| The thermal conductivity of silicon thin films is predicted in the in-plane direction using equilibrium molecular dynamics, the Green-Kubo relation and the Stillinger-Weber interatomic potential. Bulk silicon thermal conductivity is predicted to validate the computational code, and assess the influence of the simulation domain size and the periodic boundary conditions on the thermal conductivity predictions. Our study shows that the predicted bulk silicon thermal conductivity is independent of the simulation domain size and the periodic boundary conditions, for domain sizes and temperatures investigated. Our analytical studies, based on the Boltzmann transport equation, suggest that this non-dependency is due to an increment of the phonon relaxation time. A repulsive potential for the numerical treatment of the silicon film surfaces is propose and validate. We verify that equilibrium molecular dynamics simulations using this repulsive potential conserve energy, number of atoms and volume. Therefore, the repulsive potential strategy is suitable for the prediction of in-plane thermal conductivity of thin films using the Green-Kubo formalism. The predicted in-plane thermal conductivity follows the trend reported experimentally at 300 K, the magnitude of the thermal conductivity decreases as the film thickness decreases. This trend is also observed at 1000 K. In addition, the atomistic system captures the reduction of the phonon mean free path with temperature, since smaller film thickness are required to predict bulk thermal conductivity values at 1000 K than at 376 K. The predictions also show good agreement between the predicted thermal conductivity for thick films and the available experimental data for bulk silicon. |
