Fabrication of Ag based Surface Enhanced Raman Scattering substrates with periodic mask arrays by electron beam deposition

Abstract

Background: Surface-enhanced Raman scattering (SERS) has attracted much attention as a powerful detection and analysis tool with high sensitivity and fast detection speed. The intensity of the SERS signal mainly depended on the highly enhanced electromagnetic field of nanostructure near the substrate. However, the fabrication of high-quality SERS nanostructured substrates is usually complicated, makes many methods unsuitable for large-scale production of SERS substrates. A new strategic preparation method is needed, which is simple and inexpensive in the preparation process, can achieve large-scale mass production, and also ensures the good performance of the SERS substrate.

Results: For the first time, we propose constructing a silver (Ag) surface-enhanced Raman scattering (SERS) substrate with different angular quadrilateral periodic arrays by combining a mask plate and vapor deposition. The mask plate can precisely control the period and angle of the nano-arrays, and thus regulate the intensity of the local "hot spots". The analytical results show that the tetragonal periodic Ag SERS substrate with a 15° angle of the mask plate exhibits a significant enhancement effect in the detection of Rhodamine 6G (R6G), Rhodamine B (RhB), and Methyl Orange (MO) probe molecules, and the limit of detection (LOD) of this substrate is low as 10^-11 mol/L for all the three solutions. The enhancement factors (EFs) are 6.5 × 10⁶, 4.2 × 10⁵, and 2.6 × 10⁵, respectively. The accuracy of the experimental results was further verified through a finite-difference time-domain (FDTD) simulation.

Significance and novelty: In this paper, we propose that the SERS substrate was fabricated using the new strategy with a lower detection limit for multiple dye molecules simultaneously. The results show that the SERS substrate prepared in this study has great potential for applications in high-performance SERS sensors. Additionally, this new preparation method may also be applicable to other metal materials, offering broad research prospects.

Keywords: Ag; FDTD; Masking method; Periodic arrays; SERS.