Elementary processes in nanowire growth.

We propose that many of the complex morpho-logical phenomena observed during nanowire growth arise from the interplay of just three elementary processes: facet growth, droplet statics, and the introduction of new facets. We incorporate these processes into an explicit model for the vapor-liquid-solid growth of fully faceted nanowires. In numerical simulations with this model, different conditions can lead to either growth of a free-standing wire or lateral growth where the catalyst droplet crawls along the surface. An external perturbation can cause the wire to kink into a different direction. Different growth conditions can also change the shape of the growth tip. All of these phenomena have been observed, and the model behavior is consistent with the experimental observations.