DC sputtering-driven self-organization of sub-10 nm silver nanoparticles into optically active monolayers with 460 nm resonance

Abstract In this work, we present a simple, scalable, and reproducible physical strategy to fabricate functional monolayers of sub-10 nm silver nanoparticles (AgNPs) via DC sputtering. Using a 6N-purity Ag target and optimal conditions of 60 W, 1.8 × 10 −3 Torr, and 2 s of deposition, we obtained quasi-spherical AgNPs homogeneously distributed over glass and nitrocellulose substrates, with an average Feret diameter of 8.7 ± 4.8 nm and an interparticle spacing of 25% relative to their size. The resulting structures exhibited high morphological reproducibility across multiple deposition cycles, as confirmed by SEM, TEM, HRTEM, and STEM, and showed a sharp and intense localized surface plasmon resonance (LSPR) at 460 nm. I–V measurements revealed an abrupt electrical percolation threshold at 5 s, with current increases exceeding eight orders of magnitude compared to non-conductive samples (≤4 s). Films deposited between 5 and 10 s displayed increasingly steep I–V slopes, indicating reduced electrical resistance due to enhanced particle connectivity, although all percolated samples exhibited electrical breakdown at their respective power dissipation limits (0.17–0.44 W). HRTEM and FFT analyses confirmed the face-centered cubic (FCC) crystal structure of the AgNPs and the presence of a thin Ag 2 O surface layer. Finally, numerical simulations supported our experimental results, showing that prolonged deposition times promote agglomeration and that larger source-to-substrate distances induce greater angular dispersion, reducing spatial uniformity.