Femtosecond and nanosecond laser fabricated substrate for surface-enhanced Raman scattering

Abstract

We report a simple and repeatable method for fabricating a large-area substrate for surface-enhanced Raman scattering. The substrate was processed by three steps: (i) femtosecond (fs) laser micromachining and roughening, (ii) thin-film coating, and (iii) nanosecond laser heating and melting. Numerous gold nanoparticles of various sizes were created on the surface of the silicon substrate. The 3D micro-/nanostructures generated by the fs laser provide greater surface areas with more nanoparticles leading to 2 orders of magnitude higher of the enhancement factor than in the case of a flat substrate. Using an He-Ne laser with a 632.8 nm excitation wavelength, the surface-enhanced Raman scattering enhancement factor for Rhodamine 6G was measured up to 2×10(7).

Surface-Enhanced Raman Spectroscopy of Graphene Integrated in Plasmonic Silicon Platforms with Three-Dimensional Nanotopography

“…Graphene on nanostructured silicon leads to additional modifications of the nanoparticle morphology 34 . Thus, the optical properties of the plasmonic substrates may be tuned according to the application 29,30,34 . For all wavelengths, the D peak appears more intense for the nanostructured silicon substrates (coated and uncoated).…”

“…Coating these micro/nanopatterned 5 surfaces with thin metallic layers results in the spontaneous formation of metallic nanoparticles, rendering them plasmon-active. Nanosecond and femtosecond laser-patterned silicon wafers, coated with metallic thin films and nanoparticles, have been used as efficient SERS substrates with liquid analytes recently [29][30][31][32][33][34][35][36] . Nanostructured silicon with gold nanoparticles was employed as a SERS substrate for Rhodamine 6G spectroscopy and provided enhancement factors of 10 4 31 and 10 7 33,34 .…”

“…Nanosecond and femtosecond laser-patterned silicon wafers, coated with metallic thin films and nanoparticles, have been used as efficient SERS substrates with liquid analytes recently [29][30][31][32][33][34][35][36] . Nanostructured silicon with gold nanoparticles was employed as a SERS substrate for Rhodamine 6G spectroscopy and provided enhancement factors of 10 4 31 and 10 7 33,34 . Arrays of silicon nanopillars with silver nanoparticles demonstrated high sensitivity and reusability as a SERS substrate for Rhodamine 6G and Methylene blue 35 , while resulting in a Raman enhancement factor of 10 9 for melamine molecules 36 and 10 7 for benzenethiol 30 .…”

Plasmon enhanced optical tweezers with gold-coated black silicon

“…The size and density of the metal nanoparticles depends on the amount (nominal thickness) of the metal coating, the deposition rate, and the substrate temperature 29 . Post-deposition laser heating and melting of the metallic layer can lead to additional modifications of the nanoparticle morphology 41 . Tuning the fabrication parameters allows for controlling the morphology and optical properties of the plasmonic substrates, including the resonance wavelength, and maintaining the repeatability in the measurement of the trapping efficiencies observed here.…”

Microstructured polymer‐based substrates with broadband absorption for surface‐enhanced Raman scattering

“…For the latter, femtosecond (fs) laser machining has recently become a popular fabrication technique. [13][14][15][16] But the drawbacks of the laser machining are high costs and time consumption. In this respect, soft lithography, which provides a simple way for replication of the substrates, can serve as a convenient method for mass fabrication.…”