Plasmon-enhanced vibrational spectroscopy, including surface-enhanced infrared absorption spectroscopy (SEIRA) and surface-enhanced Raman scattering (SERS), has attracted great attention in molecular sensing and nano-spectroscopy. In this work, we present a facile in situ-controlled method for the chemical synthesis of patchy SiO₂@Au core-shell nanoparticles with multiple plasmonic nanogaps. The multiple sizes and shapes of Au nano-islands on patchy Au nanoshells and their plasmonic coupling exhibit broadband resonances ranging from the near infrared (NIR) region to the middle infrared (MIR) region, making patchy Au particles ensemble suitable for both SEIRA and SERS applications. In the SEIRA application, we demonstrate in situ and real-time monitoring of monolayer of reduced glutathione molecules (GSH) adsorbed on the plasmonic Au surface. By using GSH as the molecular linker, we also demonstrate in situ detection of trace amount of mercuric ions in water at nanomolar level. In the SERS application, we show the applicability of patchy Au nanoparticles for SERS at 785 nm excitation.

We demonstrate fabrication of higher-order three-dimensional layer stack nanostructure for molecular detection and electrode. Here, we develop two novel surface enhanced Raman scattering (SERS) platform with three-dimensional nanostructure using competitive self-assembly between convective aggregation and dielectrophoresis. Appropriate conditions are able to provide the higher-order layer stack nanostructure onto the desired area on demand. We measured the photoluminescence (PL) characters of the higher-order layer stack nanostructure. The local surface plasmon resonance is induced on the surface of the higher-order layer stack nanostructure, resulting the enhancement of PL and SERS-activity. We achieved the in situ highly sensitive SERS of analyte using the fabricated higher-order layer stack nanostructure. Our method enables the development of active functional control devices for in situ SERS and solar cell power battery.

The study of metal nanoparticles (NPs) is challenging for the control of the light matter interaction phenomena. In this context, our work is focused on optical characterization and modeling of polymer thin films layers with inclusions of previously chemically synthesized NPs. Through the presence of metallic NPs in polymer thin films, the optical properties are assumed to become tunable. Thin film layers with inclusions of differently shaped and sized silver NPs, such as nanospheres and nanoprisms, are optically characterized to get the scattering, the reflection and the absorption of the layers. One step and two step seed based methods of silver ions reduction are used for the chemical synthesis of nanospheres and nanoprisms. The plasmonic resonance peaks of these colloidal solutions range from 360 to 1300 nm. A poly vinyl pyrrolidone (PVP) polymer matrix is chosen for its light non-absorbing and NP-stabilizing properties. Knowledge on the shape and size of the NPs embedded in the spin coated layers is obtained by transmission electron microscopy (TEM) imaging. The optical properties include spectrophotometry and spectroscopic ellipsometry (SE) measurements to get the reflectance, the transmittance, the absorptance and the optical indices n and k of the heterogeneous layers. A redshift in absorption is measured between deposited nanospheres and other shaped NPs. FDTD simulations allow calculation of far and near field properties. The visualization of the NP interactions and the electric field enhancement, on and around the NPs, are studied to improve the understanding of the far field properties.

Metamaterials have been of great interest owing to multifarious technological applications. Among various applications of scientific need, the perfect absorber kind of property of metamaterials remains prudent. Within the context, this investigation describes the filtering/absorber applications of metasurfaces comprised of columnar nanorods of gold having circular and elliptical cross-sections. The spectral features of such absorbers are investigated in terms of absorptivity in the visible to infrared (IR) regimes. The results indicate of almost perfect absorption corresponding to certain wavelengths in the IR span. Also, multiple absorption peaks would determine the filtering characteristics of the structures under consideration. It has been found that the absorber having circular nanorods exhibits better performance than the one with elliptical nanorods in terms of the magnitude/smoothness of absorption peaks in the entire electromagnetic spectral region of interest; the case of elliptical nanorods makes the absorption spectra to yield too much of flickers in the IR range of wavelength.

Metal nanohelix arrays have been fabricated using glancing angle deposition. Comparing with method of substrate patterning, nanohelices with average arm width of 32 nm, pitch length of 34 nm and radius of curvature around 12.5 nm grew on a regular seeded layer with period of 79 nm and average seed diameter of 14 nm. In order to mass produce metal nanohelices, smooth substrates were adopted to deposited nanohelix arrays. Due to shadowing effect achieved under substrate cooling, the silver and gold nanohelix arrays could be grown successfully on smooth substrates by well controlling the substrate spin rate with respect to the deposition rate. In this work, the thickness of deposition monitored by quartz monitor was kept at 0.3 nm/s. The substrate was cooled to a low temperature around -10oC. The average arm width, pitch length, radius of curvature and spacer between nanohelices vary with deposition angle are investigated here. The morphology of nanohelix varies with different deposition angles (from 86o to 80o) were also to be investigated. In this work, the average space between adjacent nanohelices and radius of curvature were reduced and increased by increasing the deposition angle, respectively. The average pitch of each nanohelix array was low dependent on the deposition angle. The overlap effect occurs between adjacent nanohelices and the gaps between nanohelices support local field enhancement. The area associated local field enhancement called hot spots. Surface-enhanced Raman scattering (SERS) signals from nanostructured thin films were measured and compared with near-field simulations.

