Nanoporous silver films produced by solid-state dewetting for SERS applications

Detection of analytes in aqueous solution with high specificity and sensitivity is of paramount importance in many fields of science, ranging from biomedicine, environmental control, and food quality assessment. Surface-enhanced Raman scattering (SERS) has proven to be a cutting-edge analytical technique for this purpose, by combining the high selectivity of Raman features with the high sensitivity deriving from the plasmonic amplification of Raman signals. Herein, we report a facile and quite effective approach to fabricate large-area Ag-based SERS substrates, exhibiting a porous, coral-like nanotexture. Due to their intrinsic large surface-area and high hot-spot density, the produced substrates appear quite promising for the detection of analytes at trace levels. The nanoporous substrates are produced by Solid-State Dewetting (SSD) of thin Ag-films. In particular, ~30 nm thickness Ag-films are first deposited on glass coverslips by magnetron sputtering. Then, marked roughening is induced by exposing the films to an Inductively Coupled Plasma (ICP) discharge, using synthetic air as feeding gas. The performances of our SERS substrates are characterized in terms of morphology and enhancement factor using CV as probe molecule.