Ag Layer Thickness Research Articles

Fiber Optic SPR Sensing Enhancement in NIR via Optimum Radiation Damping Catalyzed by 2D Materials

Fiber optic surface plasmon resonance (FOSPR) sensor with samarium-doped chalcogenide core, polymer clad, Ag layer, and 2D material (graphene and MoS2) monolayer is studied in near-infrared seeking sensitive and accurate determination of malignancies in human liver tissues. The analysis shows that the presence of 2D material significantly catalyzes the optimum radiation damping (ORD) in the FOSPR structure, causing massive increase in its figure of merit (FOM). At ORD, i.e., 803.9-nm wavelength ( $\lambda $ ) and 35.7-nm Ag layer thickness ( $d_{m}$ ), the FOM of graphene-based FOSPR sensor races to 6904.012 RIU −1. Similarly, at $\lambda = 1099.35$ nm and $d_{m} = 29.8$ nm, MoS2-based FOSPR sensor’s FOM shoots to 5897.082 RIU−1. The comparison reveals that the above FOM values are way better than for the existing FOSPR sensors. For biosensing, MoS2-based FOSPR sensor should be used, as its longer ORD wavelength (1099.35 nm) leads to reduced Rayleigh scattering and lesser photodamage of tissue. For other sensing applications, graphene-based FOSPR sensor at its ORD condition can be used.

The Ag layer thickness effect on the figure of merit of the AZO/Ag bilayer prepared by DC sputtering of AZO and thermal evaporation method of Ag

In this study, first we had prepared four samples of the AZO thin film on the glass substrate with the thickness of ∼200 nm then the Ag layer was deposited with the thickness of 8 nm, 16 nm and 23.3 nm on three of the AZO thin film samples respectively. DC sputtering was used as deposition method of AZO on the glass substrate and deposition method of Ag on the AZO was thermal evaporation. The AZO and the AZO/Ag had been deposited at room temperature afterwards they were annealed at 450 °C. Before and after annealing, x-ray diffraction, AFM, UV-Vis spectroscopy and four-point probe were used. Also before annealing, SEM was used to obtain thickness of samples. The AZO/Ag bilayer with the thickness of 16 nm of the Ag layer indicates maximum transmittance 45% for before and 72% for after annealing. Due to the low sheet resistance of 8.41 Ω/sq, the AZO/Ag bilayer with the thickness of 16 nm shows the figure of merit before annealing.

Characteristics of indium zinc oxide/silver/indium zinc oxide multilayer thin films prepared by magnetron sputtering as flexible transparent film heaters

Indium zinc oxide/silver/indium zinc oxide multilayer structures with a very low resistivity and high transmittance were deposited on a polyethylene terephthalate substrate by DC magnetron sputtering. The electrical, optical, mechanical, and thermal properties of the multilayer films were investigated at different Ag layer thicknesses (10–20 nm). The multilayers demonstrated relatively constant resistance change (∆R/ R0) over repeated bending tests with a radius of 8 mm. Efficient Joule heating could increase the operating temperature of the film heaters (7.3 Ω/□) to 73.7 °C in ~20 s at 3 V; moreover, the heat distribution remained uniform after bending tests. A high transmittance (84.7%) at a wavelength of 550 nm and low sheet resistance (7.3 Ω/□) of the optimized multilayer was obtained at an Ag layer thickness of 15 nm. These results indicate that the multilayers are promising as transparent film heaters for next-generation flexible applications.

Multiple functional coating highly inert fiber surfaces of para-aramid filament yarn

