One-step construction of regular cascade nanostructure and its near-field properties

Highlights: • Large area of uniform Ag cascade nanoparticle arrays (Ag-CNPAs) were obtained. • Ag-CNPAs were obtained by special angle vacuum thermal evaporation technique. • FDTD simulation shows that the Ag-CNPAs structure has more hotspots. • The prepared Ag-CNPAs are very promising devices. Uniform and simple construction of metal plasmon nanostructures has become popular for many applications. Thermal evaporative deposition technology has attracted widespread attention in recent years due to its excellent controllability and technical universality. In the current study, large area of uniform Ag cascade nanoparticle arrays (Ag-CNPAs) with multi-scale coupling effect were obtained by one-step method using the confined evaporation deposition technique. Finite-difference time-domain (FDTD) simulation findings demonstrated that Ag-CNPAs have apparent cascade enhancement feature of gradual energy coupling and convergence. Using prepared Ag-CNPAs as surface-enhanced Raman spectroscopy (SERS) active substrates, relative standard deviation (RSD) value of Raman intensity at 1160 cm⁻¹ mode of crystal violet (CV) molecules (with concentration of 10^-4 M) was 2.6 %, which indicated homogeneity and excellent near-field enhancement performance of Ag-CNPAs nanostructures. Furthermore, the current study established that SERS substrates were very promising devices. In addition, the current study developed a localized deposition technology that is simple to operate and cheap, which is valuable in large-scale uniform preparation of complex micro-nano structures.