Cathode Sputtering Research Articles

Biopolymer Composites with Ti/Au Nanostructures and Their Antibacterial Properties.

In this study, we have aimed at the preparation and characterization of poly-l-lactic acid (PLLA) composites with antibacterial properties. Thin bilayers of titanium and gold of various thickness ratios were deposited on PLLA by a cathode sputtering method; selected samples were subsequently thermally treated. The surface morphology of the prepared composites was studied by atomic force, scanning electron, and laser confocal microscopy. The chemical properties of the composites were determined by X-ray photoelectron and energy-dispersive X-ray spectroscopy in combination with contact angle and zeta potential analyses. The antibacterial properties of selected samples were examined against a Gram-negative bacterial strain of E. coli. We have found that a certain combination of Au and Ti nanolayers in combination with heat treatment leads to the formation of a unique wrinkled pattern. Moreover, we have developed a simple technique by which a large-scale sample modification can be easily produced. The dimensions of wrinkles can be tailored by the sequence and thickness of the deposited metals. A selected combination of gold, titanium, and heat treatment led to the formation of a nanowrinkled pattern with excellent antibacterial properties.

PEGylated Gold Nanoparticles Grafted with N-Acetyl-L-Cysteine for Polymer Modification

The subjects of this work were the enhancement and determination of the stability and other properties of gold nanoparticles (AuNPs) in an aqueous solution, gold nanoparticle immobilization, and further surface grafting on polyethylene naphthalate (PEN). Gold nanoparticles in PEG with a subsequent water solution addition were prepared using cathode sputtering; for the subsequent surface activation, two different solutions were used: (i) sodium citrate dihydrate (TCD) and (ii) N-acetyl-L-cysteine (NALC). The aim of this work was to study the effect of the concentration of these solutions on AuNPs stability, and further, the effect of the concentration of gold nanoparticles and their morphology, and to describe the aging process of solutions, namely, the optical properties of samples over 28 days. Stabilized AuNPs were prepared in an N-acetyl-L-cysteine (NALC) system and subsequently immobilized with NALC. The surface chemistry modification of AuNPs was confirmed using HRTEM/EDS. Gold nanoparticles were successfully immobilized with NALC. Grafting of the modified PEN from a solution of colloidal gold stabilized in the PEG–H2O–NALC system led to the polymer surface functionalization.

Chemical deposition and mechanical application of semiconductors thin films

Features and main technological methods of forming thin layers of semiconductor materials by methods of chemical deposition and mechanical application are analyzed. The disadvantages of thermal sputtering and cathodic sputtering of thin films in vacuum for multicomponent semiconductor compounds are indicated. Features of chemical deposition of semiconductor films from the gas (steam) phase are presented. Such deposition involves the transfer of source material from the evaporator zone with higher temperature in the form of volatile compounds to the colder surface of the substrate, where the film growth occurs as a result of reaction of transported compounds or their decomposition. It is shown that the growth of the film during chemical vapor deposition is a process of layer-by-layer condensation of atoms or molecules, with the advantageous difference that during chemical deposition the latter are formed as a result of a heterogeneous chemical reaction when there is no need for average free path length of the gas molecules to be larger than the size of the deposition chamber, i.e. no need for critical degree of vacuum. Chemical deposition of thin films from solution is characterized as a process of precipitation of solute which occurs due to the fact that the ionic product exceeds the product of solubility, i.e. it is greater than the constant value characteristic of a saturated solution in the equilibrium state. We emphasize, that chemical deposition from an water solution allows to obtain homogeneous in thickness and structure fine-grained non-textured mechanically stable polycrystalline films with good adhesion to substrates and the required set of properties. The method of pulverization with subsequent pyrolysis is described. This is deposition from intracomplex organometallic compounds, which is based on thermally stimulated reactions between clusters of atoms, chemically active substances of liquid or vapor phase. The method of electrolytic deposition on electrically conductive substrates is characterized. The method is using appropriate salt solutions by co-deposition of individual components, or by deposition on the cathode of one of the components with its subsequent interaction with others present in the solution. We also describe the method of obtaining epitaxial thin films of semiconductor deposition materials. We note that the analyzed methods or their modifications are necessary tool today to create thin-film semiconductor structures with predetermined properties. In the same time, in each particular case the features of each method of obtaining thin semiconductor films should be comprehensively evaluated and, depending on the chemical composition, structure, topology and complex of expected properties, the most effective method should be applied.

