Figure 4. Raman spectra of a 40-nm SiO_x film annealed at 1100 °C measured using a 10× objective and 488-nm laser with an exposure of 60 s for the uncoated (no Ag, red curve) and Ag-coated (Ag, 12 nm, blue curve) SiO_x film.

The Raman band at ~517 cm⁻¹ originates from Si-nc with diameters of 3–4 nm. The broad bands measured for the uncoated film are from the silica substrate.