Sputtering Source Research Articles

RETRACTED ARTICLE: Probe measurements of a plasma hollow cathode discharge used as a sputter source for copper thin film

RETRACTED ARTICLE: Probe measurements of a plasma hollow cathode discharge used as a sputter source for copper thin film

Watermelon-like texture lithium titanate and silicon composite films as anodes for lithium-ion battery with high capacity and long cycle life

Buffering the volume expansion of Si particles is considered to be an effective method for preparing Si based electrode with high capacity and prominent cycling performance. Here, watermelon-like texture Li4Ti5O12 (LTO) and Si composite film electrode was synthetized by magnetron co-sputtering using spinel LTO powder and crystalline Si wafer as the sputtering source. In the composite film electrode, LTO acts as watermelon pulp and Si acts as watermelon seed. The obtained composite film electrode endows a high reversible capacity of ~800 mAh g−1 at 100 mA g−1 with a capacity retention ~76% after 1000 cycles. The extraordinary electrochemical characteristics of the composite film electrode could be attributed to the role of LTO in watermelon pulp which prevents electrolyte from contacting with Si nanoparticles directly, easing the stress caused by periodic volume change and the multi-interface between LTO and Si as well as supplying efficient and rapid transport routes for Li-ions. The outcomes reveal the watermelon-like texture composite film is a promising high energy density and splendid long cycle stability anode material for lithium-ion batteries.

Synthesis and physical characterization of magnetron sputtered Graphene-CdS bilayer

CdS/Graphene Nano composites have been extetinsively investigated in the field of basic industrial research and electronic device applications because of their unique physical, chemical properties and photo stability under visible‐light irradiation. In this study, we explore the electrical properties of Cadmium sulfide with the addition of graphene. CdS/Graphene hybrid was fabricated by simple RF magnetron sputtering method using CdS as a sputtering source. The hybrid material formation and structural properties of Graphene, CdS, CdS/Graphene have been discussed using XRD, FTIR, Raman, and UV–vis spectroscopy techniques. Herein, we present a facile and efficient method for hybridization of CdS Nano-sphere with graphene Nano sheet and subsequent investigation of enhancement of current of the hybrid material. Field emission scanning electron microscopy (FESEM) micrographs reveal the formation of CdS nanospheres and homogeneous scattering on the surface of graphene sheets. The UV absorption spectrum of CdS/Graphene hybrid presented a red-shifted. The enhancement in the current of CdS/Graphene hybrid has been observed due to the generation of electron-hole pairs. Also, current-voltage (I-V) characteristics of an as-grown thin film of the hybrid are conducted using 4-point probe measurement and revealed their semiconducting nature with a drastic enhancement of electrical conductivity.

Study of the tungsten sputtering source suppression by wall conditionings in the EAST tokamak

The steady fusion plasma operation is constrained by tungsten (W) material sputtering issue in the EAST tokamak. In this work, the suppression of W sputtering source has been studied by advanced wall conditionings. It is also concluded that the W sputtering yield becomes more with increasing carbon (C) content in the main deuterium (D) plasma. In EAST, the integrated use of discharge cleanings and lithium (Li) coating has positive effects on the suppression of W sputtering source. In the plasma recovery experiments, it is suggested that the W intensity is reduced by approximately 60% with the help of ∼35 h Ion Cyclotron Radio Frequency Discharge Cleaning (ICRF-DC) and ∼40 g Li coating after vacuum failure. The first wall covered by Li film could be relieved from the bombardment of energetic particles, and the impurity in the vessel would be removed through the particle induced desorption and isotope exchange during the discharge cleanings. In general, the sputtering yield of W would decrease from the source, on the bias of the improvement of wall condition and the mitigation of plasma-wall interaction process. It lays important base of the achievement of high-parameter and long-pulse plasma operation in EAST. The experiences also would be constructive for us to promote the understanding of relevant physics and basis towards the ITER-like condition.

