New Method For Deposition Research Articles

Study on Ultrathin Silver Film Transparent Electrodes Based on Aluminum Seed Layers with Different Structures.

Ag has the lowest electrical resistivity among all metals, and at the same time, the best optical properties in the visible and near-IR spectral range; it is therefore the most widely employed material for thin-metal-film-based transparent conductors. In this work, an ultra-thin transparent silver film electrode with aluminum as seed layer was prepared by a resistive thermal evaporation technique. Using a range of electrical, optical and surface morphology techniques, it can be noted that the presence of the thin layer of aluminum changes the growth kinetics (nucleation and evolution) of the thermal evaporation of Ag, leading to silver films with smooth surface morphology and high electrical conductivity, and the threshold thickness of the silver film is reduced. It is inferred that the aluminum layer showed a good infiltration effect on the ultra-thin silver film, by analyzing the transmittance spectrum, sheet resistance and surface morphology. Moreover, the average transmittance of silver film with 10 nm is 40% in the 400–2500 nm band, whereas the sheet resistance is 13 Ωsq −1. A series of experiments show that the introduction of Al seed layer has certain effect on improving the properties of transparent conductive silver films. Then, a new method for deposition of 1 nm Al seed layer was proposed; that is, the 1 nm aluminum infiltrated layer is divided into two or more layers, and the average transmittance of silver film with 5 nm is 60% in the 400–2500 nm band, whereas the sheet resistance does not exceed 100 Ω sq−1.

Hybrid perovskite films deposited by thermal evaporation from a single source

Hybrid perovskites, such as MAPbI3, are very promising materials to fabricate highly efficient and low-cost solar cells and photodetectors. In this work, we propose a new method of deposition of hybrid perovskite thin films through thermal evaporation of MAPbI3 powder from a single source for which was evaluated the effect of evaporation parameters (distance, time, substrate temperature, chamber pressure, and crucible heating rate) on the structural, optical, and morphological properties. It was found that it is necessary to control adequately the chamber partial pressure, substrate temperature, and the crucible heating rate in order to obtain single-phase MAPbI3 perovskite films. Also, it was studied the solvent annealing treatment as a method to increase the grain size of evaporated films. Finally, a study of transient and steady-state photoconductivity allowed verifying that the evaporated MAPbI3 films present fast band to band photogeneration and bimolecular recombination, and also that the grain size growth leads to an increase of the photoconductivity intensity due to the improvement of the diffusion length.

Electrophoretic as New Method for Deposition of Polyaniline Derivatives Nanostructure Coatings

In this research, at the commencement, polyaniline (PANi), polyorthoanisidine (PoAnis), polyorthotoluidine (PoTol), and polyorthoamino phenol (PoAP) were synthesized through a chemical polymerization process. Subsequently, the nanostructured coatings of these polymers were electrodeposited on a stainless steel 304 substrate through an electrophoresis method in a solution containing emeraldine salt in multiple solvents (as a colloidal suspension) and aluminum nitrate (as a charging agent). The scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) were employed to assess the structure and determine the synthesized polymer morphology. The SEM images clearly indicated that the particle sizes of all the polymers were less than 100 nm. In electrophoresis approach, voltage, time and the type of solvent are the effective factors and components on the film quality. Henceforward, we commenced studying how these factors can affect the coating of nanostructured polyaniline and its derivatives. The optimum voltage, process time, and solvent amount required for the formation of each nanostructured polymeric coating were obtained as 25 V, 12 min, and ethanol for PANi, 5 V and 8–10 min for PoAP, 30 V and 25 min for PoTol, 37 V and 20 min for PoAnis, respectively.

Discharge with a self-heated hollow cathode and a vaporizable anode in an inhomogeneous magnetic field

This work is devoted to studying the conditions of the stable burning of discharge with self-heated hollow cathode and anode placed in an inhomogeneous magnetic field. Such a discharge generates dense plasma in Ar-O2 mixture, and compression of the discharge column by magnetic field allows efficient evaporation of the anode material. A new method of deposition of oxide coatings through reactive anode evaporation was implemented in such a system. The rate of this process, unlike the reactive magnetron sputtering, is not limited by the low-rate sputtering of oxidized target. In addition, this method provides intense ion bombardment of a coating surface. The terms of suppression of ion-sound oscillations have been determined, and a stable burning of discharge with current up to 40 A at a pressure of Ar-O2 mixtures 0.1 Pa has been achieved. The results of the probe diagnostic of discharge plasma parameters are presented. Nanocrystalline Al2O3 coatings have been deposited in the studied system on the area of 300-600 cm2 with rate 2-5 μm/h at temperatures of 400-600°C.

