Spatial Analysis of Nanostructured Au-Ag Alloys as SERS Substrates towards Increased Performance and Shelf LifeThursday (27.09.2018) 10:00 - 10:15 S1/03 - 226 Part of:
In recent advancements of surface-enhanced Raman spectroscopy, fabrications of most SERS substrates have been focused on nanostructures towards highly enhanced SERS performance. This work however proposed an alternative method to fabricated nanostructured alloys of novel metals towards both SERS performance and increased shelf life. For the proposed SERS substrates, nanorods of Au-Ag alloys were prepared by a co-sputtering deposition with an oblique-angle deposition technique. With a fixed sputtering power for the Ag target, a variation of a sputtering power for the Au target, which greatly affected length and diameter of the alloy nanorods, was thoroughly investigated. The SERS substrates with the same alloy thickness were obtained by adjusting the deposition time for each sputtering parameter. From the fabricated SERS substrates, physical morphologies were examined by field-emission scanning electron microscopy and high-resolution transmission electron microscopy. The element compositions of the fabricated nanorod alloys were performed by X-Ray photoelectron spectroscopy (XPS). The SERS performance was investigated with a portable Raman spectroscopy, where trace concentrations of dye indicator solution were used as probe molecules. The results showed that, at 300 nm thickness of the Au-Ag alloy nanorods, slanted nanostructures were observed with partially isolated columnar structures, because the applied OAD technique helped enhance shadowing and limited adatom diffusion effects. In addition, the increased Au sputtering power also resulted in the increased dimensions in the nanorod length and diameter. The XPS investigations demonstrated that, with the increased sputtering power of the Au target, the Au content of the fabricated SERS alloys was also increased. Finally, the Raman performance and shelf life were investigated and discussed, in comparison with the Au-Ag content percentage.