Highly ordered Si-based ZnO/Ag bilayer structure for recyclable SERS substrates with ultra-sensitivity.

Compositing semiconductors with noble metal is considered as an effective strategy for improving SERS enhancement attributed to synergistic contribution of LSPR and CT mechanisms. In this work, highly ordered ZnO/Ag bilayer structures on p-type silicon wafers are prepared by photolithography and electrochemical self-assembly. The synergistic effect of EM and CT for SERS enhancement is identified by the Raman, PL spectra and 3D FDTD simulation. Flower-like Ag deposited on coarse ZnO films exhibits high SERS sensitivity. The ultra-low concentration of R6G molecules as low as 10−15 M can be detected, and the EF is estimated to be 8.08 × 1013. Due to the excellent photocatalytic property of ZnO, the bilayer structures possess steady and effective UV-cleaning performance. After being UV irradiated for 10 min, this SERS substrate can be re-used for many times. And the detecting RSD is about 4.11 %. The multi-functional ZnO/Ag bilayer structures with a wide direct bandgap has the prominent capacity to provide an efficient charge transfer path to possess trace detection ability for many probe molecules. [ABSTRACT FROM AUTHOR]