Sputtering Of Silver Research Articles

Silver sputtering into a liquid matrix containing mercaptans: the systematic size control of silver nanoparticles in single nanometer-orders

A novel methodology to synthesize silver nanoparticles with precisely controlled diameters in single nano-meter orders by sputtering into a liquid matrix containing mercaptans as an environmental friendly preparation without reductants.

Highly transparent ZTO/Ag/ZTO multilayer electrode deposited by inline sputtering process for organic photovoltaic cells

Indium-free ZTO/Ag/ZTO multilayer electrodes were deposited on glass by RF sputtering of zinc tin oxide (ZTO) and pulsed DC sputtering of silver (Ag) at room temperature in the specially designed Inline sputtering system and evaluated as transparent electrode of organic photovoltaic cells (OPVs). The dependence of the electrical and optical properties of ZTO films on the O2/Ar + O2 ratio was investigated. We fabricated the ZTO/Ag/ZTO multilayer electrode with a sheet resistance of 8.38–10.18 Ω sq−1 and average transmittance of 84.4–85.5% in the visible region (λ = 380–770 nm), which is compatible with commercial indium tin oxide (ITO). As an application, organic solar cells fabricated on the ZTO/Ag/ZTO multilayer electrodes with the conventional device architecture were compared with those on commercial ITO electrodes. The bulk heterojunction OPVs fabricated on the multilayer electrodes exhibited a short-circuit current (JSC) of 7.06 mA cm−2, a fill factor (FF) of 0.62, an open-circuit voltage of (VOC) of 0.64 V, and a power-conversion efficiency of 2.80%. This indicates that ZTO/Ag/ZTO multilayer electrode is a promising electrode scheme for bulk heterojunction organic photovoltaic cells (BHJ-OPVs).

Amperometric detection of hydrogen peroxide using a nanofibrous membrane sputtered with silver

In this study, a novel hydrogen peroxide (H2O2) electrochemical sensor was fabricated by covering a nanofibrous membrane on a glassy carbon electrode (GCE). Silver (Ag) nanoparticles were deposited on the two surfaces (front and back) of the nanofibrous membrane by a sputtering-deposition process with a high purity silver sputtering target. Cyclic voltammetric measurements revealed that the obtained nanofibrous membrane exhibited a well-defined pair of redox peaks and a prominent electrocatalytic activity toward H2O2. Amperometric measurements indicated that the sensor based on the silver coated nanofibrous membrane showed a linear response to H2O2 concentrations ranging from 10 μM to 16.5 mM with a detection limit of 4 μM and a maximum sensitivity of 157 mA cm−2 M−1. In addition, the sensor also exhibited good selectivity and stability, and can offer a novel method to detect H2O2.

Mass Spectrometric Characterizations of Ions Generated in RF Magnetron Discharges during Sputtering of Silver in Ne, Ar, Kr an.d Xe Gases

The article reports mass spectrometric characterizations of ions generated in RF magnetron discharges generated using silver targets and Ne, Ar, Kr and Xe gases. Both the amount of ions and ion energies in magnetron discharges were investigated. The following ions X+, Ag+, (XAg)+, X2+, Ag2+, X++ and Ag++ were found in the RF discharges; here X = Ne, Ar, Kr, Xe is the inert gas atom and Ag is the silver atom. The amount of individual ions, their energies and ion energy distribution (IED) functions as a function of sputtering gas pressure were measured. It is shown that the sputtering gas pressure strongly influences the generation of ions, their amount and energy in the RF magnetron discharges. The knowledge of the energies and amounts of individual ions is of a key importance in the deposition of thin films with controlled properties using RF magnetron discharges.

