The following research paper concerns the analysis and characterisation of commercially available surface-enhanced Raman scattering (SERS) substrates. SERS has long been a potentially very powerful method with a great deal of interest around it; however, there are still many obstacles which do not allow SERS to be easily applied to real-world detection and analysis problems. As such, research around the various types of substrates is ongoing, in the hope of streamlining and improving the Raman enhancement mechanism. Scanning electron microscope images were obtained for each of the three substrates, and their features and scales were described. Enhanced Raman spectra for Rhodamine B were obtained for a range of concentrations using each of the three substrates, and, in addition, surface enhancement maps are presented. Enhancement factors were calculated for the 1358 cm⁻¹ peak of Rhodamine B. Complementing the experimental work, theoretical FEM modelling in COMSOL Multiphysics was performed, with the resulting calculations yielding an enhancement prediction adequately accurate to the real substrates.

This article presents an examination of well-controlled patterns created using a Ga⁺-based focused ion beam (FIB) on glass, while silicon substrates were used to evaluate the FIB performance by its achievable feature size versus time constraints. The pattern creation on glass was developed with the aim of studying potential surface-enhanced Raman spectroscopy (SERS) applications. Furthermore, the FIB was used to create dimer systems of periodically and randomly positioned dumbbell-shaped pits on the glass (each dimer occupies an area of 203 × 87 nm²). By following the bitmap pattern files, the FIB ensured there was 3000 dimer fabrication over a 20 × 20 μm² large area, with a pit size and position variation below 10 nm. The article highlights that FIB can be used for precise large-area nano-fabrication. The gold nanoparticle dimers were formed on the prepatterned surface via capillary force-assisted deposition. The fabricated nanostructures were tested in SERS measurements. The enhancement factor for Rhodamine B molecule reached ~10⁵, demonstrating the potential application of the method to create nanostructures in the sensor domain.

Metallic nanowires (NWs) are sensitive to heat treatment and can split into shorter fragments within minutes at temperatures far below the melting point. This process can hinder the functioning of NW-based devices that are subject to relatively mild temperatures. Commonly, heat-induced fragmentation of NWs is attributed to the interplay between heat-enhanced diffusion and Rayleigh instability. In this work, we demonstrated that contact with the substrate plays an important role in the fragmentation process and can strongly affect the outcome of the heat treatment. We deposited silver NWs onto specially patterned silicon wafers so that some NWs were partially suspended over the holes in the substrate. Then, we performed a series of heat-treatment experiments and found that adhered and suspended parts of NWs behave differently under the heat treatment. Moreover, depending on the heat-treatment process, fragmentation in either adhered or suspended parts can dominate. Experiments were supported by finite element method and molecular dynamics simulations.

In this study, we report the fabrication and characterization of silver nanoparticle-doped zinc oxide tetrapod substrates used for surface-enhanced Raman scattering to detect rhodamine B. Prior to this, silver nanoparticle-doped zinc oxide tetrapods were synthesized using the solar physical vapor deposition method. Subsequently, silver-doped zinc oxide tetrapods were applied onto silicon wafers via the droplet evaporation process. The surface-enhanced Raman scattering activity of the silver nanoparticle-doped zinc oxide tetrapod substrate was evaluated by detecting rhodamine B using Raman spectroscopy. Our results demonstrate that the silver nanoparticle-doped zinc oxide tetrapod substrate exhibits surface-enhanced Raman scattering activity and can detect rhodamine B at concentrations as low as 3 μg/mL. This study suggests that silver nanoparticle-doped zinc oxide tetrapod substrates have potential as surface-enhanced Raman scattering platforms as well as potential for the detection of biomolecules.

This study explores a novel approach to surface-enhanced Raman scattering (SERS) substrate fabrication through the heat-induced fragmentation of gold nanowires (Au NWs) and its impact on gold nanoparticle adhesion/static friction using atomic force microscopy manipulations. Controlled heating experiments and scanning electron microscopy measurements reveal significant structural transformations, with NWs transitioning into nanospheres or nanorods in a patterned fashion at elevated temperatures. These morphological changes lead to enhanced Raman signals, particularly demonstrated in the case of Rhodamine B molecules. The results underscore the critical role of NW shape modifications in augmenting the SERS effect, shedding light on a cost-effective and reliable method for producing SERS substrates.