Deposition of Sorption and Photocatalytic Material on Nanofibers and Fabric by Controlled Sublimation

This paper presents a new method of deposition of photocatalytic sorbent on nanofibers. This deposition uses controlled sublimation of water molecules from the vacuum-gel that is patent-protected. Silica gel nanostructures are precipitated by heterogeneous nucleation on the surface of nanofibres from an aqueous suspension of silicate nanoparticles and semiconductor carbon nitride (C3N4) or graphene nanosheets. After rapid solidification of gel (at least 104K/s), the nanofibers coated with the silica gel dispersion C3N4, or graphene are subjected to controlled sublimation at – 41 °C. This technology produced a nanofibrous material, which is stably coated with a highly porous silicate sorbent including dispersed photocatalytic nanoparticles. This textile material has a total sorption surface area of the order of hundreds m2/g. Unlike conventional sorbents, it is capable due to dispersed photocatalytic nanoparticles to regenerate sorption capacity by the absorption of visible light. The results of the preliminary research confirmed the high application potential of new controlled sublimation technology in the production of regenerable photocatalytic sorption fabrics.

Synthesis of Diamonds from the Microwave Plasma with the Use of Supersonic Gas Flows

A new method of deposition of diamond films with the use of supersonic gas flows activated by a microwave discharge is implemented for the first time. The operation principle of the proposed gas-discharge system is similar to that of a microwave electrothermal thruster. A mixture of hydrocarbons and hydrogen is used as a plasma-forming gas. It is demonstrated that the proposed method allows the plasma-forming gas to be used at pressures far above the upper limit of the pressure range of modern microwave plasma systems for chemical vapor deposition of diamond films (approximately 40 000 Pa).

The reactor-activator for gas-jet deposition of diamond structures.

This paper presents a new method of deposition of diamond and diamond like structures by using the original reactor for activation of carbonaceous gas mixtures. One of the important characteristics of the described reactor is the power efficiency owing to low heat losses. The new method of gas flow formation opens new possibilities to get important trade-offs (wide range of background conditions and others). The principal possibility of diamond deposition is proved by experiments with the flow of hydrogen and methane mixture in tungsten resistively heating cylindrical channels. Electron microphotographs and Raman spectrum of deposited structures prove the fact that deposited samples are diamond structures. Numerical study of the mixture flow through the reactor was carried for optimization of gas flow conducted to a substrate.

In vitro evaluation of bioactivity of chemically deposited hydroxyapatite on polyether ether ketone.

Polyether ether ketone (PEEK) is considered the best alternative material for titanium for spinal fusion cage implants due to its low elasticity modulus and radiolucent property. The main problem of PEEK is its bioinert properties. Coating with hydroxyapatite (HA) showed very good improvement in bioactivity of the PEEK implants. However the existing methods for deposition of HA have some disadvantages and damage the PEEK substrate. In our previous study a new method for deposition of HA on PEEK was presented. In this study cell proliferation of mesenchymal stem cell and apatite formation in simulated body fluid (SBF) tests were conducted to probe the effect of this new method in improvement of the bioactivity of PEEK. The mesenchymal stem cell proliferation result showed better cells proliferation on the treated layer in comparison with untreated PEEK. The apatite formation results showed the growth of the HA on the treated PEEK but there was not any sight of the growth of HA on the untreated PEEK even after 2 weeks. The results showed the new method of the HA deposition improved the bioactivity of the treated PEEK in comparison with the bare PEEK.

Selective deposition of Pt onto supported metal clusters for fuel cell electrocatalysts

We report a new method for deposition of Pt on a metal core to develop real electrocatalysts with significantly reduced amounts of expensive Pt as well as enhanced activity for oxygen reduction reaction. Ru and Pd have different crystal structures and modify the electronic structure of Pt to a different extent (shifts in d-band center). They were chosen as core materials to examine whether hydroquinone dissolved in ethanol can be used to deposit additional Pt atoms onto preformed core nanoparticles, and whether the modified d-character of Pt on different host metals can result in the enhanced ORR activity. The physicochemical characteristics of Pd-Pt and Ru-Pt core-shell nanoparticles are investigated. The core-shell structure was identified through a combination of experimental methods, employing electron microscopy, electrochemical measurements, and synchrotron X-ray measurements such as powder X-ray diffraction, X-ray absorption fine structure, and X-ray photoelectron spectroscopy. The hydroquinone reduction method proved to be an excellent route for the epitaxial growth of a Pt shell on the metal cores, leading to enhanced ORR activities.

