Photoreduction of SERS-Active Metallic Nanostructures on Chemically Patterned Ferroelectric Crystals

Photodeposition of metallic nanostructures onto ferroelectric surfaces is typically based on patterning local surface reactivity via electric field poling. Here, we demonstrate metal deposition onto substrates which have been chemically patterned via proton exchange (i.e., without polarization reversal). The chemical patterning provides the ability to tailor the electrostatic fields near the surface of lithium niobate crystals and these engineered fields are used to fabricate metallic nanostructures. The effect of the proton exchange process on the piezoelectric and electrostatic properties of the surface is characterized using voltage modulated atomic force microscopy techniques, which combined with modeling of the electric fields at the surface of the crystal, reveal that the deposition occurs preferentially along the boundary between ferroelectric and proton exchanged regions. The metallic nanostructures have been further functionalized with a target probe molecule, 4-aminothiophenol, from which surface enhanced Raman scattering (SERS) signal is detected, demonstrating the suitability of chemically patterned ferroelectrics as SERS-active templates. Science Foundation Ireland Higher Education Authority This publication has emanated from research conducted with the financial support of the Higher Education Authority PRTLI-5 (DGPP and NANOREMEDIES), Science Foundation Ireland (SFI10/RFP/MTR2855), and UCD Research. This work was also supported by the Swedish Scientific Research Council (VR 622-2010-526 and 621-2011-4040) and the ADOPT Linné Center. The authors are grateful to COST actions MP0702 (STSM 8171) and MP0904. S.A.L. Weber acknowledges support from the Alexander von Humboldt Foundation. Author has checked copyright kpw26/3/13