Silver-Assisted Laser Desorption Ionization For High Spatial Resolution Imaging Mass Spectrometry of Olefins from Thin Tissue Sections

Silver has been demonstrated to be a powerful cationization agent in mass spectrometry (MS) for various olefinic species such as cholesterol and fatty acids. This work explores the utility of metallic silver sputtering on tissue sections for high resolution imaging mass spectrometry (IMS) of olefins by laser desorption ionization (LDI). For this purpose, sputtered silver coating thickness was optimized on an assorted selection of mouse and rat tissues including brain, kidney, liver, and testis. For mouse brain tissue section, the thickness was adjusted to 23 ± 2 nm of silver to prevent ion suppression effects associated with a higher cholesterol and lipid content. On all other tissues, a thickness of at 16 ± 2 nm provided the best desorption/ionization efficiency. Characterization of the species by MS/MS showed a wide variety of olefinic compounds allowing the IMS of different lipid classes including cholesterol, arachidonic acid, docosahexaenoic acid, and triacylglyceride 52:3. A range of spatial resolutions for IMS were investigated from 150 μm down to the high resolution cellular range at 5 μm. The applicability of direct on-tissue silver sputtering to LDI-IMS of cholesterol and other olefinic compounds presents a novel approach to improve the amount of information that can be obtained from tissue sections. This IMS strategy is thus of interest for providing new biological insights on the role of cholesterol and other olefins in physiological pathways or disease.

RF magnetron sputtering of silver thin film in Ne, Ar and Kr discharges—plasma characterisation and surface morphology

We have carried out a systematic study of the influence of Ne, Ar and Kr working gases on both plasma and film properties of RF magnetron sputtering of silver. The magnetron plasma was characterised by optical emission spectroscopy (OES) and mass spectrometry. Silver thin film morphology was examined by SEM and AFM. We studied influence of magnetron power and working gas pressure on the plasma composition. The magnetron power was varied from 25 to 100W. The ambient pressure was changed from 0.5Pa to 3Pa. Both mass and OES spectra revealed presence of highly excited plasma in the substrate vicinity for all sputtering gases. The increasing OES signal intensities of Ag and Ag+ with increasing RF power and gas pressure were observed. However, in Ar discharge there was no Ag+ signal detected by OES at lower pressures of 0.5Pa and 1Pa. Similar profiles of the energy distributions of the ions with a maximum located around 19eV were obtained in Ar and Kr discharges at pressure of 3Pa while a maximum at 28eV was measured in Ne discharge. Ag2+ and AgX+ radicals, where X is atom of particular inert-working gas, were observed in the mass spectra. Silver thin film deposited in Ne gas revealed lower roughness than the films deposited in the other gases.

Advantages of highly ionized pulse plasma magnetron sputtering (HIPIMS) of silver for improved E. coli inactivation

This study addresses the DC-magnetron sputtering (DCMS) of Ag-films on polyester and compares the results found for the E. coli inactivation with the inactivation obtained when applying highly ionized pulse plasma power magnetron sputtering (HIPIMS). The amounts of Ag needed to inactivate E. coli by HIPIMS sputtering were an order of magnitude lower than with DCMS indicating a significant saving of noble metal and concomitantly a faster E. coli inactivation was observed compared to samples sputtered with DCMS. Higher current densities applied with DCMS led to shorter E. coli inactivation times and this trend was observed also for HIPIMS sputtered samples. By DCMS the thicker layers needed to inactivate E. coli comprised slightly larger Ag-aggregates compared to the thinner Ag-layers sputtered by HIPIMS to inactivate E. coli within short times. Longer sputtering times by DCMS and HIPIMS lead to optically darker Ag-deposits reaching the absorption edge of silver absorption of ~1000nm. Mass spectroscopic analyses indicated that HIPIMS produced a much higher amount of Ag1+ and Ag2+ compared to DCMS due to the higher peak discharge current employed in the former case.