A new method for deposition of nano sized titanium nitride on steels

Active screen plasma nitriding is a new and common method for deposition of Iron nitride. Since techniques such as Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD) and Plasma Assisted Chemical Vapor Deposition (PACVD) are usually applied in order to deposit the titanium nitride and each of these methods has its own problems, in this research active screen plasma nitriding method was introduced as a novel approach for deposition of nano sized titanium nitride. H11 tool steel samples were coated by plasma nitriding method at 550 °C for 5, 7.5 and 10 h, using three gas mixtures consisted of H 2/N 2 = 3, 1 and 1/3. Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) were employed to investigate the coating properties such as grain size, layer thickness and chemical composition. Results showed that the proportion of H 2 in the gas mixture was a crucial point in order to obtain a perfect coating. By increasing the coating time, the grain size and the layer thickness increased. XPS results showed that the coating was mainly consisted of TiN + TiN 0.1 together with a small amount of TiO 4.

Nanocomposite gold/poly(ethylene oxide)-like plasma polymers prepared by plasma-assisted vacuum evaporation and magnetron sputtering

A new method of deposition of nanocomposite gold/poly(ethylene oxide)-like thin films was investigated where gold was sputtered from an r. f. magnetron and poly(ethylene oxide)-like plasma polymer was simultaneously deposited via vacuum evaporation of conventional poly(ethylene oxide). Such method allows formation of the plasma polymer matrix with composition very close to that of precursor, a feature difficult to obtain in plasma polymerization processes. The films with different content of gold were prepared by varying the evaporation rate of poly(ethylene oxide) at constant power of the magnetron discharge. Chemical composition and cross-linking density of polymeric phase as well as the size distribution of gold nanoparticles were shown to be strongly dependent on the discharge power conditions. Stability of resultant nanocomposites in water was also studied. Such films are perspective for use in biomedical applications.

Electrochemical Codeposition of Thin Gold Nanoparticles/Sol−Gel Nanocomposite Films

We present a new method for deposition of thin nanocomposite films made of sol−gel-based Au nanoparticles using a single electrochemical step. Applying a negative potential to an electrode (indium tin oxide or stainless steel) immersed in a solution of gold nanoparticles stabilized with N-[3-(trimethoxysilyl)propyl] ethylenediamine (EDAS) caused the reduction of the protic solvent, which altered the pH and therefore catalyzed the deposition. The nanocomposite thin films were characterized by various techniques: the morphology and structure of the layers were examined by high-resolution scanning electron microscopy and atomic force microscopy; their thickness was determined by profilometry; and the permeability of the films was studied by electrochemistry. We found that homogeneous defect-free layers could be deposited only upon adding tetramethoxysilane (TMOS) to the deposition solution. Furthermore, we showed that the applied potential, the ratio between the TMOS and the Au nanoparticles, and the type of the substrate significantly affected the aggregation and density of the Au nanoparticles in the nanocomposite. Finally, by applying a positive potential to the nanocomposite films we succeeded to electrochemically dissolve the embedded Au nanoparticles, forming holes and channels. The oxidation treatment had a remarkable effect on the permeability of the film and exposed the electrode to faradic activity. This method seems to be of general applicability in templating of nanometer-sized objects in thin films.

In vitro testing of Nd:YAG laser processed calcium phosphate coatings

Nd:YAG laser cladding is a new method for deposition of a calcium phosphate onto metallic surfaces of interest in implantology. The aim of this study was to compare the biologic response of MG-63 human osteoblast-like cells grown on Ti-6Al-4V substrates coated with a calcium phosphate layer applied using different methods: plasma spraying as reference material and Nd:YAG laser cladding as test material. Tissue culture polystyrene was used as negative control. The Nd:YAG laser clad material showed a behaviour similar to the reference material, plasma spray, respective to cell morphology (SEM observations), cell proliferation (AlamarBlue assay) and cytotoxicity of extracts (MTT assay). Proliferation, as measured by the AlamarBlue assay, showed little difference in the metabolic activity of the cells on the materials over an 18 day culture period. There were no significant differences in the cellular growth response on the test material when compared to the ones exhibited by the reference material. In the solvent extraction test all the extracts had some detrimental effect on cellular activity at 100% concentration, although cells incubated in the test material extract showed a proliferation rate similar to that of the reference material. To better understand the scope of these results it should be taken into account that the Nd:YAG clad coating has recently been developed. The fact that its in vitro performance is comparable to that produced by plasma spray, a material commercially available for more than ten years, indicates that this new laser based method could be of commercial interest in the near future.

Novel technology for depositing a Pd–Ag alloy film on a tapered optical fibre for hydrogen sensing

Pd–Ag alloy thin films have attracted much attention in view of their potential applications in sensing hydrogen. In this paper we report on a new method of deposition of a high quality homogeneous Pd–Ag thin film on an optical fibre. The deposition method is used to fabricate sensors, which can detect hydrogen at very low concentrations (below 4%), by depositing a Pd–Ag thin film on tapered optical fibres. The deposition method and the complete method for fabrication of the tapered optical fibre sensors are presented in detail, as well as measurements of the hydrogen concentration in a nitrogen atmosphere made using the fabricated sensors. The sensors show good sensitivity and the optical responses of the sensors are in good agreement with theory.