A positively biased external anode for energy control of plasma ions: hollow cathode and magnetron sputtering discharge

The performance of a positively biased external ring anode in combination with a hollow cathode (HC) discharge or a magnetron sputtering (MS) discharge, both with a Ti cathode and with Ar as working gas, is investigated. Plasma and floating potential increase as function of anode voltage. Energy-resolved mass spectrometry reveals that the kinetic energy of argon and titanium ions is enhanced by a positive anode voltage allowing for an effective energy control of plasma ions.

Effect of Substrate Bias on the Crystal Structure and Morphology of Barium Strontium Niobate Films Grown by RF Cathode Sputtering

Barium strontium niobate films have been grown on MgO(001) substrates by single-step rf cathode sputtering of a ceramic target with the stoichiometric composition Sr0.5Ba0.5Nb2O6 in an oxygen atmosphere under various conditions (at different substrate biases). It has been shown that, depending on its polarity, the substrate bias either increases or reduces the flux of structure-forming elements to the substrate and, as a consequence, changes the growth rate, without impairing the surface morphology or surface perfection of the film or producing impurity phases. The mechanisms underlying the observed general relationships are discussed.

Formation of Nitrogen Doped Titanium Dioxide Surface Layer on NiTi Shape Memory Alloy.

NiTi shape memory alloys are increasingly being used as bone and cardiac implants. The oxide layer of nanometric thickness spontaneously formed on their surface does not sufficiently protect from nickel transition into surrounding tissues, and its presence, even in a small amount, can be harmful to the human organism. In order to limit this disadvantageous phenomenon, there are several surface engineering techniques used, including oxidation methods. Due to the usually complex shapes of implants, one of the most prospective methods is low-temperature plasma oxidation. This article presents the role of cathode sputtering in the formation of a titanium dioxide surface layer, specifically rutile. The surface of the NiTi shape memory alloy was modified using low-temperature glow discharge plasma oxidation processes, which were carried out in two variants: oxidation using an argon + oxygen (80% vol.) reactive atmosphere and the less chemically active argon + air (80% vol.), but with a preliminary cathode sputtering process in the Ar + N2 (1:1) plasma. This paper presents the structure (STEM), chemical composition (EDS, SIMS), surface topography (optical profilometer, Atomic Force Microscopy—AFM) and antibacterial properties of nanocrystalline TiO2 diffusive surface layers. It is shown that prior cathodic sputtering in argon-nitrogen plasma almost doubled the thickness of the produced nitrogen-doped titanium dioxide layers despite using air instead of oxygen. The (TiOxNy)2 diffusive surface layer showed a high level of resistance to E. coli colonization in comparison with NiTi, which indicates the possibility of using this surface layer in the modification of NiTi implants’ properties.

Development of a one-dimensional differential deposition system for X-ray mirror figure correction

A thin-film deposition system was developed for the surface coating of X-ray mirrors of up to 1 m in length. With two coating process areas and four sputtering cathodes, various combinations employing a single layer, multilayered, and co-sputtered thin films are possible. Furthermore, it is possible to correct and modify the mirror surface shape by controlling the speed of the substrate stage. In this study, to evaluate the performance of the proposed coating system, the static coating distribution was measured to check the vertical direction. In a 10 mm area, a 0.9% peak-to-valley error and 0.2% root mean square error occurred. A differential deposition test was also performed for the horizontal direction (stage scan direction). In this study, arbitrary shapes were deposited on 100-mm and 400-mm-long mirrors. After removing the measurement error, the deposition error was less than 1 nm (peak-to-valley). The results demonstrate that this system can correct the surface of an X-ray mirror with ultra-high precision.

CONTROL OF IONIZATION PROCESSES IN MAGNETRON SPUTTERING SYSTEM BY CHANGING MAGNETIC FIELD CONFIGURATION

This work is devoted to measuring the function of the distribution of charged particles of gas-discharge plasma in a magnetron sputtering system under conditions of non-potential "earth". Measurements are carried out with the help of a three-electrode probe, which is installed in the cathode sputtering zone, with unsafe electrodes and housing. The selection of the analyzed particles was carried out through a screen located under floating potential. Effect of additional magnetic insulation anode of MSS МАG-5 on ion and electron distribution functions was investigated.

