Tuning SPR And SERS Investigation In Ordered Array Of Curved Surface

Surface-enhanced Raman Scattering（SERS）is a highly sensitive detection technique.It is very important to prepare a substrate with good reproducibility,high sensitivity and strong activity.In this paper,the self-assembly technique and magnetron sputtering system are combined to prepare SERS active substrates with periodic arrangement and strong enhancement factor.The microstructures and SERS properties were studied.The main research contents are as following:1,The SiO₂/Ag/SiO₂ three-layer films were deposited on the PS colloidal sphere arrays.The effect of annealing temperature on the structure and properties was studied.With temperature increase,the curvature and stress of the SiO₂ increase.However,Periodic structures remain unchanged,which indicates that SiO₂ has good mechanical properties for maintaining the shape of the nanocaps.The stress acts on the Ag layer which leads to Ag grains growth,and produces the nanotwins in the nanocaps.The increase of Ag grains size leads to that the LSPR bands gradually red shifts and broad,which originats from the Ag grains size increase.With the temperature increase,the size and the gap of the SiO₂/Ag/SiO₂ nanocap structures are changed.The“hot spots”and SERS intensity between adjacent nanocaps are decreased;The surface of nanocaps become smooth,which is resulted in“hot spots”decrease in nanocaps.The SiO₂/Ag/SiO₂ nanocap arrays with Ag twins have good thermal stability and SERS properties.2,TiS₂ is narrow band gap semi-metal with surface plasmon resonance（SPR）characteristics.SPR peak of TiS₂ can reach the near-infrared region,but TiS₂ don’t have SERS activity.The SPR of noble metal Ag has excellent SERS performance in the visible region.The SPR of Ag can be shifted to the near-infrared region by deposited Ag on the PS bead arrays.The SPR of Ag and TiS₂ in Ag/TiS₂ nanostructure have synergistic effects,in which SPR can be shifted to the near-infrared region with the increase of TiS₂ thickness.The carrier concentration decreases when the SPR is red shifted.The SERS activity of Ag/TiS₂ nanostructures was significantly enhanced with the addition of TiS₂.This is because the charge transfer between TiS₂ and the probe molecule.It is an additional contribution to the enhancement of the SERS signal.The SERS signal of Ag/TiS₂ nanostructures decreases with the increase of TiS₂thickness,which is attributed to the shielding effect of TiS₂ layer for Ag SPR.3,Co-sputtering TiS₂ and Ag on the PS ball arrays to investigate the effect of TiS₂ content for the SERS signal of TiS₂-Ag nanostructure.With the TiS₂ content ratio increases the carrier concentration decreases,which results in the SPR red shift.The amorphous TiS₂ inhibits the growth of Ag nanoparticles,which leads to increase first and then decrease of TiS₂-Ag composite nanoparticles size and the surface roughness.The SERS performance test indicated that the TiS₂-Ag substrates have good SERS activity with the addition of TiS₂.When the sputtering power of TiS₂ is 120 W,the surface roughness is the largest,and the SERS enhanced factor of TiS₂-Ag substrates is 1.60×10⁹.