Fabrication of 3D surface-enhanced Raman scattering (SERS) substrate via solid-state dewetting of sputtered gold on fumed silica surface

Abstract

Raman spectroscopy is a potent and widespread optical analytical technique thanks to its non-invasive and high-specification for the detection of targeted molecules. However, for the case of trace detection, it is common that a weak Raman signal is easily swamped by noise and thus unable to be resolved. Here, we demonstrated a facile fabrication of a three-dimensional surface enhanced Raman spectroscopy (SERS) substrate, based on low-vacuum sputtering of gold nanofilm on hierarchically rough fumed silica monolayers deposited by layer-by-layer self-assembly technique. Due to the much lower surface energy of the silica-air heterostructure compared to metallic materials, deposited gold layers dewetted the surface spontaneously, forming nano-sized spherical gold particles without the requirement of an extra annealing process. Plasmonic effects were studied through optical absorption measurements, while the surface morphology and topography were examined using SEM and AFM for various sputtering durations. Furthermore, the enhancement of Raman spectrum was investigated for 10−4 M of methylene blue (MB), using 532 nm and 0.57 mW excitation laser. An initial Raman enhancement factor of 17 was observed at 1645 cm−1 peak, even with yet to be optimized fabrication procedures.

Effect of the Substrate Crystallinity on Morphological and Magnetic Properties of Fe70Pd30 Nanoparticles Obtained by the Solid-State Dewetting

“…The solid-state dewetting process applies to a wide class of materials and alloys [19,22,[24][25][26][27]. Interestingly, this process occurring in noble metals (Au and Ag) supports the development of the plasmonic sensors based on surface-enhanced Raman scattering (SERS) effect by the fabrication of suitable nanostructured substrates with high performance and low cost [21,28,29]. On the other hand, the solid-state dewetting applied to single-and multi-layer magnetic thin film strengthens the understanding of the correlation between the technologically relevant magnetic properties, such as anisotropy, susceptibility, coercivity, remanence and the morphological features of the obtained NPs [24,25,30].…”

“…In this context, solid-state dewetting is a physical, "top-down" and low-cost nanofabrication technique [17,18] able to induce a morphological transformation of a thin film into an ordered nanoparticles array, usable as a key component in catalysts, photonic and magnetic applications as well as in several sensors [19][20][21][22]. The thermally activated morphological transformation is driven by a reduction in the surface energy of the thin film and, strictly depends on the interface energy between the thin film and the underlying substrate [18].…”