Microstructure and adhesion characteristics of duplex coatings with different plasma‐nitrided layers and a Cr‐Al‐Ti‐B‐N physical vapor deposition coating

AbstractA duplex treatment consisting of plasma nitriding (PN) and physical vapor deposition (PVD) significantly improves the thermal, tribological, and corrosion resistance of forming tools, and especially if they are intended for applications subject to high mechanical loads. This study investigates the influence of nitriding on the properties of a conventionally heat‐treated AISI D2 tool steel, coated with a Cr‐Al‐Ti‐B‐N layer, while the effect of the presence or absence of a compound layer is discussed. PN is performed at 510–520°C using different N2‐H2 gas mixtures. The Cr‐Al‐Ti‐B‐N layers are deposited at 480°C using a combination of cathodic arc evaporation and magnetron sputtering. The samples are characterized using electron probe microanalysis with wavelength‐dispersive X‐ray spectroscopy, optical and scanning electron microscopy, glancing‐angle X‐ray diffraction, surface hardness measurements, profilometry, Rockwell indentation, and scratch tests. These techniques reveal relationships between the depth gradient of the chemical composition and microstructure of the nitrided interlayer, the adhesion of the PVD coating, and the hardness of the tool steel. Although the PVD process induces a structural transformation in the compound layer, this transition does not have a negative influence on the adhesion of the PVD coating.

Modelling of multiple-hollow-cathode-discharge laser

A laser tube configuration for metal vapour lasers with hollow cathode sputtering is theoretically studied. The construction consists of a main hollow cathode and a few hollow cathode holes. Optimal conditions for laser oscillation are realised inside the main cathode, while the current density in the side hollow cathodes is higher and the discharges that occur in the hollow cathode holes can be used as additional sources of metal atoms produced by sputtering. To study the processes in the discharge and the unique capabilities of the construction the PLASIMO modelling platform is used.

Shaping the structure and properties of titanium and Ti6Al7Nb titanium alloy in low-temperature plasma nitriding processes

Plasma nitriding of titanium Grade 2 and Ti6Al7Nb titanium alloy at 730 °C was used to produce nitrided surface layers with an outer zone consisting of nanocrystalline titanium nitride - TiN, and a Ti2N zone right above the αTi(N) diffusion area. The paper presents a comparison of structure (TEM, SEM), phase composition (XRD, SAED) surface topography (AFM, optical profilometer), corrosion (potentiodynamic method), tribological properties (‘ball-on-disc’), and adhesion (scratch-test) of TiN + Ti2N + αTi(N) type nitrided surface layers produced on Grade 2 titanium and Ti6Al7Nb titanium alloy using conventional glow-discharge nitriding (so called glow discharge nitriding at the cathode potential) and with the use of an ‘active screen’ (glow discharge nitriding at plasma potential). A reduction of cathodic sputtering in the plasma potential process made it possible to produce surface layers maintaining a high smoothness of the titanium surfaces. Due to the low surface roughness and the high compressive residual stress of the sample after nitriding at plasma potential, ‘ball-on-disc’ test results showed the lowest coefficient of friction and the lowest penetration depth for this layer and very good adhesion of the layer to the substrate – i.e. Ti6Al7Nb titanium alloy. Nitriding of titanium alloy at cathode potential increased the corrosion potential value and slightly decreased corrosion current density. The corrosion current density of the sample nitrided at plasma potential was similar to initial state Ti6Al7Nb titanium alloy. The nitriding process type (cathode potential or plasma potential) used to produce TiN + Ti2N + αTi(N) surface layers on Ti6Al7Nb titanium alloy has an influence on the microstructure of the layer, its residual stress, in particular its TiN outer titanium nitride zone, its thickness, and on its properties such as wear and corrosion resistance.

