A Nonequilibrium Molecular Dynamics Study of In-Plane Thermal Conductivity of Silicon Thin Films

We employed a nonequilibrium molecular dynamics (NEMD) simulator to calculate the in-plane thermal conductivity of silicon thin films. To avoid contamination of the temperature nonlinearity due to artificial heat addition/rejection, the selection of a proper linear range was investigated. It was found that the contaminated range was larger for thicker films and longer simulation lengths. To perform the quantum correction that is necessary when the MD simulation temperature is lower than the Debye temperature, we also attempted to obtain the confined phonon densities of states via equilibrium MD (EMD) simulations. The investigation showed that the thermal conductivities corrected by the thin-film density of states (DOS) agree excellently with theoretical predictions based on the phonon Boltzmann transport equation. A relationship between the surface roughness measurable in the laboratory and the specular fraction usually employed in the analysis was thus constructed.