Direct measurement of thrust induced by a magnetron sputtering source

The direct measurement of thrust imparted by a magnetron sputtering source operated in argon is performed using a pendulum thrust balance immersed in vacuum, where various target materials are tested. The imparted thrust is clearly changed by the target material, while the ion density, which is expected to be mostly the argon ions, is unchanged. The maximum thrust-to-power ratio of 10–12 mN/kW is obtained for a copper target, which has a maximum sputtering yield in the target materials tested here. It is shown that the plasma pressure force is much smaller than the detected thrust, demonstrating the thrust generation via the material ejection by the sputtering process.

The Interface Characterization of 2-Mercapto-1-methylimidazole Corrosion Inhibitor on Brass

This work presents a detailed surface analytical study and surface characterization, with an emphasis on the X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) analyses of 2‑mercapto‑1‑methylimidazole (MMI) as a corrosion inhibitor for brass. First, the electrochemical measurements demonstrated a corrosion inhibition effect of MMI in a 3 wt.% NaCl solution. Next, the formation of the MMI surface layer and its properties after 1 month of immersion was analyzed with attenuated total reflectance–Fourier-transform infrared spectroscopy, atomic force microscopy, field-emission scanning electron microscopy, and contact angle analysis. Moreover, to gradually remove the organic surface layer, a gas cluster ion beam (GCIB) sputtering source at different accelerated voltages and cluster sizes was employed. After each sputtering cycle, a high-resolution XPS analysis was performed. Moreover, an angle‑resolved XPS analysis was carried out for the MMI-treated brass sample to analyze the heterogeneous layered structure (the interface of the MMI organic/inorganic brass substrate). The interface properties were also investigated in detail using ToF-SIMS for spectra measurements and 2D imaging. Special attention was devoted to the possible spectral interferences for MMI‑related species. The thermal stability of different MMI-related species using molecular-specific signals without possible spectral interferences was determined by performing a cooling/heating experiment associated with ToF-SIMS measurements. It was shown that these species desorbed from the brass surface in the temperature range of 310–370 °C.

Influence of Substrate Rotational Speed on the Structural and Optical Properties of Sputtered Gd-Doped ZnO Thin Films

Rare-earth element of gadolinium (Gd) were successfully doped into zinc oxide (ZnO) using dual sputter source of DC and RF sputtering. The substrate rotation speed was controlled from 1 rpm to 9 rpm to investigate their effects on the properties of the films in order to achieve a great feature of thin film. XRD profiles confirmed the c-axis orientation with structure of ZnO hexagonal wurtzite. No peaks related to secondary phases were observed. The intensity of dominant peak showed increment upon improvement of substrate rotation speed. The incorporation of Gd into ZnO structure was further confirmed by composition element form EDX with average atomic percentage of 3 at. % for all the films. Surface topology from AFM images showed the grain size has increased with the higher speed of substrate rotation. Gd-doped ZnO thin films indicated good transparency with an average transmittance above 90 % regardless of substrate rotation speed. The bandgap has a slight decrease from 3.06 eV to 3.03 eV with an increment speed of rotational substrate. These findings further imply that the substrate rotation speed has a significant influence on the structural and optical properties of the sputtered thin films.

Impact of the gas dynamics on the cluster flux in a magnetron cluster-source: Influence of the chamber shape and gas-inlet position.

Although producing clusters by physical methods offers many benefits, low deposition rates have prevented cluster-beam deposition techniques from being adopted more widely. The influence of the gas aerodynamics inside the condensation chamber of a magnetron cluster-source on the cluster throughput is reported, leading to an improved understanding of the influence of gas aerodynamics on cluster transport. In the first part of this paper, the influence of the carrier gas's inlet position on the cluster flux is studied. In particular, two inlet configurations were investigated, i.e., from the rear of the chamber and from within the magnetron sputtering source. It was found experimentally that the latter configuration can lead to an increased cluster flux, under the same conditions of gas pressure and power applied to the magnetron. This behavior is explained with the help of simulations. In the second part of this paper, the gas dynamics behavior inside four chamber shapes, namely, two cylindrical shapes with different cross-sectional diameters and two conical shapes with different apex angles, was simulated. The modeling showed that the fraction of clusters successfully leaving the aggregation zone can be increased by up to eight times from the worst to the best performing chamber geometries studied. Finally, the cluster throughput was determined experimentally using a quartz microbalance in two of the four chamber designs. It was found that the cluster flux increased up to one order of magnitude, reaching ∼20 mg/h for a condensation chamber with a smaller cross section and a conical exit.

