Shadowing growth of three-dimensional nanostructures on finite size seeds

Abstract

We reported the fabrication of silicon (Si) nanorods and springs on arrays of seeds with different diameters by using glancing angle deposition technique. Single nanorod is possible to grow on individual seeds if the size of the seeds is small enough. On large size seeds, however, multiple Si nanorods are observed in experiments. The effects of the size of seeds were studied by using Monte Carlo simulations based on a ballistic aggregation model. The simulation model also includes ballistic sticking, shadowing, and surface mobility. Both of the top-view and cross-sectional images of the nanostructures were generated in simulation and compared to the images of experimental samples taken by scanning electron microscopy. We also investigated the effect of surface diffusion on the formation of nanostructures. In our experiments, no separate rods formed when the surface mobility is sufficiently high, such as the deposition of cobalt on the large size seeds.