Various approaches for the preparation of nanostructures with dimension on macroscopic areas are known. In contrast to cost-intensive top-down lithographic techniques, various bottom-up methods based on ion beam technologies to form large arrays of nanostructured surfaces are well established. In principle, it can be distinguished between two routes at the preparation of nanostructures by low-energy ion bombardment sputtering.

The destructive route is characterized that under certain conditions, given by the self-organization processes, the ion beam induced erosion process can lead to the formation of e.g. well-ordered Si nanostructures like dots or ripples on the surface. Using a constructive route, i.e. glancing angle deposition by ion beam sputtering, sculptured thin films consisting of various nanostructures of several shapes, such as inclined and vertical columns, screws, and spirals, were deposited on Si substrates. It will be shown that morphology, shape, and diameter of the structures are influenced and can thus be controlled by adjusting various deposition parameters, including substrate temperature and ratio of substrate rotational speed to film deposition rate.

A scalable nanofabrication technique for chiral metamaterials is presented, which combines the dynamic shadowing growth and self-assembled nanosphere monolayers, and is also known as nanosphere shadowing lithography. We have developed two strategies based on nanosphere shadowing lithography to prepare chiral nanostructures. The first strategy is to create a quasi-three-dimensional single-layer fan-shaped chiral nanostructure on nanospheres with one plasmonic material. The second strategy is to create three-dimensional multi-layers helical nanostructures with one plasmonic material and one dielectric material. Both strategies can produce large-area chiral nanostructures with strong chiral optical response, which makes nanosphere shadowing lithography suitable for producing chiral metamaterial based devices such as an ultrathin narrow-band circular polarizer.

Functional assemblies of materials can be realized by tuning the work function and band gap of nanomaterials by rational material selection and design. Here we demonstrate the structural assembly of 2D and 3D nanomaterials and show that layering a 2D material monolayer on a 3D metal oxide leads to substantial alteration of both the surface potential and optical properties of the 3D material. A 40 nm thick film of polycrystalline NiO was produced by room temperature rf-sputtering, resulting in a 3D nanoparticle assembly. Chemical vapor deposition (CVD) grown 10-30 μm WS₂ flakes (2D material) were placed on the NiO surface using a PDMS stamp transfer technique. The 2D/3D WS₂/NiO assembly was characterized using confocal micro Raman spectroscopy to evaluate the vibrational properties and using Kelvin probe force microscopy (KPFM) to evaluate the surface potential. Raman maps of the 2D/3D assembly show spatial non-uniformity of the A_1g mode (~418 cm^-1) and the disorder-enhanced longitudinal acoustic mode, 2LA(M) (~350 cm^-1), suggesting that the WS2 exists in a strained condition on when transferred onto 3D polycrystalline NiO. KPFM measurements show that single layer WS₂ on SiO₂ has a surface potential 75 mV lower than that of SiO₂, whereas the surface potential of WS₂ on NiO is 15 mV higher than NiO, indicating that WS₂ could act as electron donor or acceptor depending on the 3D material it is interfaced with. Thus 2D and 3D materials can be organized into functional assemblies with electron flow controlled by the WS₂ either as the electron donor or acceptor.

Technological developments in laser technology require advancements in optical components. Such demand is particularly important in UV spectral region. Antireflection coatings (AR) and waveplates as a widely used optical elements were produced based on glancing angle deposition (GLAD) method. Superior optical performance was measured for AR thin films. Broadband and broad-angle antireflection coatings were manufactured by using multilayer system when changing the refractive index profile by varying the porosity of material. SiO₂, Al₂O₃ and LaF₃ materials were used for formation of waveplates for UV region. An investigation of optical and resistant performance were conducted. All materials showed optical losses at the wavelength of 355 nm. Possible technological solutions are presented and investigated.

In optics, artificially structured nanomaterials act as effective media whose complex refractive index may be ad-hoc designed for applications in multilayer coatings.

