Sensitive and Reliable SERS Substrates Based on Hierarchical Nanoparticle Arrays Fabricated by Confined Spheroidization

Abstract

Abstract Substrates with complex and hierarchical nanostructure are widely investigated in surface‐enhanced Raman scattering (SERS), but it remains challenging to improve the structural uniformity and stability. Herein, a novel method is proposed: confined spheroidization. Unique configurations of hierarchical metallic nanoparticle arrays (HMNA) are successfully fabricated by confined spheroidizing on anodic aluminum oxide templates. By utilizing the confined effect of the holes, a series of large particles inside the hole and small particles arranged on the hole wall are obtained after thermal annealing. The size and distribution of nanoparticles strongly depend on the hole size, the thickness of the hole wall, and the deposition thickness of metal layer. COMSOL simulations demonstrate good SERS activity of the HMNA, with a low detection limit of ≈10 −8 m for crystal violet (CV) and the enhancement factor of ≈ 4.97 × 10 7 at the 1160 cm −1 mode of CV. The relative standard deviation of 6.23% from 59 random spots and a 9.24% signal variation among ten substrates are achieved, showing good SERS signal reproducibility of the HMNA. This simple and low‐cost technique makes it possible to prepare 3D hierarchical ordered micro–nanostructures by one‐step, showing prospect applications in SERS‐based detection and plasmonic materials.