High-performance textile filament yarns such as para-aramid filament yarn (p-AF) will be used as the base material for the development of sensor yarns (SY) because p-AF offer high tensile strengths and moduli of elasticity, as well as high decomposition temperatures and elongation. However, p-AF has an inert or hydrophobic surface, i.e. a lower polar fraction of the total surface energy that does not allow metallization. The aim of this work is the development of a multifunctional sensor yarn consisting of inert and hydrophobic p-AF. By applying new technologies developed at the Institute of Textile Machinery and Textile High Performance Materials Technology, a homogeneous, completely coated first (1st) and second (2nd) silver layer was built on the p-AF filament yarn surface. The first silver layer monitors the damage in the thermoplastic composite globally and the second silver layer locally. Between two silver layers is an insulation layer. Thus, three layers are built on the p-AF surface. The surface morphology has been determined by light and scanning electron microscopy to assess the Ag layer properties such as structure, homogeneity, and cracking. For structural analysis, p-AF were investigated using a Fourier transform infrared spectrometer. The dispersive and polar component of the surface energy of the treated and pretreated p-AF was measured by using a single fiber Tensiometer (Kruess K100. The Ag and insulation layer thickness was determined after coating and metallization. Textile physical tests of the tensile strength, elasticity modulus, elongation at break and filament yarn fineness of the p-AF before and after the silvering were carried out. The length related electrical resistance of the 1st and 2nd silver layer of the p-AF filament yarns was measured by a Multimeter Fluke 45 (Fluka Germany GmbH) with two wire methods.

Direct quantification of mechanical responses of TiSiN/Ag multilayer coatings through uniaxial compression of micropillars

The TiSiN/Ag multilayer coatings with fixed TiSiN layer thickness and different individual Ag layer thicknesses were prepared by arc ion plating. Quantification of mechanical response of TiSiN/Ag multilayer coatings through uniaxial micropillar compression tests was carried out to identify the elastic modulus, fracture strength, deformation and failure mechanism. The deformation and failure behavior of the micropillars assessed by direct scanning electron microscopy observation after the uniaxial compression tests revealed a linear increase of stress with strain up to a fracture point for all 1-μm micropillars, indicating an elastic response with brittle failure. In addition, in-situ micro-compression was carried out mainly on the micropillars with diameters of 600 nm and 300 nm; the stress-strain curves show an initial linear elastic response until the yield point was reached, followed by plastic deformation with a total strain of 27.99% and 42.7%, respectively. Moreover, size effect was also found in the micropillar compressions in which, the 300-nm micropillar showed the highest fracture strength of 16.71 ± 0.63 GPa.

Infrared extinction and microwave absorption properties of hybrid Fe3O4@SiO2@Ag nanospheres synthesized via a facile seed-mediated growth route

Fe3O4@SiO2@Ag ternary hybrid nanoparticles were synthesized via a facile seed-mediated growth route. X-ray diffraction, transmission electron microscopy and vibrating sample magnetometer measurements were used to characterize the as-prepared product. The results indicated that the nanoparticles exhibited excellent magnetic properties and an extremely dense structure with Ag layer thicknesses of 30, 40, and 50 nm. Furthermore, the microwave shielding effectiveness exceeded 20 dB over almost the entire frequency range (2–18 GHz), and the effectiveness obviously improved as the thickness of the Ag layer increased. In addition, the IR extinction coefficient of the nanoparticles was calculated by a finite-difference time-domain method, which showed that the nanoparticles can inherit the extinction performance of pure silver when the Ag shell thickness was 30 nm. Specifically, after assembling into chains, the peak position of the IR extinction curves displayed a significant redshift and an intensity increase as the number of nanoparticles increased in the chain, which dramatically promoted the IR extinction capability. As a result, the Fe3O4@SiO2@Ag nanoparticles are expected to be used as a new multispectral interference material.

Improvement of MoO3/Ag/MoO3 multilayer transparent electrodes for organic solar cells by using UV–ozone treated MoO3 layer