Nano metal fluorides are appropriate materials for different applications e.g. heterogeneous catalysis, ceramic materials for laser applications and antireflective layers on glass, respectively. An easy way to synthesize such nano metal fluorides is the fluorolytic sol-gel synthesis which was developed some few years ago for HS-AlF₃ ^[1] and MgF₂.^[2]

CaF₂ exhibits similar optical properties as MgF₂, and thus, is a promising candidate for antireflective (AR) coatings. That means, CaF₂ exhibits a lower refractive index (n₅₀₀ = 1.44) as compared to common soda lime glass (n₅₀₀ = 1.53). Hence, we present an easy synthesis approach toward nanoscaled CaF₂ sols to fabricate finally AR-CaF₂ films by dip coating. Irrespective of the choice of the calcium precursor, the CaF₂ films are porous in comparison to thin dense CaF₂ films which are generated by physical vapor deposition. The characterization of CaF₂ films was performed by different analytical methods like HR-SEM, XPS, EDX, EP (ellipsometric porosimetry), DLS (dynamic light scattering) and CA (contact angle measurement). Beside the good optical and mechanical properties, we have investigated the surface properties of CaF₂ films on glass and silicon wafer e.g. surface morphology with elemental composition, open porosity, zeta potentials at the surfaces as well as the free energy of interaction between water and the CaF₂ film.

In this presentation, we demonstrate that high refractive index materials such as β-FeSi₂ and/or chromogenic materials such as VO₂ are the key to control solar and thermal radiations. β-FeSi₂ is known as an eco-friendly semiconductor and for sputtered polycrystalline β-FeSi² thin films, we recently found that λ~0.3 in IR region, while n is higher than 5. On the other hand, another interesting optical property of β-FeSi₂ is that both n and k are considerably high in visible to NIR region ( λ ≤ 1.55 μm). Using these optical properties in IR and VIS, we designed multilayers consisting of β-FeSi₂/SiO₂/β-FeSi₂/W, where the upper β-FeSi₂ layer absorbs VIS and NIR (λ ≤ 1.0 μm) and the bottom β-FeSi₂ layer/W absorbs IR (1.0 ≤ λ ≤2.0 μm). The optimized multilayers absorb more than 90% of solar energy and the eminence at 450 °C is lower than 10%. The perfect absorbers with high refractive index layers are useful for applications to solar selective absorbers for solar thermal power generation and spectrally selective thermal emitters for thermophotovoltaic power generation, IR heaters, radiation cooling. Replacing one of β-FeSi₂ layers with a chromogenic material allows active control of solar and thermal radiation. In the presentation, we also demonstrate the active perfect absorbers including a VO₂ layer in NIR region.

Breaking optical diffraction limit is one of the most important issues needed to be overcome for the demand of high-density optoelectronic components. Here, a multilayered structure which consists of alternating semiconductor and dielectric layers for breaking optical diffraction limitation at THz frequency region are proposed and analyzed. We numerically demonstrate that such multilayered structure not only can act as a hyperbolic metamaterial but also a birefringence material via the control of the external temperature (or magnetic field). A practical approach is provided to control all the diffraction signals toward a specific direction by using transfer matrix method and effective medium theory. Numerical calculations and computer simulation (based on finite element method, FEM) are carried out, which agree well with each other. The temperature (or magnetic field) parameter can be tuned to create an effective material with nearly flat isofrequency feature to transfer (project) all the k-space signals excited from the object to be resolved to the image plane. Furthermore, this multilayered structure can resolve subwavelength structures at various incident THz light sources simultaneously. In addition, the resolution power for a fixed operating frequency also can be tuned by only changing the magnitude of external magnetic field. Such a device provides a practical route for multi-functional material, photolithography and real-time super-resolution image.

The extraordinary progresses in the design and realization of structures in inorganic or organic thin films, whether or not including nanoparticles, make it possible to develop devices with very specific properties. Mastering the links between the macroscopic optical properties and the opto-geometrical parameters of these heterogeneous layers is thus a crucial issue. We propose to present the tools used to characterize and to model thin film layers, from an optical point of view, highlighting the interest of coupling both experimental and simulation studies for improving our knowledge on the optical response of the structure. Different examples of studies are presented on CIGS, Perovskite, P3HT:ZnO, PC70BM, organic layer containing metallic nanoparticles and colored solar cells.

In this work we characterize the thermal conductivity properties of nanoprous ‘black silicon’ (bSi). We fabricate the nanoporous bSi using the metal assisted chemical etching (MACE) process utilizing silver (Ag) metal as the etch catalyst. The MACE process steps include (i) electroless deposition of Ag nanoparticles on the Si surface using silver nitrate (AgNO₃) and hydrofluoric acid (HF), and (ii) a wet etch in a solution of HF and hydrogen peroxide (H₂O₂). The resulting porosity of bSi is dependent on the ratio of the concentration of HF to (HF + H₂O₂); the ratio is denoted as rho (ρ). We find that as etch time of bSi increases the thermal conductivity of Si increases as well. We also analyze the absorption of the bSi samples by measuring the transmission and reflection using IR spectroscopy. This study enables improved understanding of nanoporous bSi surfaces and how they affect the solar cell performance due to the porous structures’ thermal properties.

