Mechanism of surface-guided nanowire growth

Nanowires (NWs) are one of the future building blocks for nanotechnology-based applications owing to their unique properties. Catalyzed surface-guided NWs, which are aligned via epitaxial or graphoepitaxial relations with the substrate, are highly attractive owing to the possibility of controlling their position, direction, and crystallographic orientation. To adequately control these features and gain predictive abilities, a deeper understanding of the growth mechanism of surface-guided NWs is required. Here, we experimentally study the kinetics of planar catalyzed NWs for the first time. Our model considers two main regimes of the growth rate of NWs depending on their thickness: the Gibbs–Thompson regime, which dominates the growth of thinner NWs, and the surface-diffusion-induced regime, which dominates the growth of thicker ones. By developing this kinetic model and fitting it to the experimental kinetic data, we determine the dimensionality of the surface diffusion. We observe a good correlation between the model and the results for surface-guided ZnSe and ZnS NWs grown on c-plane sapphire. The new developed model distinguishes between the growth mechanisms of vertical and horizontal NWs, underscores the important role of the substrate in the horizontal growth, and provides new insights into the mechanism of surface-guided NWs growth.