Ultraviolet ozone (UVO) treatment of molybdenum trioxide (MoO3) appears to be a simple and efficient method for obtaining highly continuous and smooth silver (Ag) thin films in the thermally evaporated MoO3/Ag/MoO3 (MAM) multilayered structure as transparent electrodes for small-molecule organic solar cells (OSCs). It is observed that UVO treatment can oxidatively modify the non-stoichiometric MoO3 (or MoO3-x) surfaces, further increasing the Mo6+/Mo5+ composition ratio and work function of MoO3-x. Importantly, the use of UVO treatment for the MoO3 bottom layer effectively improves the wettability of Ag on MoO3 and enhances the lateral growth of Ag thin film, resulting in a reduction of the percolation threshold thickness of the continuous Ag layer. Due to the formation of an ultrathin Ag interlayer with a continuous and smooth surface morphology, the MAM multilayered electrode after UVO treatment of MoO3 for 3 min has excellent optical and electrical properties, including a high maximum transmittance of 89.1% and a low sheet resistance of 8.0 Ω/sq. When the optimal UVO-treated MoO3/Ag (7.5 nm)/MoO3 films are used as the anode in OSCs with the copper phthalocyanine (CuPc)/fullerene (C60) planar heterojunction structure, the OSCs have a power conversion efficiency of 0.55%, which is 2.0 and 1.2 times higher than that of devices with untreated MoO3/Ag (7.5 nm)/MoO3 (0.27%) and MoO3/Ag (10 nm)/MoO3 electrodes (0.46%), respectively, and competitive with that of indium-tin-oxide-based devices. Because of almost full surface coverage of the Ag interlayer, UVO treatment of MoO3 in MAM multilayered electrodes can improve charge carrier injection/extraction at the anode contact and hence improve the photovoltaic performance of OSCs.

Polymer-metal-polymer (PMP) multilayer transparent electrode for organic optoelectronics

Metal embedded polymer hybrid materials have found a niche of applications in energy and display domain. Herein, we report results of investigations on Polystyrene-Silver-Polystyrene (PAP) multilayer structure (<100 nm) exhibiting promising electrical and optical properties useful for the organic transparent electrode. Polystyrene and silver layers were obtained by spin coating and DC sputtering, respectively. Ag layer thickness was varied (4 nm to 30 nm) to optimize optical and electronic properties. Highest average transparency towards visible light was measured ≥70% for 8 nm thick Ag layered PAP structure whereas a minimum value of resistivity 6.03E−5 Ω was obtained for 12 nm thick Ag layer which implies the formation of the uniform continuous layer at this thickness. The study is supplemented with the characterization to prove smooth top layer which is required for growth of secondary layers (FESEM), chemical state of the trilayer (XPS measurement), uniformity in the chemical composition of the trilayer (Depth profiling) and structural properties (X-Ray diffraction and Raman spectroscopy). The importance of the present investigation lies in the synthesis process which is easy, low cost and allows tuning of optoelectronic properties of TCE as required by the application.

Studies of Ag/TiO2 plasmonics structures integrated in side polished optical fiber used as humidity sensor

In this report, we investigate the effects of Ag/TiO2 integrated in side polished optical fiber. Several layers of Ag thickness has been deposited on glass substrates using electron beam (e-beam) evaporation technique in order to determinate the influence of silver with combination of TiO2 on final properties of the sensor. Several thicknesses of Ag NPs were sets to 5 nm, 7 nm, 12 nm, and 16 nm. Another layer of metal oxide, specifically titanium oxide (TiO2) is introduced, covering the Ag layer to study the effect of metal oxides toward the performance of the device. The morphology of the samples was observed using a field-emission scanning electron microscope (FESEM), Raman UV–Vis spectroscopy and Raman photoluminescence (PL) spectroscopy. A CST Microwave used to observe the electric field distribution for all the samples to support the experimental findings. Based on the simulation analysis, two thicknesses of Ag layers (7 nm and 16 nm) were selected to be coated on a side polished optical fiber and tested as a humidity sensor. TiO2 layer was introduced to see the enhancement in the sensing measurements as a suitable material for trapping the photo generated electrons and avoiding charge recombination. From this observation, it can be conclusively shows that the sensitivity of the sensor is improved with integration of Ag NPs and TiO2. Based on the experimental results, the sensor of Ag/TiO2 with 7 nm of Ag layers shows the best characteristics in humidity sensing with good sensitivity and linearity of 0.9201% and 13.4 mW/% RH, respectively.

Fabrication of Highly Packed Plasmonic Nanolens Array Using Polymer Nanoimprinted Nanodots for an Enhanced Fluorescence Substrate.

