Microstructure Evolution of Ag/Ta Nanostructured Films for Surface- Enhanced Raman Scattering Substrates

Surface-enhanced Raman scattering (SERS), a nondestructive, ultrasensitive detection method, has a wide range of potential applications. However, its application is limited due to the weak Raman scattering signals. Therefore, it is urgent to explore a simple physical method to prepare SERS substrates with high detection limits and excellent reproducibility. In this work, Ta-Ag alloy films were prepared by magnetron sputtering at room temperature, and a large number of Ag nanoparticles were self-formed on the alloy films' surface by adjusting the deposition time, Ag content, and annealing temperature. Further research reveals that this is because the amorphous Ta in the alloy films prevents the growth of Ag grains inside Ta-Ag alloy films, resulting in the diffusion of Ag atoms to the alloy film's surface to form Ag nanoparticles. The results demonstrate that Ag nanoparticles/Ta 55.5 at % Ag alloy films used as SERS substrates have excellent reproducibility and high sensitivity to detect 5 x 10-16 mol L-1 rhodamine 6G (R6G) solution and 5 x 10-12 mol L-1 crystal violet (CV) solution. This method provides a simple approach to developing high-performance SERS substrates.