Three theoretical studies were undertaken, each based on the Bruggeman homogenization formalism and each involving homogenized composite materials (HCMs) comprising active component materials. It was found that: (i) HCMs can exhibit higher degrees of amplification than are exhibited by the HCM’s component materials; (ii) anisotropic HCMs can simultaneously exhibit plane-wave amplification for certain propagation directions and plane-wave attenuation for other propagation directions; and (iii) for isotropic chiral HCMs, left-circularly polarized fields may be amplified while right-circularly polarized fields may be simultaneously attenuated (or vice versa) in any propagation direction.

A scaling analysis of the extraordinary transmission by subwavelength holes is provided. The structure under study is a lamellar grating. The grating can be described by homogeneous permittivity and permeability tensors. The permeability is dispersive and the peaks of transmission result from a Bragg condition.

Bloch surface waves (BSWs) in periodic dielectric multilayer structures with surface defect have been extensively studied. However, it has recently been recognized that quasi-crystals and aperiodic dielectric multilayers also support Bloch-like surface waves (BLSWs). In this work, we numerically show the existence of BLSWs in Fibonacci quasi-crystals and Thue-Morse aperiodic dielectric multilayers using the prism coupling technique. We compare the surface field enhancement and penetration depth of BLSWs in these structures with that of BSWs in their periodic counterparts.

Surface waves of different types can be compounded when a homogeneous layer is sandwiched between two half spaces filled with dissimilar periodically non-homogeneous dielectric materials and the intermediate layer is sufficiently thin. We solved the boundary-value problem for compound waves guided by a layer of a homogeneous and isotropic (metal or dielectric) material sandwiched between a structurally chiral material (SCM) and a periodically multi-layered isotropic dielectric material. We found that the periodicity of the SCM is crucial to excite a multiplicity of compound guided waves with strong coupling between the two interfaces.

Chiral sculptured thin films (STFs) were grown using the asymmetric serial-bideposition (ASBD) technique, whereby (i) two sub-deposits of unequal heights are made separated by a substrate rotation of 180° about the central normal axis, and (ii) consecutive subdeposit pairs are separated by a small substrate rotation δ on the order of a few degrees. Eight samples were prepared with sub-deposit heights in ratios of 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 5:1, 7:1, and 9:1. A finely ambichiral STF was also grown. All nine samples were grown with the same vapor flux direction and to have 10 periods with the same thickness. The spectrums of all eight circular remittances of every sample were measured over a wide range of incidence angle θ_inc. Red-shifting and narrowing of the circular Bragg regime was observed with increasing sub-deposit-height ratio for all values of θ_inc, arriving at a limit with the 9:1 sample. The finely ambichiral sample has a circular Bragg regime similar to that of the 9:1 sample, but the latter exhibits much better discrimination between incident left circularly polarized light and right circularly polarized light than the former.

An asymmetric propagation in a photonic diode-like heterostructure is studied theoretically. The heterostructure is composed by two distinct planar waveguides with low and high refractive indices, respectively. The physical mechanism exploited to obtain an asymmetric propagation is based on the matching of eigenmodes. Considering the Transversal Magnetic (TM) polarization, it is found that at a specific frequency on the low index waveguide only the first even mode (TM_e1) exists while for the high index waveguide two modes are allowed, the TM_e1 and the first odd mode (TM_o1). We report an asymmetric transmission through the junction of waveguides. On the one hand, it is observed that the TM_e1 mode is able to propagate from the low into the high index waveguide and vice-versa. On the other hand, the TM_o1 mode cannot pass from the high into the low index waveguide.

The photo conversion efficiencies of the 1st and 2nd generat ion photovoltaic solar cells are limited by the physical phenomena involved during the photo-conversion processes. An upper limit around 30% has been predicted for a monojunction silicon solar cell. In this work, we study 3rd generation solar cells named rectenna which could direct ly convert visible and infrared light into DC current. The rectenna technology is at odds with the actual photovoltaic technologies, since it is not based on the use of semi-conducting materials.

We study a rectenna architecture consist ing of plasmonic nano-antennas associated with rectifying self assembled molecular diodes. We first opt imized the geometry of plasmonic nano-antennas using an FDTD method. The optimal antennas are then realized using a nano-imprint process and associated with self assembled molecular diodes in 11- ferrocenyl-undecanethiol. Finally, The I(V) characterist ics in darkness of the rectennas has been carried out using an STM. The molecular diodes exhibit averaged rect ification ratios of 5.

