A highly-ordered three-dimensional petal-like arrayed structure for highly surface-enhanced Raman scattering

This paper reports for the first time a novel highly-ordered three-dimensional (3D) petal-like arrayed structure (PLAS) which can serve as an ideal substrate for surface-enhanced Raman scattering (SERS). The structure is achieved by anisotropically etching a hexagonal close-packed silica nanoparticle (SNP) bilayer coated on a silicon substrate through evaporation-induced self-assembly, and then depositing a silver film. SERS experiments with excitation wavelength at 632.8 nm show that the SERS enhancement factor of the PLAS is 8 times higher than that of monolayer SNP arrays, and longer etching time, which changes the shape and interspace, thus hot spots of the structure, can achieve higher SERS enhancement factor.