Instrument for in situ hard x-ray nanobeam characterization during epitaxial crystallization and materials transformations.

Solid-phase epitaxy (SPE) and other three-dimensional epitaxial crystallization processes pose challenging structural and chemical characterization problems. The concentration of defects, the spatial distribution of elastic strain, and the chemical state of ions each vary with nanoscale characteristic length scales and depend sensitively on the gas environment and elastic boundary conditions during growth. The lateral or three-dimensional propagation of crystalline interfaces in SPE has nanoscale or submicrometer characteristic distances during typical crystallization times. An in situ synchrotron hard x-ray instrument allows these features to be studied during deposition and crystallization using diffraction, resonant scattering, nanobeam and coherent diffraction imaging, and reflectivity. The instrument incorporates a compact deposition system allowing the use of short-working-distance x-ray focusing optics. Layers are deposited using radio-frequency magnetron sputtering and evaporation sources. The deposition system provides control of the gas atmosphere and sample temperature. The sample is positioned using a stable mechanical design to minimize vibration and drift and employs precise translation stages to enable nanobeam experiments. Results of in situ x-ray characterization of the amorphous thin film deposition process for a SrTiO3/BaTiO3 multilayer illustrate implementation of this instrument.

Design of a liquid-phase magnetron sputtering small-sized source for the vacuum coating system MVTU-11-1MS

The relevance of magnetron sputtering to obtain conductive metallized coatings with a thickness of up to tens of micrometers is indicated. Attention is paid to the features of magnetron sputtering with a liquid target. It is noted that this process is currently being implemented using magnetrons with size from 3” to 6”. The design flaws of the existing NMSA-52M magnetron and its mounting unit to the chamber of the vacuum coating system MVTU-11-1MS are considered. The design of a magnetic system with an increased value of magnetic induction on a 2” magnetron surface has been developed. The magnetron sputtering source were designed: a housing, a chamber mounting unit and a cover. As a result, a variant of the improved design of the magnetron sputtering source is presented, which takes into account the disadvantages of the existing NMSA-52M magnetron.

Accelerated/reduced growth of tungsten fuzz by deposition of metals

From the helium (He) plasma irradiations to tungsten performed in the Magnum-PSI device, the effects of deposition of metals on the helium-plasma induced fiberform nanostructures (fuzz) are discussed. It was found that fuzz was not formed at the center of the plasma cylinder if there were significant metallic impurities from the source. Deposition of metallic impurities (mainly molybdenum and copper) counteracted the growth of fuzz. In addition to the effects of metals from the source, we installed a sputtering source near the sample to replicate the deposition environment in fusion devices. The thickness of fuzzy layer was ∼7 µm, which was about five times greater than that without deposition, at the He flux of 1.3×1026 m−2, suggesting that the growth rate of fuzz layer was significantly accelerated due to the deposition of tungsten.

Realizing Double Graded CIGSe Absorbers With the R2R Hybrid-CIGSe-Process

This article presents an approach for industrial roll-to-roll (R2R) deposition of Cu(In,Ga)Se2 (CIGSe) thin films on stainless steel foil for use as absorber layers in flexible thin-film solar cells. The hybrid-CIGSe-deposition-process combines magnetron sputtering with evaporation techniques and allows the realization of a double graded CIGSe layer, reaching a conversion efficiency of currently up to 14.0% (w/o antireflective coating). The influence of different power settings of the individual magnetrons on the gallium profile is described. For a deeper understanding of differences between a static and an R2R process, a calculated flux diagram is presented. In the second part of this contribution, the homogeneity of the industrial scale samples is discussed by comparing the change in CGI and GGI over the foil width of 30 cm. The hybrid-CIGSe-deposition-process excels in a straightforward scalability for industrial usage due to the application of planar magnetron sputtering sources as metal vapor supply.

