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Periodic Silver and Gold Nanodot Array Fabrication on Nanosphere Lithography-Based Patterns Using Electroless Deposition

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posted on 01.07.2020 by Sasanka B. Ulapane, Nilan J. B. Kamathewatta, Ashley K. Borkowski, Samuel J. Steuart, Cindy L. Berrie
Precision-controlled fabrication of metallic nanostructures is of great interest in applications such as sensing, optoelectronics, and high-capacity storage devices. However, the expense and throughput of the current methods limit the applicability of metal nanodot arrays for many of these applications. This issue is addressed by a method for generating periodic silver (Ag) and gold (Au) nanodot arrays in a straightforward, inexpensive, tunable way. Specifically, regularly placed hexagonal arrays of Ag and Au nanodots were fabricated on Si(111) surfaces via a nanosphere lithography-based approach followed by electroless deposition (ELD). Silicon surfaces with hexagonally packed nanospheres were reacted with octadecyltrichlorosilane (OTS) to form a self-assembled monolayer resist over the substrate, which leads to a hexagonal array of nanopores upon removal of the spheres. Different electroless plating solutions for Ag and Au were introduced onto the nanopore surfaces to selectively deposit metal in the nanopores, resulting in metal nanodots grown only in the nanopores, where the nanospheres were originally in contact with the substrate. Ag and Au nanodot heights can be effectively tuned from 20 to 100 nm by varying the plating time and the composition of the plating solution. Atomic force microscopy (AFM) was used to characterize the height and diameter of the nanopore and nanodot arrays along with energy-dispersive X-ray spectroscopy (EDS) to characterize the elemental composition distribution on the surface. This method provides control over the distance between nanodots and their size at the nanoscale with high reproducibility.

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