Tribological Properties of Ti-Doped Diamond-Like Carbon Coatings Under Boundary Lubrication With ZDDP

Abstract Diamond-like carbon (DLC) coatings containing 0.7%, 5.8%, and 23.3% Ti were deposited via pulsed cathodic arc deposition and magnetron sputtering on AISI 316L stainless steel substrates. The varied Ti content was controlled by setting Ti target current at 3, 5, and 7A. The composition, microstructure, mechanical, and tribological properties of Ti-doped DLC (Ti-DLC) coatings were investigated using X-ray photoelectron spectroscopy, Raman spectroscopy, nanoindentation, and ball-on-disc tribometer. The results show that TiC formed when Ti content in the coating was higher than 5.8 at% and the ID/IG ratios increased gradually with the increasing Ti content. Ti-DLC with 0.7 at% Ti had the highest H/E and H3/E2 ratios and exhibited optimal tribological properties under lubrication, especially when zinc dialkyldithio-phosphate (ZDDP) was contained in the oil. Furthermore, ZDDP tribofilms played an important role in wear reduction by protecting the rubbing surfaces against the adhesion and suppressing the tribo-induced graphitization of DLC coatings.

ВТОРИЧНАЯ ПЕРЕРАБОТКА ЛИТЫХ ТРУБНЫХ КАТОДОВ ПРИ ПОЛУЧЕНИИ МЕТАЛЛОПОРОШКОВОЙ КОМПОЗИЦИИ ДЛЯ ГАЗОТЕРМИЧЕСКОГО НАПЫЛЕНИЯ ПОКРЫТИЙ

The paper presents the results of structural studies of metal-powder compositions (MPC) from the VSDP-3 alloy, as well as heat-resistant atmospheric-plasma powder coatings, developed at the FSUE «VIAM». As blanks for sputtering the MPC, standard charge blanks and exhausted resource cast tube cathodes for ion-plasma deposition were used. It was found that MPC obtained by sputtering cathodes and coatings deposited by sputtering these MPC are not inferior in properties to standard MPC and coatings. At the same time, the cost of such MPC and coatings can be 20–40% lower.

Диэлектрические и сегнетоэлектрические свойства тонких гетероэпитаксиальных пленок SBN-50

The phase transformations and ferroelectric characteristics of thin heteroepitaxial barium-strontium niobate SBN-50 films grown by RF cathode sputtering in an oxygen atmosphere were studied using dielectric spectroscopy and scanning probe microscopy (in the modes of force microscopy of the piezoresponse and Kelvin modes). It is shown that the films are characterized by a low surface roughness, an average size of ferroelectric domains of ~ 100 nm, and spontaneous polarization directed from the substrate to the film surface. Differences in the magnitude of the surface potential signal and its relaxation for the regions polarized at +10 V and –10 V were established. The nature of the change in the dielectric parameters in the temperature range T = 275–500 K indicates that the material belongs to ferroelectric relaxors. The reasons for the established regularities are discussed.

A Hollow-Cathode Ion Source in Glow Discharge Mass Spectrometry

The paper proposes a new glow discharge ion source based on a hollow cathode. The proposed source produces a denser plasma than the previously used glow discharge sources. It is shown experimentally that the maximum rate of cathode sputtering of a conducting solid sample in a hollow cathode ~25 mm in diameter is achieved when the sample has the shape of a rod with a diameter of 2–4 mm and a length of 10–15 mm and is placed along the axis of the cathode cavity. If a cover with a hole is placed on the cathode cavity, a plasma bunch is formed near the hole (a “plasma plug”), which resists the flow of argon from the hollow cathode. The pressure in the discharge chamber decreases, and the glow discharge is concentrated in the cathode cavity. This results in a decrease in the background level in the glow discharge source by approximately two orders of magnitude. The mechanism of formation and extraction of ions from a glow discharge ion source is considered. The ions formed in the glow discharge plasma form two oppositely directed ion flows in the source, one of them with an ion energy of 100 eV or higher. These ions, accelerating in the region of the cathode potential drop, are directed to the cathode, bombard the analyzed sample, and spray it. The second flow of low-energy ions is drawn from the same region of negative luminescence and is transported in the opposite direction, that is, to the surface of the discharge chamber-anode due to ambipolar diffusion. These ions are extracted from a hole in the anode chamber of a conventional ion source by an accelerating voltage and used for mass spectral analysis. The use of a hollow cathode with a plasma plug, the effect of ambipolar diffusion, and a modified Pierce lens makes it possible to increase the luminosity of the glow discharge source by more than one order of magnitude.

