Superplastic Nanomolding of Highly Ordered Metallic Sub-Micrometer Pillars Arrays for Surface Enhanced Raman Scattering

Ordered metallic nanostructures, due to their superior electronic and photonic properties, have played a vital role in wide range of applications, such as metamaterials, plasmonic sensing, electrocatalysis, and energy devices. However, traditional fabrication strategies based on bottom-up self-assembly and top-down lithography are either poor in uniformity or time-consuming with low scalability. Here, a robust and cost-effective approach for the fabrication of highly ordered metallic pillars arrays in centimeter scale is presented. This is realized by superplastic nanomolding of metals with highly ordered anodic aluminum oxide templates which are fabricated by the prepatterning of aluminum sheets with bulk metallic glass (BMG) mold, followed by anodizing. The nanopatterning process is rationalized with finite element simulation to avoid the damage of BMG mold. Finally, it is shown that the molded metallic sub-micrometer pillars arrays can be used for the surface-enhanced Raman scattering (SERS) with enhancement factor of ≈10⁶. It is found that the SERS performance is influenced by the specific surface area of the pillars in addition to the near-field intensity. This simple and cost-effective method not only opens new opportunities for rapid prototyping of large-scale ordered metallic nanostructures for various applications but also provides guidance for the quantitative analysis on sub-micrometer scale.