Internal Structure Tailoring in 3D Nanoplasmonic Metasurface for Surface‐Enhanced Raman Spectroscopy

Abstract

AbstractTunable nanoplasmonic metasurfaces have resulted in many versatile platforms for sensing applications including surface‐enhanced Raman scattering (SERS)‐based detection. However, to date, their fabrication still faces challenges in uniformity, repeatability, and controllability. Here, a novel large‐area and hierarchical nanoplasmonic array with controlled internal structure and tunable plasmonic properties is reported, relying on controllably tailoring the single nanosphere on a uniform double‐layered array into a well‐defined nanoflower structure. The fabrication involves colloidal self‐assembly, lithography, and plasmonic metal coating. First, a uniformly distributed double‐layered colloidal array is fabricated via an ethanol‐assisted self‐assembly technique. Next, with the help of inductively coupled plasma dry etching, the lower layer is transformed to the nanoflower array with well‐defined petal shape. Subsequently, a gold film with controlled thickness is deposited onto the nanoflower structured array, resulting in a tunable optical and SERS‐active enhancement effect. Furthermore, 3D finite‐difference time‐domain simulation shows multiple enhancement sites inside the nanoflower array. Such a brand‐new 3D structured array has the potential for varied applications, ranging from SERS sensors to light regulation.