Plasma‐Mediated Nanosilver‐Organosilicon Composite Films Deposited on Stainless Steel: Synthesis, Surface Characterization, and Evaluation of Anti‐Adhesive and Anti‐Microbial Properties on the Model Yeast Saccharomyces cerevisiae

AbstractA series of plasma‐mediated thin films (≈175 nm), containing silver nanoparticles embedded in an organosilicon matrix with controllable properties (silver content, nanoparticle size, matrix composition), were deposited onto stainless steel and chemically and structurally characterized, using a large set of analytical techniques. The process originality relies on a dual strategy, associating silver sputtering, and simultaneous plasma enhanced chemical vapor deposition, in an argon‐hexamethyldisiloxane plasma, using an asymmetrical radiofrequency discharge at 13.56 MHz. X‐ray photoelectron spectroscopy, FTIR spectroscopy, and Raman spectroscopy demonstrated the inclusion of metallic silver nanoparticles within the organosilicon‐like matrix. Silver content was directly related to the plasma process conditions. TOF‐SIMS analysis revealed that the film composition was homogeneous in depth. SEM and TEM observations confirmed the nanoparticle‐based morphology of the coatings, dependent on the silver content. The film anti‐adhesive potentialities were evaluated in vitro toward the model yeast Saccharomyces cerevisiae by performing shear‐flow induced detachment experiments, under well‐controlled hydrodynamic, and physico‐chemical conditions. The maximal effect was achieved for the organosilicon matrix alone. When silver nanoparticles were incorporated, yeast detachment was lower, probably due to the strong affinity of embedded silver for biological components of the cell wall surface. The presence of methyl groups in the matrix network could also promote enhanced hydrophobic yeast/coating interactions. An anti‐microbial action of silver (conjugated effect of nanoparticles and chemisorbed Ag+ ions and complexes released through nanoparticle oxidation) at the immediate vicinity of the coating surface occurred, depending on the silver content. In the conditions under study, a maximal 1.9 log reduction in viable counts was observed, compared to control conditions with bare stainless steel. Based on NanoSIMS50 elemental mapping, various characteristic cell sub‐structures and inclusions were detected, such as cell wall and nucleus. After yeast exposure to nanosilver‐containing films, a quite homogeneous distribution of released silver all over the cell was observed, overlapping with sulfur and phosphorous signals.magnified image

Performance of viscose rayon based activated carbon fabric modified by sputtering silver and continuous plasma treatment

In this study, the preparation of viscose rayon based activated carbon fabric (ACF) absorbents with antibacterial ability and modifications introduced by silver sputtering has been investigated. Viscose rayon based knitted fabric, pre-treated by a composite flame retardant, was used as the precursor. The fabric then underwent oxidation, carbonization and activation processes in a semi-open high-temperature erect furnace with a steam activator to produce ACF absorbents. Experimental results have shown that the ACF absorbents produced by the action of mixing steam and air had the largest BET specific surface area at about 1713 m2/g and the absorption amount of carbon tetrachloride was about 100.5%. However, the BET specific surface area of ACF-Ag adsorbents decreased because pores were destroyed by etching and deposition of silver particles. The ACF-Ag adsorbent, however, showed effective antibacterial and sterilizing properties. When the ACF-Ag adsorbent was placed in deionized water, a large amount of Ag ions eluted within the first 48 h. The elution gradually decreased after 96 h with about 0.2855 ppm of Ag ions eluting after seven days.

Transparent Rectifying Contacts for Visible-Blind Ultraviolet Photodiodes Based on ZnO

The authors report on the fabrication of transparent rectifying contacts by reactive sputtering of silver or platinum on heteroepitaxially grown zinc oxide. The contacts exhibit Schottky-like current–voltage behavior; the effective barrier height is $$0.73\,\hbox{eV}$$ for both materials. In photovoltaic mode, the transparent rectifying contacts reach external quantum efficiencies as high as 32% and responsivities as high as $$0.1\,\hbox{A/W}$$ .