A simple and cost-effective fabrication method for plasmonic nanolens arrays (PNA) with a narrow gap has been proposed for fabricating enhanced fluorescence substrates, in which the fluorophores interacting with the enhanced electromagnetic field generated by localized surface plasmons provide a higher fluorescence signal. The PNA was fabricated by the sequential depositions of the SiO2 and Ag layers on a UV-nanoimprinted nanodot array with a pitch of 500 nm, a diameter of 250 nm, and a height of 100 nm. During the deposition processes, the shape of the nanodots changed to that of nanolenses, and the gap between the nanolenses was decreased via sidewall deposition. To examine the feasibility of the fabricated PNA for enhanced fluorescence application, a streptavidin-Cy5 (SA-Cy5) conjugate dissolved in a saline buffer solution was spotted on the PNA, and the fluorescence signals of the SA-Cy5 were measured and compared with those on a bare glass substrate. The enhancement factor was affected by the gap between the nanolenses, and the maximum enhancement factor of ~128 was obtained from the PNA with a SiO2 layer thickness of 150 nm and an Ag layer thickness of 100 nm. Finally, an electromagnetic field analysis was used to examine the fluorescence signal enhancement, and was conducted using rigorous coupled wave analysis.

Effect of Ag incorporation on the electrical and optical properties of AZO/Ag/AZO multilayer transparent conducting electrode

Silver (Ag) incorporated aluminium doped zinc oxide (AZO) based multilayer films were fabricated for transparent conducting electrode applications. AZO and Ag thin film layers were deposited using direct current magnetron sputtering system without breaking the vacuum. By carefully optimizing the thickness of the metal layer, the minimum sheet resistance of 6 Ω/square was achieved with 70% of transmission in the visible wavelength region. The surface morphology of the film was studied with atomic force microscope mapping in 5 µm × 5 µm area of the multilayer structure. The significance of the Ag layer thickness in determining the electrical and optical properties of the multilayer film was investigated.

Wear Resistance of Cu/Ag Multilayers: A Microscopic Study.

The microscopic wear behavior of copper-silver multilayer samples was studied by performing sliding wear tests using a tribo-indenter. Multilayers with an average composition of Cu90Ag10 and Ag layer thicknesses ranging from 2 to 20 nm were grown by magnetron sputtering. For reference, a homogeneous Cu90Ag10 solid solution film was similarly grown. The thin films were subjected to two-dimensional wear tests by rastering a cono-spherical diamond indenter under loads of 100-400 μN for 1-20 consecutive passes or cycles. The wear volumes were determined by atomic force microscopy. Characterization of the specimens employed nanoindentation, nanoscratch, and transmission electron microscopy (TEM). Wear rates were found to reach steady state after five cycles or less. The hardness values of the as-grown and worn samples both increased with decreasing thickness of the Cu and Ag layers, whereas the steady-state wear rates decreased. Notably, the wear resistance increased faster than the corresponding increase in indentation hardness, indicating a deviation from the Archard's law. An inverse relationship between the wear rate and hardness was, however, recovered when using scratch hardness, suggesting that scratch hardness is a better predictor of wear resistance. Characterization of subsurface wear microstructures by TEM revealed that forced chemical mixing and dissolution of layers occur to a depth of ≈40 to 50 nm, stabilizing a chemically homogeneous solid solution below the wear surface. Comparative wear tests on thicker multilayers revealed that Cu/Ag interfaces reduced the wear rate significantly, thus helping to rationalize the high wear resistance of thin multilayers.

Inverse MR and Dual-AMR Phenomena in Co/CoO/Ag/Co Sandwiches

Band-form Co/CoO/Ag/Co sandwiches were prepared using radio-frequency magnetron sputtering. The sandwiches had rather thick Co (tCO = 63 nm) and Ag (tAg = 2 ÷ 65 nm) layers and a super-thin paramagnetic cobalt monoxide (CoO) layer (< 1 nm) inserted in the Co/Ag interface. The sandwiches exhibited anomalous magnetoresistance (MR) behavior depending on the tAg value. Inverse magnetoresistance (IMR) effect was observed only at thin tAg values of 2 nm and 6 nm, whereas the dual-anisotropic MR (dual-AMR) occurred at thicker tAg values of 12 nm, 25 nm and 65 nm. A superposition of the dual-AMR and the weak IMR effects was obtained at the thickest Ag layer of 65 nm. The origin of these anomalous MR behaviors was discussed to show the prominent role of the CoO layer and large thickness of the Co and Ag layers.