Making progress in recent years, with the technology of the grating, the grating period can be reduced to shrink the size of the light coupler on a waveguide. The working wavelength of the light coupler can be in the range from the near-infrared to visible. In this study , we used E-gun evaporation system with ion-beam-assisted deposition system to fabricate bottom cladding (SiO2), guiding layer (Ta2O5) and Distributed Bragg Reflector(DBR) of the waveguide on the silicon substrate. Electron-beam lithography is used to make sub-wavelength gratings and reflector grating on the planar waveguide which is a coupling device on the guiding layer. The best fabrication parameters were analyzed to deposit the film. The exposure and development times also influenced to fabricate the grating quality. The purpose is to reduce the device size and enhance coupling efficiency which maintain normal incidence of the light . We designed and developed the device using the Finite-Difference Time-Domain (FDTD) method. The grating period, depth, fill factor, film thickness, Distributed Bragg Reflector(DBR) numbers and reflector grating period have been discussed to enhance coupling efficiency and maintained normal incidence of the light. According to the simulation results, when the wavelength is 1300 nm, the coupling grating period is 720 nm and the Ta2O5 film is 460 nm with 360 nm of reflector grating period and 2 layers of Distributed Bragg Reflector, which had the optimum coupling efficiency and normal incidence angle. In the measurement, We successfully measured the TE wave coupling efficiency of the photoresist grating coupling device.

We have established ALD methodology to synthesize nanocomposite coatings comprised of conducting, metallic nanoparticles embedded in an amorphous dielectric matrix. These films are nominally composed of M:Al2O3 where (M= W, Mo, and Ta) and are prepared using alternating exposures to trimethyl aluminum (TMA) and H2O for the Al2O3 ALD and alternating MF6/Si2H6 exposures for the metal ALD. By varying the ratio of ALD cycles for the metal and the Al2O3 components during material growth, we can tune precisely the various material properties such as microstructure, electrical, optical and chemical properties. The resistance of these coatings can be controlled over a very broad range (e.g. 1e11-1e4 Ohm-cm) and these films exhibit Ohmic behavior and resist breakdown even at high electric fields of <1e7 V/m. Moreover, the self-limiting nature of ALD allows us to grow these films inside of high aspect ratio substrates and on complex 3D surfaces. We have exploited these nanocomposite coatings for applications such as functionalization of large-area microchannel plates suitable for area photodetectors, charge drain coatings for electron optic MEMS devices (Digital Pattern Generation chips) for maskless reflection electron beam lithography system, protective coatings for Li-ion battery cathodes and solar selective absorber coating for high temperature concentrated solar power (CSP). Here we will discuss the ALD in-situ growth study, various nanocomposite material characterizations, and some of these applications.

This paper describes preparation and characterization of the optically-transparent and electrically conducting thin films of fluoride-doped tin dioxide (FTO) one-dimensional nanostructures and features of the purpose-built, novel and advanced version of spray pyrolysis technique, known as Rotational, Pulsed and Atomized Spray Pyrolysis. This technique allows perfect and simple control of morphology of the nanostructures of FTO layer by adjusting the spray conditions. Effect of the different additives on crystal morphology and texture of the 1-dimensional (1-D) nanostructured FTO thin films is studied. Vertically aligned and well separated nanotubes are easily fabricated using propanone and ethanol as additives. We suggest that propanone additive plays a role to form vertically aligned nanotubes with (101) preferential orientation while (110) face is the predominant plane of well separated nanotubes with ethanol additive. The conductivity of the 1-D nanostructured thin films are also enhanced using the commercial FTO glasses as a substrate.

For efficient plasmonic MIM structures in fabrication of optical nano-probe tip for scanning near-field microscope (SNOM), an experimental study of thin film fabrication of titanium nitride (TiN) has been started by pulsed laser deposition (PLD) with 3rd harmonic (355nm) pulses of high-power Nd:YAG laser. Inside a TMP-pumped UHV chamber, a TiN powder sintered body has been irradiated with the UV laser pulses (3.3 nsFWHM, 10Hz, up to 340mJ/ pulse on target) at different intensities and incident angles. The deposited films on glass slide or silicon wafer has been analyzed by X-ray diffractometer (XRD), UV-Vis spectrophotometer, scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). Previously-reported PLD fabrication experiments for TiN film used a titanium (Ti) target with several gas species including nitrogen. The laser-produced Ti plasma with an appropriate condition had a chemical reaction with nitrogen molecules, and the resultant TiN film was deposited on a substrate. While on the other hand, this study has significant features of (1) PLD target made of crystalline powder sintered body and (2) UV laser pulses having temporally-smoothed gaussian profile by injection-seeding of IR laser diode beam. The very first trial depositions have succeeded to fabricate flat and dense films of a few hundred nm, which were partly covered with debris and cracks. The resultant XRD pattern of film having luster of gold indicated several peaks including 42.6° (200) and 61.8° (220) which correspond to crystal structure of TiN. The electron configuration in the PLDed TiN film is studied using XPS.