The investigation of oxidized silver nanoparticles prepared by thermal evaporation and radio-frequency sputtering of metallic silver under oxygen

The investigation of oxidized silver nanoparticles by the photoemission (XPS, UPS) and HRTEM methods was performed. The nanoparticles of oxidized silver were obtained in the vacuum chamber by two methods of synthesis: thermal evaporation of silver nanoparticles followed by transferring in convective gas flow and sputtering of oxidized clusters under the action of plasma. Both methods indicated that oxygen interaction with silver nanoparticles depends strongly on its size. It was shown that the chemical bonding of oxygen species stabilized on small particles differs from the oxygen species adsorbed on bulk silver surfaces (monocrystals, foils and large particles). The low charged oxygen with molecular type of bonding stabilizes on particles of size approximately 5nm and smaller. Increasing particle size leads to the dissociation of molecular oxygen species and the formation of strongly charged oxygen composed of oxide nanoparticles like Ag2O or AgO type. The presence of extended defects in the microdomain large nanoparticles facilitates the formation of Ag2O or AgO layers covering metallic nanosilver.

Ageing of plasma-mediated coatings with embedded silver nanoparticles on stainless steel: An XPS and ToF-SIMS investigation

Nanocomposite thin films (∼170 nm), composed of silver nanoparticles enclosed in an organosilicon matrix, were deposited onto stainless steel, with the aim of preventing biofilm formation. The film deposition was carried out under cold plasma conditions, combining radiofrequency (RF) glow discharge fed with argon and hexamethyldisiloxane and simultaneous silver sputtering. XPS and ToF-SIMS were used to characterize Ag-organosilicon films in native form and after ageing in saline solution (NaCl 0.15 M), in order to further correlate their lifetime with their anti-fouling properties. Two coatings with significantly different silver contents (7.5% and 20.3%) were tested. Surface analysis confirmed the presence of metallic silver in the pristine coating and revealed significant modifications after immersion in the saline solution. Two different ageing mechanisms were observed, depending on the initial silver concentration in the film. For the sample exhibiting the low silver content (7.5%), the metal amount decreased at the surface in contact with the solution, due to the release of silver from the coating. As a result, after a 2-day exposure, silver nanoparticles located at the extreme surface were entirely released, whereas silver is still present in the inner part of the film. The coating thickness was not modified during ageing. In contrast, for the high silver content film (20.3%), the thickness decreased with immersion time, due to significant silver release and matrix erosion, assigned to a percolation-like effect. However, after 18 days of immersion, the delamination process stopped and a thin strongly bounded layer remained on the stainless steel surface.

Synchrotron FTIR microspectroscopy of the yeast Saccharomyces cerevisiae after exposure to plasma-deposited nanosilver-containing coating

The present work was focused on elucidating changes in the model yeast Saccharomyces cerevisiae (cell composition, ultrastructure) after exposure to antimicrobial plasma-mediated nanocomposite films. In order to achieve this, a nanosilver-containing coating was deposited onto stainless steel using radiofrequency HMDSO plasma deposition, combined with simultaneous silver sputtering. X-ray photoelectron spectroscopy (XPS) confirmed the presence of silver nanoparticles embedded in an organosilicon matrix. In addition, scanning electron microscopy (SEM) demonstrated the nanoparticle-based morphology of the deposited layer. The antifungal properties towards S. cerevisiae were established, since a 1.4 log reduction in viable counts was observed after a 24-h adhesion compared to control conditions with the matrix alone. Differences in cell composition after exposure to the nanosilver was assessed for the protein region using, for the first time, synchrotron Fourier-transform infrared (FTIR) microspectroscopy of single S. cerevisiae cells, through in situ mapping with sub-cellular spatial resolution. IR spectrum of yeast cells recovered after a 24-h adhesion to the nanosilver-containing coating revealed a significant downshift (20 cm(-1)) of the amide I peak at 1655 cm(-1), compared to freshly harvested cells. This lower band position, corresponding to a loss in alpha-helix structures, is indicative of the disordered secondary structures of proteins, due to the transition between active and inactive conformations under nanosilver-induced stress conditions. No significant effect on the nucleic acid region was detected. The inhibitory action of silver was targeted against both cell wall and intracellular proteins such as enzymes. Transmission electron microscopy (TEM) observations of the yeast ultrastructure confirmed serious morphological and structural damages. A homogeneous protein-binding distribution of nanosilver all over the cell was assumed, since the presence of electron-dense silver clusters was detected not only on the cell surface but also within the cell. For control experiments with the organosilicon matrix alone, no antimicrobial effect was observed, which was consistent with synchrotron FTIR results and TEM observations.

