Fabrication and Geometric Analysis of Multilayered Surface‐Enhanced Raman Scattering Substrates Using the Focused Ion Beam Method

Surface‐enhanced Raman scattering (SERS) requires surfaces with a high degree of control over their morphology. Homogeneity and precision in both the geometry and the constituent materials of the surface are needed. For this end, two methods are employed. Sputtering of nanometer‐scale gold and silica layers is conducted, followed by patterning using the focused ion beam (FIB) method. The FIB method allows for the fabrication of precise structures with well‐defined geometric parameters. With the substrates, the study inquires into the relationship between these parameters and the Raman signal enhancement yielded by the active surface. The substrates feature nanopillar structures with differing geometric parameters. Relationships have been obtained between the parameters and the Raman signal enhancement. These are complemented by finite element method (FEM) computations closely simulating the actual structures. The resulting substrates are capable of detecting analyte concentrations of rhodamine B down to 1 nM and have a limit of detection of ~10 −11 M.