Tuning the Perpendicular Magnetic Anisotropy in Co/Pt Multilayers Grown by Facing Target Sputtering and Conventional Sputtering

Magnetic properties of [Co(0.4 nm)/Pt(0.7 nm)]5 multilayers are tailored by controlling the sputtering voltage during the growth of cobalt layers by a facing target cathode. It is shown that increasing sputtering voltage up to 150 V leads to an improved crystalline texture and this results in larger magnetic anisotropies and out-of-plane coercive fields. At a higher cathode voltage of 540 V however crystalline texture quality slightly worsens and this is accompanied by a decrease in the effective anisotropy. Using facing target cathode sputtering, the crystalline structure of the multilayers can be controlled without applying any heat treatment and this can be used to optimize the magnetic properties of Co/Pt multilayers for specific applications.

Magnetic field optimization and high-power discharge characteristics of cylindrical sputtering cathode

基于高功率脉冲磁控溅射(HiPIMS)技术开发的筒形溅射阴极, 配合电磁系统可有效地提升等离子体的输运效率. 然而电磁系统的引入反作用于筒内放电特性, 从而使靶面放电面积和放电强度无法同时维持. 鉴于此, 本文通过调整磁场布局, 研究了靶面切向(横向)磁场和法向(纵向)磁场对靶面放电的作用规律, 优化后靶面切向磁场分布更加均匀, 磁场强度高于40 mT的靶面区域占比由51%增至67%, 同时法向峰值强度外移, 强度由73 mT增至96 mT. 采用Ar/Cr体系放电发现：相同工艺条件下, 优化后的溅射阴极辉光变亮, 靶电流增大, 放电面积变宽, 放电特性得到显著提升. 利用等离子体整体模型仿真和发射光谱仪检测发现优化后离子电流和光谱强度得到明显提升, Cr粒子密度提高一倍, 增至2.6 × 10²⁰ m^–3, 且离化率上升至92.1%, 同时输出离子通量提高近一倍, 实现了靶面放电与离子输出的双促进.

Study of the influence of the substrate material on the phase composition and thickness of Ti-Pb coatings deposited by a magnetron

The structure of coatings deposited by reactive magnetron sputtering of Ti and Pb cathodes on substrates from Mo, 30HGSA and 304 steel was studied by X-ray diffraction. The thickness of the coatings was determined by the difference between the CTE of the coating and the substrate, which is maximum for Mo coating and minimum for 304 steel, for which the thickest coating was found, consisting of tetragonal modifications of PbO.

The Effect of a Ba0.2Sr0.8TiO3 Sublayer on the Structure and Electric Characteristics of Lead Zirconate Titanate Films on the Si(001) Substrate

Metal–ferroelectric–semiconductor Pb(ZrTi)O3/Ba0.2Sr0.8TiО3/Si(001) heterostructures have been synthesized by radiofrequency cathode sputtering. It has been established that the Pb(ZrTi)O3 films are single-phase and textured and the degree of predominance of one crystallographic orientation over another (110 or 001) is determined by the Ba0.2Sr0.8TiO3 sublayer thickness. It is shown that, by varying the sublayer thickness and/or the amplitude of one period of the external bipolar field effect, one can obtain different electric states of the structure, which can give rise to creating memory cells, including multilevel ones.

The impact of H2 and N2 on the material properties and secondary electron yield of sputtered amorphous carbon films for anti-multipacting applications

Amorphous carbon thin films were prepared by direct current hollow cathode sputter deposition in Ar discharge with the injection of small amounts of H2 and/or N2. The influence of these additives on the film properties with particular focus on the application as a coating for electron cloud mitigation in particle accelerators is characterized by optical spectroscopy, X-ray photoelectron spectroscopy, and secondary electron yield (SEY) measurements. The SEY maximum increased from initially 0.98 with pure Ar in the gas discharge up to 1.38 at 0.5% H2 while the addition of 1% of pure N2 enabled to reduce it to 0.88. The simultaneous addition of N2 to the H2 containing discharge allowed an average SEY maximum reduction of 20%. The optical bandgap revealed a correlation between the increase/decrease of the bandgap and the SEY increment/reduction for H2/N2 addition. The surface composition changes and the resulting modification of the sp2/sp3 ratio correlate with the changes in SEY and optical properties. The obtained results highlight the potential of intentionally injected N2 to counteract the detrimental effect of the inevitable H2 partial pressure in the coating systems during the production of amorphous carbon thin films for anti-multipacting applications in particle accelerators.