Efficient non-doped blue phosphorescent organic light-emitting devices by incorporating Ag-island nanostructures

In this work, vacuum-evaporated Ag-island nanostructures were incorporated into the electron transporting layer (ETL) and their effects on the performance of non-doped blue phosphorescent organic light-emitting devices (PhOLEDs) using an ultrathin phosphorescent dye as the emitting layer (EML) were investigated systematically. By changing the thickness and deposition rate of Ag layer, the surface morphologies and resonance absorption spectra of the Ag-island nanostructures can be fine modulated. The device performance is significantly dependent on the structure and position of Ag layer. The experimental results indicate that 0.5 nm Ag layer deposited at a rate of 0.06 Å/s presents excellent spectral overlap between the resonance absorption spectra of Ag-island layer and the emission spectra of EML that impacts the electrical properties. Compared to the reference device without Ag-island layer, the current efficiency of the optimized device was enhanced by 54% from 15.1 cd/A to 23.2 cd/A when 0.5 nm Ag-island layer was incorporated into ETL with 20 nm away from EML. The performance enhancement is attributed to the synergistic effects for the improved electron transport properties induced by the Ag-island layer and the effective couplings between excitons and localized surface plasmons (LSPs).

Effect of silver thickness on structural, optical and morphological properties of nanocrystalline Ag/NiO thin films

Silver (Ag) nanolayers were deposited on nickel oxide (NiO) thin films by DC magnetron sputtering. The thickness of Ag layers was in range of 20–80 nm by variation of deposition time between 10 and 40 s. X-ray diffraction results showed that the crystalline properties of the Ag/NiO films improved by increasing the Ag film thickness. Also, atomic force microscopy and field emission scanning electron microscopy images demonstrated that the surface morphology of the films was highly affected by film thickness. The film thickness and the size of particles change by elevating the Ag deposition times. The composition of films was determined by Rutherford back scattering spectroscopy. The transmission of light was gradually reduced by augmentation of Ag films thickness. Furthermore; the optical band gap of the films was also calculated from the transmittance spectra.

Wafer-Scale Hierarchical Nanopillar Arrays Based on Au Masks and Reactive Ion Etching for Effective 3D SERS Substrate.

Two-dimensional (2D) periodic micro/nanostructured arrays as SERS substrates have attracted intense attention due to their excellent uniformity and good stability. In this work, periodic hierarchical SiO2 nanopillar arrays decorated with Ag nanoparticles (NPs) with clean surface were prepared on a wafer-scale using monolayer Au NP arrays as masks, followed by reactive ion etching (RIE), depositing Ag layer and annealing. For the prepared SiO2 nanopillar arrays decorated with Ag NPs, the size of Ag NPs was tuned from ca. 24 to 126 nanometers by controlling the deposition thickness of Ag film. Importantly, the SiO2 nanopillar arrays decorated with Ag NPs could be used as highly sensitive SERS substrate for the detection of 4-aminothiophenol (4-ATP) and rhodamine 6G (R6G) due to the high loading of Ag NPs and a very uniform morphology. With a deposition thickness of Ag layer of 30 nm, the SiO2 nanopillar arrays decorated with Ag NPs exhibited the best sensitive SERS activity. The excellent SERS performance of this substrate is mainly attributed to high-density “hotspots” derived from nanogaps between Ag NPs. Furthermore, this strategy might be extended to synthesize other nanostructured arrays with a large area, which are difficult to be prepared only via conventional wet-chemical or physical methods.

Tailored plasmon-induced transparency in attenuated total reflection response in a metal\u2013insulator\u2013metal structure

We demonstrated tailored plasmon-induced transparency (PIT) in a metal (Au)–insulator (SiO2)–metal (Ag) (MIM) structure, where the Fano interference between the MIM waveguide mode and the surface plasmon polariton (SPP) resonance mode induced a transparency window in an otherwise opaque wavenumber (k) region. A series of structures with different thicknesses of the Ag layer were prepared and the attenuated total reflection (ATR) response was examined. The height and width of the transparency window, as well as the relevant k-domain dispersion, were controlled by adjusting the Ag layer thickness. To confirm the dependency of PIT on Ag layer thickness, we performed numerical calculations to determine the electric field amplitude inside the layers. The steep k-domain dispersion in the transparency window is capable of creating a lateral beam shift known as the Goos–Hänchen shift, for optical device and sensor applications. We also discuss the Fano interference profiles in a ω − k two-dimensional domain on the basis of Akaike information criteria.

