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In this work, we carried out a complex analysis of gold films near the percolation threshold. It was determined how graphene influences the growth of films and which benefits it provides to the substrates for their application in SERS. Gold films were deposited on two types of substrates by electron-beam evaporation and the thickness of these films ranged from 3 to 10 nm. The first type of substrate was silicon with a thin layer of silicon oxide and the second type was the same substrate, with a single layer CVD graphene. The characterization of films was carried out using such experimental methods as scanning electron microscope (SEM), atomic force microscope (AFM), ellipsometry and sheet resistance measurements. SERS measurements of the dye Crystal Violet showed sufficiently large enhancement factor (EF) and also graphene induced photoluminescence quenching was demonstrated. [ABSTRACT FROM AUTHOR]

In the present study, we report on dispersion function over a spectral range of 300 – 1700 nm (i.e. 0.73 – 4.13eV) for CVD-grown full area coverage monolayer WS2 and WSe2 films on SiO2/Si substrates. The result is obtained via the analysis of spectroscopic ellipsometry spectra by virtue of Tauc-Lorentz oscillators, which takes into account that absorption of these materials are attributed to the formation of the excitons. [ABSTRACT FROM AUTHOR]

The performance of metal-based devices is limited by ohmic losses in the metal, which are determined by electron scattering. The structural properties of gold thin films also play an important role in the film quality, which may affect its' optical properties and the overall capability of the device. At the same time, metal films of different thicknesses are needed for different applications and, since these films are polycrystalline, their internal properties and surface roughness can greatly vary from one thickness to another. In this work, we study, using atomic force microscopy and spectroscopic ellipsometry, the structural morphology and optical properties of polycrystalline gold thin films (fabricated by e-beam deposition at a low sputtering rate smooth gold) in the thickness range of 20 - 200 nm. By extracting the real and imaginary dielectric function and the Drude parameter of electron relaxation rate we demonstrate that the optical losses increase mainly when the film thickness gets lower than 66 nm. Our results reveal that the thickness-dependent contribution is inversely proportional to the film thickness. The experimental results are confirmed by the theoretical model, which predicts optical losses based on structure of the gold films. [ABSTRACT FROM AUTHOR]

Carbon allotropes-based nanomaterials possess unique physical and chemical properties including high surface area, the possibility of pi-stacking interaction with a wide range of biological objects, rich availability of oxygen-containing functional groups in graphene-oxide (GO), and excellent optical properties, which make them an ideal candidate for use as a universal immobilization platform in SPR biosensing. Here, we propose a new surface plasmon resonance (SPR) biosensing interface for sensitive and selective detection of small molecules. This interface is based on the GO linking layers deposited on the gold/copper surface of SPR sensor chips. To estimate the binding capacity of GO layers, modification of carboxyl groups to N Hydroxysuccinimide esters was performed in the flow cell of SPR instrument. For comparison, the same procedure was applied to commercial sensor chips based on linking layers of carboxymethylated dextran. [ABSTRACT FROM AUTHOR]

We report on two approaches aimed at increasing the performance of a photoconductive antenna (PCA) due to enhanced optical light confinement in a PCA's gap. The first refers to the use of a high-aspect ratio metal grating maintaining plasmonic guided modes while the second implies an asymmetric dielectric particle combined with a prism on a metal surface to provide a sub-wavelength focusing of a laser beam. We reached a 3000-fold increase in the emitted THz power and a 25-fold THz photocurrent enhancement in a plasmon-assisted PCA; the further increase in both parameters might be reached by optimizing the geometry of the grating. We propose a new curved beam - the photonic hook plasmon that can be realized using the in-plane focusing of the surface plasmon-polariton wave through a dielectric particle. We demonstrate a potential possibility to reach predominantly a sub-wavelength focused and high-intensive beam obtained from the opposite side of the dielectric particle. [ABSTRACT FROM AUTHOR]