Osteoblast growth on titanium foils coated with hydroxyapatite by pulsed laser ablation

Pulsed laser ablation is a new method for deposition of thin layers of hydroxyapatite (HA) on to biomaterial surfaces. In this paper, we report activity and morphology of osteoblasts grown on HA surfaces fabricated using different laser conditions. Two sets of films were deposited from dense HA targets, at three different laser fluences: 3, 6 and 9 J cm −2. One set of the surfaces was annealed at 575°C to increase the crystallinity of the deposited films. Primary human osteoblasts were seeded onto the material surfaces and cytoskeletal actin organisation was examined using confocal laser scanning microscopy. The annealed surfaces supported greater cell attachment and more defined cytoskeletal actin organisation. Cell activity, measured using the alamar Blue assay, was also found to be significantly higher on the annealed samples. In addition, our results show distinct trends that correlate with the laser fluence used for deposition. The cell activity increases with increasing fluence. This pattern was repeated for alkaline phosphatase production by the cells. Differences in cell spreading were apparent which were correlated with the fluence used to deposit the HA. The optimum surface for initial attachment and spreading of osteoblasts was one of the HA films deposited using 9°J cm −2 laser fluence and subsequently annealed at 575°C

Protective film by magnetic plasma polymerization on a Y–Ba–Cu–O superconductor

A new method of deposition of an organosilicon thin film by magnetic-controlling plasma polymerization has been successfully used to protect a YBa2Cu3O7−δ (YBCO) superconductor from corrosion. The organosilicon (hexamethyldisilane-HMDS) protective film obtained is homogeneous, compact, pinhole free, and highly crosslinked. The deposition rate of the polymer film increases rapidly first and then decreases, as radio frequency input power and HMDS monomer pressure increase, respectively. The deposition rate of a plasma polymer film with magnetic controlling is 20 times higher than that without magnetic controlling. The YBCO superconductor covered with an organosilicon film by magnetic-controlling plasma polymerization has been protected from corrosion in water over 48 h.

Langmuir-Blodgett films composed of monolayers of amphiphilic molecules and adsorbed soluble proteins

Langmuir-Blodgett (LB) films with the structure, monolayer of surfactant 1/adsorbed protein layer/monolayer of surfactant 2, were deposited and studied by ellipsometry, IR spectroscopy and atomic force microscopy (AFM) techniques. To avoid protein denaturation, a new method of deposition was applied in which protein molecules avoided contact with the air-water interface and were adsorbed onto the hydrophilic surface of the deposited monolayer in optimal conditions. Five surfactants, cytochrome c, alcohol dehydrogenase and glutathione S-transferase (GST) were used in these structures. The results of measurements on the enzymatic activity of GST show that soluble proteins can be included in LB films using the proposed method without considerable denaturation.

Thin films comparable with WC-Co cemented carbides as underlayers for hard and superhard coatings: the state of the art

A new method for deposition of barrier underlayers, which completely prevent Co penetration to the substrate surface and are highly compatible with WC-Co cemented carbides, has been developed. It allows deposition of thin hard continuous, highly adherent and defect-free TiCN-based films by the use of high energy titanium ions. The method ensures deposition without any damage of the cemented-carbide substrate or its decarburization, leading to formation of the η phase near the surface layer. As a result, CVD TiC, TiCN, TiN etc. coatings can be deposited onto cemented carbides preliminarily plated with barrier underlayers almost without a decrease in transverse rupture strength. Special additional interlayers are applied for enhancement of the adhesion between the underlayers and plasma CVD diamond coatings, resulting in excellent resistance of the near-surface layer of the cemented-carbide substrate with these coatings to high static loading when subjected to indentation.

New method of deposition of biomolecules for bioelectronic purposes

A laser induced plasma vaporization and ionization technique is proposed for electric field assisted deposition of proteins. Experiments were carried out depositing thick layers of lysozyme on metal, creating submillimeter patterns. The enzymatic activity of horseradish peroxidase deposited by this method was tested, together with that of the enzyme laccase from a micro-organism. The applicability of this method to the construction of nanometric patterns for bioelectronic purposes is discussed.

Deposition of metallic films by laser ablation of oxides in hydrogen atmosphere

Pulsed laser ablation from oxide surfaces in hydrogen atmosphere is shown to be a powerful new method for deposition of high quality metal films. Specifically, the cases of ablation from CuO and α-Fe2O3 are studied. By examining the effects of hydrogen pressure, laser energy density, and the substrate temperature on the nature of the deposited films, optimum parameters have been identified for realization of high quality films of metallic Cu and Fe.