Size-dependent SERS detection of R6G by silver nanoparticles immersion-plated on silicon nanoporous pillar array

► A series of Ag/Si nanoporous pillar arrays (Ag/Si-NPAs) were prepared controllably. ► The SERS detection of rhodamine 6G with a concentration of 10−15 M was performed. ► The SERS effect depended highly upon the size of the deposited silver particles. ► The optimal silver particle size for obtaining strong SERS effect was ∼35-55 nm.