Features of electronic and lattice mechanisms of transboundary heat transfer in multilayer nanolaminate TiAlN/Ag coatings

Plasmon resonance heterogeneities were identified and studied along Ag and TiAlN layers within a multilayer stack in nanolaminate TiAlN/Ag coatings. For this purpose, a high-resolution plasmon microscopy was used. The plasmons intensity, energy, and depth of interface plasmon-polariton penetration were studied by scanning reflected electron energy loss spectroscopy. The heat conductivity of such metal-insulator-metal (MIM) nanolaminate coatings was measured by laser reflectometry. Dependencies of thermal conductivity coefficient of coatings, MIM interfaces, and resistivity of Ag layers as a function of the Ag-TiAlN bilayer thickness were calculated on the basis of experimental data. The contribution of plasmon resonance confinement to the abnormal lower thermal conductivity in the MIM metamaterial with Ag layer thickness below 25 nm is discussed. In particular, the results highlight the relevant role of different heat transfer mechanisms between MI and IM interfaces: asymmetry of plasmon-polariton interactions on upper and lower boundaries of Ag layer and asymmetry of LA and TA phonons propagation through interfaces.

Semi‐transparent plastic solar cell based on oxide‐metal‐oxide multilayer electrodes

AbstractSemi‐transparent plastic solar cells are currently highly attractive for their potential as the most prominent components for building‐integrated photovoltaics. However, the power conversion efficiency (PCE) of semi‐transparent plastic solar cells still lags behind due to the lack of a suitable transparent top electrode which can be easily fabricated. Here, we demonstrate high performance semi‐transparent plastic solar cells by introducing an oxide‐metal‐oxide (OMO) multilayer composed of MoO3 and Ag as a transparent top electrode. Because the conductivity of the OMO electrode is governed by an intermediate Ag layer sandwiched between 2 MoO3 layers, the PCE also strongly depends on the thickness of the intermediate Ag layer in the OMO electrode. By controlling the thickness of Ag layer, we obtained various PCE values from 4.5% with ~50% maximum transparency in the visible region to 9.1% with ~5% maximum transparency in the visible region. In addition, in order to get closer to practical application, 2 sizes of mini‐module devices were fabricated on a larger (10.0 cm × 10.0 cm) substrate for outdoor operation and small‐sized (7.0 cm × 5.0 cm) substrates for indoor operation were demonstrated using 3 materials of different color.

Highly transparent and conducting ITO/Ag/ITO multilayer thin films on FEP substrates for flexible electronics applications

Transparent and conducting ITO/Ag/ITO (IAI) multilayer coatings were deposited on glass and flexible fluorinated ethylene propylene (FEP) substrates by reactive sputtering using metallic In:Sn (90%:10%) and Ag targets at room temperature. Middle Ag layer thickness was optimized to obtain maximum figure of merit (ϕ) and the optimum Ag layer thickness was found to be ~13nm. The optimized IAI multilayer on glass substrate showed transmittance of ~88.6% and sheet resistance of ~7.1Ω/sq. The transmittance increased to ~91.4% for the IAI multilayer deposited on one side etched glass. The optimized IAI multilayer coating was also deposited on flexible FEP substrates. The electrical, optical, structural and morphological properties of IAI deposited on glass and FEP substrates were compared. IAI deposited on FEP substrate showed transmittance of ~90.2% at λ = 550nm, sheet resistance of ~6.9Ω/sq. and figure of merit of ~52 × 10−3Ω−1. Bending test of IAI deposited FEP proved the high flexibility of IAI multilayer for the flexible transparent electrode applications. Solar selectivity study of IAI on FEP substrate showed it can effectively reflect the higher wavelength region of solar spectrum and can be used as a flexible solar spectrum segregator. Optical haze measurements of IAI coated glass and FEP show that high haze value can be achieved by increasing the roughness on non-coated side of the FEP substrate.