Pyroelectric photoresponse of aqueous spray deposited thin films containing BaTiO₃ nano-crystals is reported. X-ray diffraction data indicate the presence of hexagonal BaTiO₃ nano-crystals with ~20 nm crystalline domains in a matrix of some as yet unidentified nano-crystalline material. When the film is annealed at 600 C, the X-ray pattern changes significantly and indicates a conversion to one of the non-hexagonal phases of BaTiO₃ as well as a complete change in the matrix. With suitable amplifier, the measured photoresponse was 40V/W. Ferroelectric hysteresis on a film with significant presence of hexagonal BaTiO₃ shows saturated polarization which is about 5-times smaller than for the bulk tetragonal phase. A potential application is a patternable infrared detector for photonic and plasmonic devices, such as chip-scale spectral sensors.

Ionized nitrogen doped Si-C multi-layer thin films used to increase the oxidation resistance of carbon have been obtained by Thermionic Vacuum Arc (TVA) method. The 100 nm thickness carbon thin films were deposed on silicon or glass substrates and then seven N doped Si-C successively layers on carbon were deposed. To characterize the microstructure, tribological and electrical properties of as prepared N-SiC multi-layer films, Transmission Electron Microscopy (TEM, STEM), Energy Dispersive X-Ray Spectroscopy (EDXS), electrical and tribological techniques were achieved. Samples containing multi-layer N doped Si-C coating on carbon were investigated up to 1000°C. Oxidation protection is based on the reaction between SiC and elemental oxygen, resulting SiO₂ and CO₂, and also on the reaction involving N, O and Si-C, resulting silicon oxynitride (SiN_xO_y) with a continuously vary composition, and because nitrogen can acts as a trapping barrier for oxygen. The tribological properties of structures were studied using a tribometer with ball-on-disk configuration from CSM device with sapphire ball. The measurements show that the friction coefficient on the N-SiC is smaller than friction coefficient on uncoated carbon layer. Electrical conductivity at different temperatures was measured in constant current mode. The results confirm the fact that conductivity is greater when nitrogen content is greater. To justify the temperature dependence of conductivity we assume a thermally activated electrical transport mechanism.

Phototherapy makes use of different radiation sources, and the treatment of hyperbilirubinemia the most common therapeutic intervention occurs in the neonatal period. In this work we developed an organic optoelectronic sensor capable of detecting and determining the radiation dose rate emitted by the radiation source of neonatal phototherapy equipment. The sensors were developed using optically transparent substrate with Nanostructured thin film layers of Poly(9-Vinylcarbazole) covered by a layer of Poly(P-Phenylene Vinylene). The samples were characterized by UV-Vis Spectroscopy, Electrical Measurements and SEM. With the results obtained from this study can be developed dosimeters organics to the neonatal phototherapy equipment.

Self-organization offer cost-efficient and easily scalable way to nanopattern polymer surfaces for various applications ranging from medical use to sensing applications. For example poly-L-lactic acid can be modified either by metal sputtering and/or plasma discharge to form ripple-like structures after annealing with size and regularity highly dependent on processing variables. Such samples have enhanced biocompatibility and as such they are promising substrates for use as various implants. Another example is annealing of polyethersulfone film modified by metal sputtering that causes coalescence of metal layer into separated metal nanoclusters. This structure exhibit localized surface Plasmon resonance, which can be used for example in Surface enhanced Raman spectroscopy.

Porous antireflective thin films, prepared of nanoscopic MgF₂ sols, exhibit a low refraction index and are useful for various optical applications. Due to their porosity, film stability and durability suffer from mechanical abrasion and water solubility, respectively. Hence, we present approaches of improved mechanical stability of MgF₂ layers induced by chloride addition. Antireflective (AR) films were produced by dip-coating followed by thermal treatment. Afterwards, film stability and environmental durability was strained by crockmeter and water stability tests, respectively. In comparison to films prepared from chloride-free MgF₂ sols, chloride mingled sols form coatings with increased mechanical stability and a lower solubility.

