Silver substrates for surface enhanced Raman scattering: Correlation between nanostructure and Raman scattering enhancement

• Published in: Applied physics letters 2014-06, Vol.104 (24), p.243107
• Main Authors: Santoro, G., Yu, S., Schwartzkopf, M., Zhang, P., Koyiloth Vayalil, Sarathlal, Risch, J. F. H., Rübhausen, M. A., Hernández, M., Domingo, C., Roth, S. V.
• Format: Article
• Language: English
• Subjects: Applied physics; Deposition; Fysik; Nanostructure; Percolation; Physics; Raman spectra; Silicon substrates; Silver; Small angle X ray scattering; Thin films; Thiophenol
• ISSN: 0003-6951; 1077-3118; 1077-3118
• DOI: 10.1063/1.4884423

The fabrication of substrates for Surface Enhanced Raman Scattering (SERS) applications matching the needs for high sensitive and reproducible sensors remains a major scientific and technological issue. We correlate the morphological parameters of silver (Ag) nanostructured thin films prepared by sputter deposition on flat silicon (Si) substrates with their SERS activity. A maximum enhancement of the SERS signal has been found at the Ag percolation threshold, leading to the detection of thiophenol, a non-resonant Raman probe, at concentrations as low as 10−10M, which corresponds to enhancement factors higher than 7 orders of magnitude. To gain full control over the developed nanostructure, we employed the combination of in-situ time-resolved microfocus Grazing Incidence Small Angle X-ray Scattering with sputter deposition. This enables to achieve a deepened understanding of the different growth regimes of Ag. Thereby an improved tailoring of the thin film nanostructure for SERS applications can be realized.