Ag-Coated Si nanowire arrays: A new route for the precise detection of fungicides by surface enhanced Raman scattering

In this study, we present an efficient method based on vertically oriented silicon nanowire arrays coated with silver nanoparticles to achieve significantly surface enhanced Raman scattering (SERS) signals. The method is applicable for the accurate detection of fungicides and related compounds. The substrates were obtained by a two-step process consisting of the growth of Si nanowire arrays on a silicon wafer by metal-assisted chemical etching and subsequent coating with Ag nanoparticles by the sputtering method. The effect of sputtering time on the growth of nanowires, their morphology and enhancement factor of the signals obtained from the SERS sensor were studied in detail. The final enhancement factor of Raman shift is 1.1 × 107, allowing the limit of trace detection for carbendazim to be as low as 0.1 ppm, with a relative standard deviation of less than 2.07%. This result opens up the potential for direct application of prepared substrates in ultra-fast chemical analysis.