Droplets to Merged Nanostructures: Evolution of Gold Nanostructures by the Variation of Deposition Amount on Si(111)

We studied the evolution of Au nanostructures in dome-shaped Au droplets that merge into Au nanostructures on Si(111) by systematically controlling the Au deposition amount (DA) under a fixed annealing temperature and annealing duration. Even under identical growth conditions, the configuration, density, and size of Au nanostructures drastically vary depending on the amount of Au deposition in the range of 0.5-20 nm. Through systematic analysis of the resulting Au nanostructures in determining the average height, density, and surface area ratio, as well as the Fourier filter transform power spectrum and cross-sectional line profiles, we clearly demonstrate the evolution process of Au nanostructures and thus the control of the size, density, and configurations. The evolution of Au droplets on Si(111) with the increased DAs initially appears to be progressing based on the Volmer-Weber growth mode for the Au DAs up to 4 rim, but with further increased DAs up to 20 rim, it turns out that the growth occurs in the Frank-van der Merwe growth mode, resulting in a layer-by-layer growth. In addition, by the sharp comparison between preannealed samples and resulting Au nanostructures, we quantitatively present the evolution of Au nanostructures. This study can find applications in nanowire fabrication on Si(111).