Surface‐Enhanced Raman Scattering (SERS) Substrate Based on Large‐Area Well‐Defined Gold Nanoparticle Arrays with High SERS Uniformity and Stability

Abstract A fabrication process that combines an ultrathin alumina membrane (UTAM) surface nanopatterning technique and a physical vapor deposition method has been designed for realizing well‐defined Au nanoparticle arrays for sensitive, uniform, and stable surface‐enhanced Raman scattering (SERS)‐active substrates. High Raman signals are obtained by adjusting the structural parameters of the metallic nanoparticles when rhodamine 6G (R6G) and 4‐mercaptopyridine (4‐MP) are used as the probe molecules. The corresponding estimated enhancement factors (EFs) are 6.5×10 6 (R6G) and 6.8×10 5 (4‐MP), respectively. The simulated distributions of the electric field of SERS substrates coincide with the experimental results. Raman measurements at randomly selected spots on a substrate show a standard EF deviation of about 5 %, which indicates a desirable SERS uniformity. An advantageous feature of our SERS substrate is its long‐term stability of enhanced Raman signals. Raman measurements on a substrate after one year show almost the same magnitude of Raman signal (10 6 for R6G and 10 5 for 4‐MP) as that of the original measurement. Such substrates with good SERS sensitivity, uniformity, and stability should have high potential for SERS‐related applications.