Ordered Arrays of Ultrafine Au Nanoprisms by Means of Nanosphere Lithography and Ion Hammering Effect

The search for new nanomaterials with precisely customized optical and geometric characteristics is highly suitable for potential applications in nanophotonics and optoelectronics. In this work, ordered arrays of ultrafine Au nanoprisms on silicon substrates were prepared by combining nanosphere lithography with the ion hammering effect. Indeed, the silica particle lithographic masks were previously irradiated with 4 MeV Si⁺ ions to modify and tune the mask interstice size. An extensive analysis of the samples by SEM and AFM determined the geometrical properties and the narrow average size of the ultrafine Au nanoprisms, exhibiting an area base of 750 nm², a lateral size as small as 26.2 nm, and a height of 6.3 nm. Moreover, the Surface-Enhanced Raman Scattering (SERS) efficiency of the fabricated ultrafine Au nanoprisms was probed using Rhodamine 6G dye as probe molecules, presenting excellent stability and reaching the sensitivity level of 10⁻⁵ M.