Surface-enhanced Raman spectroscopy on “black silicon” substrates

In this work, an array of “black silicon” silicon nanofibers was formed on a silicon substrate by cryogenic reactive ion etching and studied as a substrate for surface-enhanced Raman spectroscopy. According to scanning electron microscopy, silver particles deposited by thermal sputtering uniformly coated the black silicon nanofibers, which leads to plasmon resonance and enhancement of signal intensity. The Raman spectra of the reference samples showed no responses, while the sample coated with silver particles showed a main peak at 1436 cm$^{-1}$ corresponding to the C$_\alpha$ = C$_\beta$ bond of the PEDOT:PSS polymer, which was deposited on the substrate at a low molar concentration of 7$\cdot$10$^{-4}$ mol/L.