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In recent years, research on atomically thin van der Waals layered crystals has become a central topic in condensed matter physics. The investigation of their optical properties is a very active ...area of research. It has an important presence in the development of new photonic components, optical devices, and the enhancement of existing functionalities. In this research work, we present an experimental analysis of the optical properties of three prospective examples of layered systems by spectroscopic ellipsometry. The obtained results are of great importance for the development of photo-responsive devices in the visible range, as well as for potential applications in optoelectronics and nanotechnologies.
Abstract
Surface-enhanced Raman spectroscopy (SERS) is a potent and highly selective tool to chemically identify and determine the structure of molecules and materials. However, the large ...biomolecules and living cells are still difficult to study using modern SERS-substrates. Here we present a new approach to the geometry of the surface of plasmon nanostructures (cellular surfaces), which makes it possible to efficiently work with volumetric objects as cells or organelles. We use the scanning Raman microscope to map the SERS from the specially prepared microcapsules formed with a Layer-by-Layer deposition method and with built-in Raman tags (Indocyanine green). It demonstrated the possibility to detect SERS signal from Indocyanine green in microcapsules located in cavities, while the signal from the Raman dye in microcapsules located on a flat surface is not detected. The obtained results can be useful in biosensors applications.
Ultra-thin metal films will form the basis of next-generation optoelectronics. However, characterization of their performance requires consideration of nanocrystalline structure and analysis of local ...optical and electrical properties. In present study, we use scanning near-field optical microscopy (SNOM) for nanoscale probing of optical conductivity of ultrathin metal films. We obtained surface maps of scattered near-field signal for gold films grown on monolayer graphene and MoS2 films as well as on a pure Si/SiO2 substrate. These results clearly demonstrate the difference in generated optical responses and can be used in the development of various devices utilizing ultrathin metal films.
Graphene oxide (GO) is a promising platform to realize immobilization matrices for plasmonic biosensors. Here, we discuss various aspect of the deposition of GO thin films, their optical properties, ...and the influence of GO linking layers on biosensing sensitivity. Using spectroscopic ellipsometry, we obtain dielectric functions of thin GO films deposited by spray-coating in the visible and near-infrared ranges. In addition, we demonstrate that the optimization of GO linking layers may sufficiently increase the sensitivity of SPR biosensing.
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Quasi one-dimensional materials are technologically very important due to their extraordinary properties. The properties are enhanced when these materials are exfoliated into single or few layers. ...In this work, we present the laser etching of TiS
3
nanoribbons synthesized by chemical vapor transport technique. The experiments were carried out using the TiS
3
nanoribbons with thicknesses ranging from 100 to 150 nm. These nanoribbons were transferred on a silicon substrate via mechanical exfoliation technique prior to the laser treatment for the etching process followed. The resulting etching depth was in the range of 20–25 nm with no oxidation. Through the experiments, it was found that the etching depth was independent of the initial thickness of the nanoribbons, which suggests that if samples had a smaller initial thickness, a monolayer can be obtained. We also observed significant (up to 3–4 nm) improvement of the surface roughness of the etched samples, which makes the laser etching technique promising for the development of flexible, efficient, and reliable optoelectronic devices.
Hybrid graphene-nanometallic structures Volkov, V S; Yakubovsky, D I; Stebunov, Y V ...
Journal of physics. Conference series,
09/2018, Letnik:
1092, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The development of functional hybrid nanomaterials based on graphene and metal nanostructures is currently the subject of intense research interest. In this study we discuss different aspects ...relevant to growth morphology, properties (optical, electrical, and structural), as well as the nanoscale architecture of hybrid graphene-nanometallic structures based on graphene as a multifunctional platform. The peculiarities of growth kinetics of thin gold and copper films on graphene are analysed (by use of the variety of experimental methods) and compared. It is shown that the presence of graphene affects strongly the optical, electrical, and structural properties of thin metal films.
In the present study, a new method for analyzing the dielectric functions in dependence with the thickness of ultra-thin gold films is proposed. The reliability of the method is carefully verified ...through the correlation of optical properties and structural morphology of gold films at thicknesses around the percolation threshold (from 2 to 20 nm). The optical characterization of deposited films is performed in visible and NIR regions (300-1500 nm) by a spectroscopic ellipsometry along with transmission spectra measurements at normal incidence. Fitting of the ellipsometric data allows one to calculate the effective complex dielectric function of cluster-like and continuous films of different mass-equivalent thickness. Surface morphology of the films is analysed by scanning electron microscopy.
In present study, we develop an effective and universal technique for retrieving dispersion of bulk and monolayer TMDs from spectroscopic ellipsometry measurements. The basis of the method is ...excitonic nature of the dispersion. In addition, we demonstrate beneficial influence of annealing on optical properties of MoS2.
Fabrication of continuous ultra-thin (<10 nm) and ultra-smooth gold films on different substrates is reported. Using a variety of electrical, optical and structural characterization techniques, we ...show that monolayer MoS2 can be superior to more conventional adhesion/seeding layers as an optical substrate for realizing ultra-thin gold films. Our results show that optical losses in ultrathin gold films increase with decreasing thickness due to the fine-grained structure and the presence of a small number of voids, however, they exhibit metallic properties down to a thickness of 3-4 nm.
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