Surface-enhanced Raman scattering (SERS) is a powerful spectroscopic technique for ultrasensitive and selective bio-chemical detection due to its capability of providing “fingerprint” information of molecular structures in low concentrations even at single molecular level. In this work, we present the silver nanoparticles/porous silicon (AgNPs/PSi) hybrid structures as SERS substrates prepared by a fast, straightforward and effective method using the PSi immersion plating in silver nitrate (AgNO3) solution. The nano-silvers can simultaneously grow on the surface and nano-pillars of porous silicon making quasi-three-dimension (quasi-3D) structural SERS substrate that has a large surface area to adsorb moleculars for SERS measurement. The proposed SERS substrate can detect Diphenylamine (DPA) with ultralow concentration of 10-9 M (~0.17 ppb), which would have higher enhancement than 2D surface SERS based on nano-silver deposited on silicon substrate and other electrochemical sensors.
