Surface-enhanced Raman Scattering (SERS) serves high-sensitivity technique for low-concentration and label-free detection of the fingerprint spectrum. SERS-based analyte sensing is attributed to the local electromagnetic (EM) field concentration, termed hotspots, that occur due to the gaps and edges between noble metal nanostructures [1]. Structures with nano-size gaps such as bow-tie geometries attract considerable attention from researchers as they can enhance EM fields significantly via plasmon coupling effects [2,3].
Since the SERS performance of noble metals is highly dependent on their geometry, we simulated the EM near fields in gold bow-tie triangle arrays employing the finite-difference time-domain (FDTD) method which is an effective computational method for examining nanostructures. The optical behavior of the edge sharpness and tip-to-tip gap parameters of the gold bow-tie triangle arrays were investigated. For the periodicity properties of the simulation region, boundary conditions were chosen as anti-symmetric for the X direction, symmetric for the Y direction, and perfectly matched layer (PML) for the Z direction. A 5 nm mesh was used for FDTD simulations the adjustments were made for the 785 nm resonant wavelengths. Optimization studies from sharp tips to 50 nm radius tips and nanogaps ranging from 0 to 200 nm showed that bow-tie structure with small nanogaps 5 nm, 10 nm, and 15 nm could enhance the incoming EM field intensity and SERS enhancement factor of approximately by up to 2.3 x 10\(^{3}\) and 3.9×10\(^{5}\), respectively. It was found that the gold bow-tie triangle array exhibits excellent SERS performance and significantly increases the EM field and SERS enhancement factor. This work was supported by the Research Council of Lithuania (RCL) (Project no.: S-PD-24-115).