Hemispherical Silver Nanoshell Array on Silicon Nanospheres for Surface-Enhanced Raman Spectroscopy

This work introduces a novel method for fabricating surface-enhanced Raman scattering (SERS) substrates using localized laser annealing of silicon nanopillars and deposition of silver thin film. The laser annealing induces morphology transformation from cylindrical nanopillar array to nanosphere array with the aid of out-of-plane temperature gradient. Then, thermal evaporation of silver forms hemispherical nanoshell array on top of nanosphere array with the gap between nanoshells approximately 20 nm. With this nanogap, Raman spectra of L-Cysteine are acquired with a significant enhancement.