Tuning the microstructure of the Pt layers grown on Al[formula omitted]O[formula omitted] (0001) by different sputtering methods

High-quality epitaxial Pt films are usually grown by molecular beam evaporation (MBE) techniques, where the deposited atoms reach the substrate with typical thermal energies. To obtain a good epitaxial growth, the substrate is kept at elevated temperatures ranging between few hundred to thousand degrees. While the epitaxial quality improves at higher substrate temperatures, above a critical temperature Volmer-Weber growth mode starts and causes a rough film morphology. Here, we use a new type of facing target cathode (FTC) to grow Pt onto Al2O3 (0001) substrates. In contrast to conventional sputtering sources, FTC sources provide adatoms with lower kinetic energies, but higher growth rates compared to MBE. In this study, the crystal structure of Pt films is compared for different substrate temperatures. Using FTC, flat Pt films with low strain and a morphology that is either nanocrystalline or highly epitaxial could be grown through proper choice of substrate temperature.

Gas-phase synthesis and deposition of metal-bipyridine complex [M-bpy1-2]+ (M = Ag, Cu).

Controllable synthesis of organometallic clusters in the gas phase is a topic of reasonable interest with precisely tunable properties depending on sizes, compositions, and intra-cluster charge-transfer interactions. Here, we have prepared small Agn+ and Cun+ clusters by using a customized magnetron sputtering (MagS) source and observed the gas-phase reactions with 2,2'-bipyridine. It is found that the small silver and copper clusters readily react with bipyridine and form products of [M-bpy1-2]+ (M = Ag, Cu). Quantum chemistry calculations reveal that the bipyridine in both [Ag-bpy1-2]+ and [Cu-bpy1-2]+ takes on cis-conformation with altered N-C-C-N dihedral angles, which is in contrast to the trans-conformation of a free 2,2'-bipyridine molecule itself. In order to unveil the principle of conformational transition, we have fully studied the interactions between the nitrogen atoms of bipyridine and the cationic Ag+ and Cu+, calculated the donor-acceptor orbital overlaps, and analyzed the correlation of their frontier molecular orbital energy levels. Furthermore, by using a soft-landing strategy, we have managed to deposit the [Cu-bpy2]+ complex onto the glass substrates coated with Ag nanoparticles, and recorded the surface-enhanced Raman scattering spectra.

Effect of bias voltage on the microstructure and properties of Nb-DLC films prepared by a hybrid sputtering system

Diamond-like carbon (DLC) films with Nb doping were fabricated by a hybrid sputtering system comprising a high power impulse magnetron sputtering unit and a pulse direct current magnetron sputtering source. The effect of bias voltage on the morphology and chemical bonding characteristic of the Nb-DLC films were investigated. Results showed that the bias voltage played a significant role on the microstructure of the films. The surface morphology revealed a granular microstructure and the average size of these granules decreased with increasing bias voltage. Accordingly, the cross-sectional morphology evolved from an apparent columnar structure to a compact and dense nanocomposite structure with NbC nanocrystallites embedding in the amorphous carbon matrix at a high bias voltage. The integrated area ratio of the D and G peaks (ID/IG) of the Raman spectra decreased with increasing bias voltage, indicating the sp3‒C bonding fraction was improved in the films. The mechanical properties including hardness and elastic modulus, internal stress and elastic recovery, as well as the wettability property of films with different bias voltages were also investigated. With increasing bias voltage, the high sp3‒C fraction, modulated stress and formed hard carbide phase were all conducive to the enhancement of the hardness. Furthermore, all the films exhibited hydrophobic behavior and this tendency weakened at relatively high bias voltage conditions.

Effects of a cathode fall region on deposition rate of copper atoms in Dc plasma sputtering source

A theoretical investigation was carried out to show the effect of the length of the cathode fall region on the deposition rate of copper atoms on a substrate using dc plasma sputtering source. The effects of the discharge voltage (−1 to −3 kV) and argon gas pressure (1 × 10–2 to 5 × 10–1 mbar) on the length of the cathode fall region of the proposed plasma source were investigated. The flux energies of gas ions, neutral’s gas atoms and electrons in one dimension were calculated to determine the length of the cathode fall region, total current density and the rate of deposition of copper atoms. The results show that the length of the cathode fall region increases when low gas pressure is used at high values of the discharge voltage for the plasma source. There is also a relationship between the length of the cathode fall region and the rate of deposition of copper atoms on the substrate, where the deposition rate increased by 76% when the cathode fall length increased by 120% at the discharge voltage −3 kV and the pressure of gas 1 × 10–2 mbar.