A novel mechanochromic elastomer based on silicone rubber and coumarin 6 dye have been prepared with various concentrations of the dye ranges from 2wt.% to a maximum of 5wt.% by solution mixing technique. After evaporating the solvent, cured samples were prepared as thin films using compression molding at 170° C. The optimum composition of the dye in rubber composites was determined based on the mechanochromic performance characterized with ultraviolet/visible (UV/Vis) spectrometer, x-ray diffraction (XRD) and spectrofluorometer (FL). The UV/Vis spectrometer monitors the dye aggregation in polymer film during the tensile deformation. The XRD monitors the change in size of dye aggregates. The FL monitors the optical response during tensile deformation due to the re-arrangement of dyes. As increasing a mechanical deformation to the polymeric composite film, UV/Vis absorption intensity was decreased and the FL emission wavelength was moved to decrease wavelength because of breaking dye aggregations. Also, XRD intensity peak was decreased, which dye aggregations were broken after mechanical deformation.

Various examples are reported of chromogenic materials composed of a functional dye covalently linked to the polymer chains or physically dispersed in the continuous macromolecular matrix, the latter appears to be a more sustainable route for the industrial scale-up of these materials. In this study, a mechanochromic elastomer was prepared by physically dispersing dye materials into a rubber matrix by solution mixing technique. The employed rubber is natural rubber (NR). The NR was chosen because of its ability of strain-induced crystallization. Perylene diimide I is selected after considering its aggregachromic nature and affinity with rubber matrix. The optimum composition of dye in rubber composites was determined based on the mechanochromic performance characterized with ultraviolet/visible (UV/Vis) spectrometer, x-ray diffraction (XRD) and spectrofluorometer (FL). The UV/Vis spectrometer and FL monitor the optical responses, such as absorbance and emission property, under tensile deformation due to the breakage of dye aggregates. Spectroscopic analysis with polarization monitors the breakage of dye aggregates and anisotropic property of the sample. The XRD monitors the change in size of dye aggregates. With polarization filtering, the breakage of dye aggregates are clearly observed and anisotropic property of the sample is also confirmed. The XRD results indicate that dye aggregates were broken during stretching because the shear force is applied to dye aggregates.

We report the deposition of nanostructured Cu-Zn-S composite thin films by Successive Ionic Layer Adsorption and Reaction (SILAR) method on glass substrates at room temperature. The structural, morphological, optical, photoluminescence and electrical properties of Cu-Zn-S thin films are investigated. The results of X-ray diffraction (XRD) and Raman spectroscopy studies indicate that the films exhibit a ternary Cu-Zn-S structure rather than the Cu xS and ZnS binary composite. Scanning electron microscope (SEM) studies show that the Cu-Zn-S films are covered well over glass substrates. The optical band gap energies of the Cu-Zn-S films are calculated using UV-visible absorption measurements, which are found in the range of 2.2 to 2.32 eV. The room temperature photoluminescence studies show a wide range of emissions from 410 nm to 565 nm. These emissions are mainly due to defects and vacancies in the composite system. The electrical studies using Hall effect measurements show that the Cu-Zn-S films are having p-type conductivity.

The synthesis and deposition of nanoparticles consisting of Cu and Au in a CuSO₄ solution with some kinds of alcohol and electroplating solution containing gold (I) trisodium disulphite under synchrotron X-ray radiation was investigated. The functional group of alcohol plays an important in nucleation, growth and aggregation process of copper and cupric oxide particles. We found that the laboratory X-ray source also enables us to synthesize the NPs from the metallic solution. As increasing X-ray exposure time, the full length at half width of particle size distribution is broader and higher-order nanostructure containing NPs clusters is formed. The surface-enhanced Raman scattering (SERS) of 4, 4'-bipyridine (4bpy) in aqueous solution was measured using higher-order nanostructure immobilized on silicon substrates under systematically-varied X-ray exposure. This demonstration provide a clue to develop a three-dimensional printing and sensor for environmental analyses and molecular detection through simple SERS measurements.

When Palladium film is exposed to hydrogen, it becomes palladium hydride. A change in the complex permittivity of the metal film results in a change of the optical properties that depends on hydrogen concentration. Ellipsometry is the technique of choice to measure the optical constants prior and during hydrogenation. Sensors are then usually designed and optimized to measure changes in transmittance or reflectance of the palladium films. Films of different thicknesses have been realized and tested to verify potential applications in hydrogen sensing by studying the optical response prior, during and after hydrogenation, to assess in particular the reversibility of the process. Within this work a deep analysis carried out by x–ray reflectance (XRR) shows that during hydrogenation the films change also their thickness, and the amount has been assessed for a specific hydrogen concentration. Ellipsometric measurements have been therefore corrected taking into account such variation to determine the optical constants. Such structural property of the palladium hydride may be exploited in surface plasmon resonance transducers, which are sensitive also to the change of the sensing film thickness during detection.

