The battle for the future of SERS – TiN vs Au thin films with the same morphology

This work compares for the first time the SERS activity of TiN and Au nano/micro-structures having the same morphology. Si pyramids formed by alkaline etching were coated with Au and TiN layers of three different thicknesses (20, 57 and 80 nm). The morphology of both platforms was investigated using SEM microscopy. The optical properties were examined by spectroscopic ellipsometry and diffuse reflectance spectroscopy. The results prove that both the Si/TiN and Si/Au microstructures exhibit plasmonic properties in the visible range, and can be effectively applied as SERS platforms. Two dyes were chosen as the Raman reporter molecules. Data analysis showed the highest EF for the thickest layer of the deposited Au and TiN layers. It was found that, for the 80 nm layer on both Au and TiN, even as low as 10-9M concentrations of tartrazine could be detected. In both cases, the SERS platform could be cleaned by rinsing in distilled water, and then re-used. It was found that for the Si-Au pyramids the reversibility was equal to 13, while the Si-TiN could be washed even after 20 cycles.