In situ optical spectroscopy during deposition of Ag:Si 3N 4 nanocomposite films by magnetron sputtering

In situ and real time surface differential reflectance (SDR) spectroscopy is employed to study the growth of metallic Ag and/or dielectric Si 3N 4 films during deposition by magnetron sputtering. The measurements during Si 3N 4 sputtering allow determining both the refractive index and the deposition rate. During Ag sputtering, the SDR presents a maximum in the visible range, typical of a surface plasmon resonance (SPR) indicating the 3D growth of silver nanoclusters. After a certain deposition thickness, the SDR change corresponds to a continuous layer growth and allows determining the Ag deposition rate. During Ag/Si 3N 4 alternate deposition, the SDR spectroscopy enables to follow the SPR modifications (position, amplitude and width) not only during the formation of the Ag nanoclusters but also during their capping by a Si 3N 4 matrix and during intermediate steps (holding time after the silver sputtering, Si 3N 4 target ignition and pre-sputtering before the Si 3N 4 deposition) where significant changes are detected. It suggests possible nanocluster reshaping or physicochemical processes occurring at the nanocluster interface during the different steps.

Structure Control in Reactively Sputtered Ag/Cu/(Mn)/O Films

AbstractCopper‐ and silver‐based oxides were deposited on glass and silicon substrates by reactive sputtering in various Ar/O2 mixtures. The deposition conditions range for paramelaconite synthesis is discussed. The structure of silver oxide films is discussed as a function of the oxygen flow rate introduced into the deposition chamber. Ag/Cu/O films were deposited using either co‐sputtering of silver and copper targets or sputtering of composite targets (Ag50Cu50 and Ag60Cu40). The control of the oxygen and/or the silver content allows the formation of various kinds of structures: X‐ray amorphous, metal/oxide nanocomposites or silver/copper oxides. Finally, the effect of copper and/or manganese addition in silver‐based oxides on their thermal stability is presented.magnified image

Plasma deposition of organosilicon polymer thin films with embedded nanosilver for prevention of microbial adhesion

Composite thin films (∼170 nm) containing silver nanoclusters embedded in an organosilicon matrix were deposited by PE-CVD onto stainless steel in order to prevent microbial adhesion. The process originality relies on a dual strategy combining silver sputtering and simultaneous plasma polymerization in argon–hexamethyldisiloxane (HMDSO) plasma, using an asymmetrical RF glow discharge. The metal content in the film was controlled by varying the HMDSO flow rate. Investigation of the physico-chemical properties of the obtained films was conducted by X-ray photoelectron spectroscopy and transmission FTIR spectroscopy. Plasma-mediated coatings were composed of C, O, Si and Ag which was predominantly under metallic form, as indicated by XPS analysis. The presence of Si–H, Si–O–Si, Si–(CH) n –Si and C–H groups was established by FTIR. The yeast Saccharomyces cerevisiae was selected as the model for eukaryotic microorganisms. The maximal anti-adhesive efficiency was achieved for the organosilicon matrix alone. When nanosilver was incorporated into the organic matrix, the efficiency was reduced, especially for high metal contents. Silver antimicrobial property was assumed to be related to Ag + progressive release from the embedded nanoparticles into the surrounding medium. This release was confirmed by ICP-MS measurements. Moreover, silver-containing film antifungal activity was observed towards sessile cells.

