Unexpected slip mechanism induced by the reduced dimensions in silicon nanostructures: Atomistic study

We have performed molecular dynamics simulations and first-principles calculations to investigate the first stages of plasticity in single-crystalline silicon nanostructures free of initial defects, under compressive and tensile strain along the [0 0 1] axis. In compression especially, we observe the activation of {0 1 1} planes, both in nanowires and in thin films, regardless of the temperature and the interatomic potential used. The occurrence of such an unexpected slip system can be explained by a careful investigation of the generalized stacking fault energy under different stress conditions, and the associated restoring forces. Finally, the activation of the {0 1 1} planes is shown to be an indirect consequence of the small dimensions of the nanostructures considered.