Rapid templated fabrication of large-scale, high-density metallic nanocone arrays and SERS applications

A simple and universal templating approach is developed for fabricating large-scale ordered metallic nanocone arrays with high density (5 × 10⁸ tips cm^-2). A silicon nanocone array is prepared as the original template to form conical pits in a soft polymer template by thermal nanoimprinting. After metal deposition fills the pits, the resulting large-scale metallic nanocone array with sharp nanotips can be adhered to and peeled onto another polymer substrate by a simple, novel process. Avoiding the challenges of peeling from a hard template, a crucial baking process enables peeling, taking advantage of the difference in glass transition temperature (GTT) between the respective soft polymer materials of the deposition template and the transfer substrate. The method as a whole is designed for perfectible formation of a variety of metallic nanocone arrays. It provides a universally reliable shortcut to fabricate large-scale metallic nanocone arrays without lithography or etching steps, and it can be extended to the fabrication of other three-dimensional metallic-array nanostructures. Further, the as-formed Ag nanocone arrays show a large, stable surface enhancement for Raman scattering due to the nanofocused effect of the electromagnetic field induced by the conical nanostructures.