Development of High-Performance SERS Substrates Using Arc Plasma-Coated Nanostructures on Porous Silicon

This study introduces an innovative approach to developing active substrates for molecular detection by enhancing surface-enhanced Raman scattering (SERS). The substrates were fabricated using porous silicon coated with nanostructures, which were produced via the electrical exploding wire (arc plasma) technique. The research focused on examining the influence of plasmonic nanostructure morphologies on absorption spectra and SERS performance, using Rhodamine 6G (Rh6G) dye as the test analyte. The structural properties of the nanostructures were characterized through X-ray diffraction (XRD), while their morphologies were analyzed using field-emission scanning electron microscopy (FE-SEM). Atomic force microscopy (AFM) was employed to investigate the surface topographies of the substrates, optimizing them for SERS applications. The absorption of Rh6G dye at a concentration of 1×10^-5 M was measured with a double-beam UV-Vis spectrophotometer, and the impact of different nanostructure concentrations was evaluated. Raman spectra analysis was conducted using a Sunshine Raman spectrometer with a 50x objective lens, comparing the performance of substrates made from silver nanowires on porous silicon (PSi-AgNWs) and silver nanowires decorated with silver nanoparticles on porous silicon (PSi-AgNWs@AgNPs).The findings demonstrated that hot spots and surface roughness in the nanostructures significantly enhanced SERS signals and absorption spectra. With a laser source at λexc.=532 nm, the SERS enhancement factor (EF) for Rh6G at a concentration of 0.1 M reached (26.716 × 104) and (31.219 × 104) for the characteristic peak at 1652 cm-1, using PSi-AgNWs and PSi-AgNWs@AgNPs substrates, respectively