductivity of Si nanostructres is investigated using nonequilibrium molecular dynamics (NEMD) simulation based on the Tersoff III inter-atomic potential. A reliable range of heat flux for the calculation of thermal conductivity is determined by the comparative study of NEMD simulations with different heat fluxes. The remarkable dependence of thermal conductivity on the length of nanostructures is observed. It is also found that the thermal conductivity is less sensitive to the cross-section area perpendicular to the heat flux than to the length of Si nanostructures. Based on the relationship between the thermal conductivity and the nanostructure length, the thermal conductivity and the phonon mean-free path of the infinite bulk Si system are extrapolated.