n-Type porous silicon as an efficient surface enhancement Raman scattering substrate

Highly active and sensitive surface-enhanced Raman scattering (SERS) substrates were prepared by n -type (1 to 10  Ω⋅cm in resistivity) porous silicon (PS) substrates of Ag nanoparticles. SERS studies were carried on these substrates with R6G as a test molecule with a λ ex =785  nm laser. We optimized the fabrication procedure, which is easy and rapid, for nanostructured silver particles on the surface of PS. The maximum of SERS enhancement for R6G is observed for PS with an anodization current density of 6  mA/cm 2 and an etching time of 8 min. The detection limit for R6G absorbed on Ag-coated PS (Ag-PS) is 10 nM and SERS spectra show that the Ag-PS substrate has high SERS activity. The larger pore diameter of this new Ag-PS substrate is expected and the size of the pore diameter is about 1.2 μm, which permits better biomolecule infiltration. This new Ag-PS substrate can be applied in SERS in biochemical and biomedical fields.