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.