Sputter deposition of Ag on SiOx and PDMS thin films for SERS applications

Abstract

Silver (Ag) nanoclusters present excellent plasmonic properties that can be exploited for Surface Enhanced Raman Scattering (SERS) based sensors. However, to optimize the sensitivity of SERS substrates, it is crucial to achieve a profound understanding of the Ag nanocluster growth kinetics and to correlate the thin film morphology with its functionality.1 In this sense, Grazing Incidence Small Angle X-ray Scattering (GISAXS) constitutes a very powerful technique to extract information on the nanostructure development with high statistical relevance and temporal resolution in the order of milliseconds.2 This work presents in-situ time-resolved GISAXS1,3-5 results concerning the evolution of the nanostructures developed during the RF-sputtering of Ag on semiconductor (SiOx) and polydimethylsiloxane (PDMS) thin films, a highly flexible and stretchable silicone widely used for microfluidics. The SERS activity of the prepared thin films and the correlation of morphology and sensitivity are also presented using the model of Schwartzkopf et al.4