Morphological Design of Gold Nanopillar Arrays and Their Optical Properties

The fabrication of large areas of gold nanopillar arrays by combining nanosphere lithography and electrodeposition of metals is demonstrated here for the first time. Both the morphology and the surface density of the nanopillars can be finely tuned by controlling the size of the colloidal beads used in the template, the sintering time of the template and the electrodeposition time of metals. The colloidal templates are removed after electrodeposition, and the nanopillar arrays can be transferred onto a transparent polydimethylsiloxane substrate and optically characterized. Our focus here is on the ease and versatility of this technique to prepare large two-dimensional arrays of plasmonic gold nanopillars and their resulting optical properties. By making use of finite difference time domain numerical simulations, the excitation of localized surface plasmon resonances of the individual nanopillar with a strong dipolar character is observed, which is characteristic of such uncoupled metallic nanostructures. Experimental optical measurements are also in good agreement with the simulations, confirming the successful engineering of the nanostructures.