Metal Nanodot Array via Thin Oil Layer-Assisted Dropwise Solid-State Dewetting.

Precise control of metal nanodot arrays is crucial for optimizing their plasmonic, catalytic, and photonic properties. Fabrication methods for homogeneous nanodots generally rely on complex processes, such as lithography or layer-by-layer assembly. Recently, nanodot array fabrication via metal deposition, e.g., sputtering and thermal evaporation, has received attention due to its simplicity and scalability. However, structures produced by deposition are often inhomogeneous and suffer from size limitations, because metals generally possess high surface energy in air. In this study, we propose a strategy for fabricating uniform metal nanodot arrays through thin oil layer-assisted solid-state dewetting. Metals are deposited by sputtering onto a glass substrate coated with a thin oil layer, followed by thermal annealing that induces dewetting and the formation of nanodot. Surfactants incorporated in the oil reduce the surface energy of metals, thereby suppressing undesired coalescence. Additionally, the size and shape uniformity of the resulting nanodots are improved and can be controlled by adjusting deposition thickness and/or oil layer thickness. This simple strategy, based on surface stabilization using oil/surfactant, effectively overcomes the limitations of deposition methods. Furthermore, nanodot arrays composed of various metals, or two or more metals, can be fabricated, providing a versatile and customizable platform for nanostructure engineering.