Comparative Studies of Silver Nanocomposite Fibers

Functional silver-polypropylene nanocomposite fibers are prepared using melt-compounding and sputter coating techniques. The functional nanostructures formed on the fiber surfaces are characterized by Atomic force microscopy. The Environmental Scanning Electron Microscopy equipped with an energy dispersive X-ray analysis system is employed to examine the chemical compositions of the nanocomposite fibers. It is found that incorporating the silver nanoparticles by melt-compounding caused severe aggregation of the nanoparticles at the polypropylene fiber surface. By contrast, the coverage of the sputter coated fiber surfaces is much more consistent. The anti-bacterial properties of the nanocomposite fibers are also investigated and compared. The antibacterial tests revealed the better performance of silver sputter coated fibers.

Micro-electroforming metallic bipolar electrodes for mini-DMFC stacks

This paper describes the development of metallic bipolar plate fabrication using micro-electroforming process for mini-DMFC (direct methanol fuel cell) stacks. Ultraviolet (UV) lithography was used to define micro-fluidic channels using a photomask and exposure process. Micro-fluidic channels mold with 300 μm thick and 500 μm wide were firstly fabricated in a negative photoresist onto a stainless steel plate. Copper micro-electroforming was used to replicate the micro-fluidic channels mold. Following by sputtering silver (Ag) with 1.2 μm thick, the metallic bipolar plates were completed. The silver layer is used for corrosive resistance. The completed mini-DMFC stack is a 3.5 × 3.5 cm2 fuel cell stack including a 1.5 × 1.5 cm2 MEA (membrane electrode assembly). Several MEAs were assembly into mini-DMFC stacks using the completed metallic bipolar plates. All test results showed the metallic bipolar plates suitable for mini-DMFC stacks. The maximum output power density is 9.3 mW/cm2 and current density is 100 mA/cm2 when using 8 vol.% methanol as fuel and operated at temperature 30°C. The output power result is similar to other reports by using conventional graphite bipolar plates. However, conventional graphite bipolar plates have certain difficulty to be machined to such micro-fluidic channels. The proposed micro-electroforming metallic bipolar plates are feasible to miniaturize DMFC stacks for further portable 3C applications.

Plasma Deposition of Silver Nanoparticles onto Stainless Steel for the Prevention of Fungal Biofilms: A Case Study on Saccharomyces cerevisiae

AbstractA silver nanoparticle composite film was deposited onto stainless steel to reduce the adhesion strength of the model yeast S. cerevisiae. Deposition was carried out under cold‐plasma conditions, combining RF glow discharge and silver sputtering. Shear‐flow‐induced detachment experiments demonstrated the film's anti‐adhesive properties. However, the surface tended to undergo some chemical changes after use, such an increase in hydrophilicity. XPS analysis confirmed the presence of metallic silver for the native plasma‐modified surface and revealed silver oxidation after use. The silver content was also lowered, due to the progressive release of ionic silver from the composite into the medium.magnified image

Surface Plasmon-Polariton Assisted Metal-Dielectric Multilayers as Passband Filters for Ultraviolet Range

We designed and fabricated metal{dielectric multilayers intended for passband fllters in the ultraviolet range. We determined the dispersion characteristics by the Bloch approach to evanescent wave resonant coupling and calculated the spectral characteristics using the transfer matrix method while taking into account real dispersion and absorptive losses. We considered the in∞uence of nanoscale interface roughness as a means to couple evanescent electromagnetic fleld to the propagating far fleld modes. In our structures both propagating and evanescent modes contribute to the overall performance, resulting in an enhanced transmission in the desired range, while retaining a strong suppression of undesired frequencies of more than four orders of magnitude. In our experiments we used radiofrequent sputtering of silver and silica and characterized our multilayers by UV-vis spectroscopy.