External magnetic field guiding in HiPIMS to control sp3 fraction of tetrahedral amorphous carbon films

Amorphous carbon films have many applications that require control over their sp3 fraction to customise the electrical, optical and mechanical properties. Examples of these applications include coatings for machine parts, biomedical and microelectromechanical devices. In this work, we demonstrate the use of a magnetic field with a high-power impulse magnetron sputtering (HiPIMS) source as a simple, new approach to give control over the sp3 fraction. We provide evidence that this strategy enhances the deposition rate by focusing the flux, giving films with high tetrahedral bonding at the centre of the deposition field and lower sp3 fractions further from the centre. Resistive switching appears in films with intermediate sp3 fractions. The production of thin amorphous carbon films with selected properties without the need for electrical bias opens up applications where insulating substrates are required. For example, deposition of sp3 rich films on polymers for wear resistant coatings as well as fabrication of resistive switching devices for neuromorphic technologies that require tuning of the sp3 fraction on insulating substrates are now possible.

Hybrid Physical Chemical Vapour Deposition (HPCVD) of Superconducting MgB2 Thin Films on three Dimensional Copper Substrates

The present work reports the design, development and application of a novel Hybrid Physical Chemical Vapour Deposition (HPCVD) technique for depositing MgB2 thin films, with potential superconductivity, directly on three dimensional (3D) surfaces. A novel solenoid magnetron based set up was used for depositing MgB2 thin films on 3D surfaces of Cu tube. Mg rod was used as the sputter target and source of Mg while high purity BBr3 was used as a novel boron precursor, which was injected into the system using Argon as carrier gas. The plasma mediated decomposition of BBr3 in presence of H2 gas was followed by chemical reaction between Mg and B atoms to deposit MgB2 film on the substrate. Samples were characterized by SEM, EDX, XRD and SQUID techniques. SEM-EDX confirmed deposition of a homogeneous, pore free and dense MgB2 film, while XRD analysis revealed the film to be polycrystalline and multiphasic rather than being purely c-axis oriented. Superconductivity analysis carried out using SQUID measurements indicated a sharp transition with Tc value of 39 K. From the M-H hysteresis loop, the lower critical field Hc1 and critical current density Jc at 4.2 K were calculated to be 700 Oe and 3.5 x 10 7 A/cm 2 , respectively.

Determining High-Temperature Oxidation Resistance of Ti-Al-Cr-Si-N Based Nitride Thin Coatings Deposited on Titanium Alloys

This article considers the possibility of applying thin Ti-Al-Cr-Si-N based nitride thin coatings (up to 10 microns) for increasing the heat-resistance of titanium alloy blades without altering their aerofoil. It presents the results of testing samples, which were coated by using different ratios of the parameters of main element deposition simultaneously from various sputtering sources, as well as an assessment of the efficiency of these coatings in terms of oxidation at temperatures of 750–850°С.

Development and analysis of frits for enamelling AA2024, AA6082 and AA7075 aluminium alloys

AbstractThis study reports the development of frits with different composition, time, and firing temperature for mitigating the corrosion of AA2024, AA6082, and AA7075 aluminium alloys in chloride‐containing solutions. The melting points of the frits were determined using a heating microscope, while the thermal expansion was measured using dilatometry. Several frits were prepared, of which seven were coated on AA2024, AA6082 and AA7075 aluminium alloys. The corrosion resistance of the coated samples was tested in 5 wt% NaCl solution at 25°C using potentiodynamic curve measurements. The corrosion resistance of the coated samples increased compared with the respective uncoated aluminium alloys. The composition and in‐depth homogeneity of the best‐performing coated samples were confirmed using a gas cluster ion beam sputtering source associated with X‐ray photoelectron spectroscopy analysis. Furthermore, O2+ sputtering was performed in association with time‐of‐flight secondary ion mass spectrometry to describe the three‐dimensional composition of the frits.