Physical and optical characterization of thin films doped with Au Nanoparticles onto a silica substrate is presented. Films were prepared through sol-gel process, by using Au nanoparticles immersed in lipoic acid as dopant by means of hydrolysis and acid catalyzed reaction of tetraethyl-orthosilicate. The surface was characterized by SEM and AFM microscopies. Z-scan technique was used to measure nonlinear optical properties as nonlinear absorption and refraction indexes, using two different wavelengths. At 633 nm it was possible to observe nonlinear absorption only but at 514 nm both nonlinear properties were observed.

Structure and optical properties of amorphous diamond-like carbon (a-C: H) thin films modified with Ag, Ti and Ag + Ti metal impurities are studied. The films were prepared by ion-plasma magnetron sputtering of combined polycrystalline graphite and metal target in the mixture of Ar and CH₄ gases. AFM, SEM and TEM methods show that a-C:H<Ag+Ti> films are heterogeneous, nanostructured and characterized by the presence of silver nanoclusters on the surface sized ~ 60 nm and both Ti and Ag nanoclusters with a mean size ~ (2 ÷ 3) nm in the bulk of films. It was found that in a- C:H<Ag+Ti> films as well as in a-C:H<Ag> films plasma resonance absorption due to excitation of surface plasmons in silver nanoclusters in the visible region of spectrum takes place. Intensity of the resonance absorption in the a- C:H<Ag+Ti> films increases with increase in concentration of silver. The results are important for produce of nanomaterials with nonlinear optical properties based on the amorphous diamond-like carbon films containing metal nanoclusters.

Multiple surface-plasmon-polariton (SPP) waves are guided by the interface of a metal and a chiral sculptured thin film (STF) at a single wavelength. Spatially multiplexed 4-quadrant chips comprising a lanthanum-fluoride chiral STF embedded with a silver-nanoparticle layer were deposited atop an aluminum-coated glass substrate, each quadrant functioning as an autonomous sensor. The void regions of the chiral STF in each quadrant were in filtrated with sucrose solutions of increasing molarity and deployed in a prism-coupled surface-multi-plasmonics-resonance- imaging (SMPRI) machine. The angular locations of the SPP-wave modes shift as the molarity of the fluid increases, thus demonstrating simultaneous sensing of fluids via SMPRI.

Lead magnesium niobate-lead titanate (PMN-PT) is an important and high performance piezoelectric and pyroelectric relaxor material having wide range of applications in infrared sensor devices. Present work studies the fabrication and dielectric characteristics of PMN-PT in the bulk form. The PMN-PT bulk material was prepared in sol-gel method and subsequently irradiated with heavy ion oxygen. The materials were analyzed and determined that the relaxorferroelectric material indicated changes in its dielectric constant and pyroelectric coefficient after irradiation. Due to the radiation fluent of 1×10¹⁶ ions/cm², the dielectric constant of the material increased uniformly, while its pyroelectric coefficient showed a sharp increased to the value of 5×10^-9 μC/cm² °C with increase in temperature. Its dielectric constants showed increase in values of 527 μC/cm² °C at 50°C, 635 μC/cm2 °C at 60°C and 748 μC/cm² °C at 70°C. Properties such as the material impedance, admittance and modulus were investigated for changes in properties which became evident after irradiation.

Optical biosensors have become a powerful alternative to the conventional ways of measurement owing to their great properties, such as high sensitivity, high dynamic range, cost effectiveness and small size. Choice of an optical biosensor's materials is an important factor and impacts the quality of the obtained spectra. Examined biological objects are placed on a cover layer which may react with samples in a chemical, biological and mechanical way, therefore having a negative impact on the measurement reliability. Diamond, a metastable allotrope of carbon with sp³ hybridization, shows outstanding properties such as: great chemical stability, bio-compatibility, high thermal conductivity, wide bandgap and optical transparency. Additionally it possesses great mechanical durability, which makes it a long-lasting material. The protective diamond thin films were deposited on the substrate using Microwave Plasma Assisted Chemical Vapor Deposition (MW PA CVD) system. The surface morphology and roughness was assessed with atomic force microscopy and profilometry. We have performed a series of measurements to assess the biocompatibility of diamond thin films with whole blood. The results show that thin diamond protective layer does not affect the red blood cells, while retaining the sensors high resolution and dynamic range of measurement. Therefore, we conclude that diamond thin films are a viable protective coating for optical biosensors, which allows to examine many biological elements. We project that it can be particularly useful not only for biological objects but also under extreme conditions like radioactive or chemically aggressive environments and high temperatures.