Magnetron Sputtering Plasma Research Articles

Combination of Plasma Jet and Magnetron Sputtering─A New Method for Preparing Thin Ni–Co–Mn Oxide Coatings on Stainless Steel Meshes and Their Efficiency in the Total Oxidation of Volatile Organic Compounds

Combination of Plasma Jet and Magnetron Sputtering─A New Method for Preparing Thin Ni–Co–Mn Oxide Coatings on Stainless Steel Meshes and Their Efficiency in the Total Oxidation of Volatile Organic Compounds

As-deposited and dewetted Cu layers on plasma treated glass: Adhesion study and its effect on biological response

Improving the adhesion of nanosized copper films to a glass substrate is vital for their application in electronics and medicine, as it enhances their overall reliability. For this purpose, we employed Ar plasma etching (240 s) and magnetron sputtering to create copper layers on a glass substrate. Furthermore, we investigated the effect of subsequent solid state dewetting (at 300 °C) of Cu nanolayers on the interface stability. Increasing the sputtering time resulted in elevated copper concentration, UV-Vis absorption, conductivity, and surface roughness. The as-deposited and dewetted samples exhibited very good wettability with water contact angles below 60°. Importantly, plasma treatment improved the adhesion of the Cu layers to the glass. Subsequent dewetting accelerated surface diffusion and the oxidation of Cu atoms, causing structural and morphological changes. The presence of CuO after dewetting caused loss of the surface plasmon resonance (SPR) band in the UV-Vis spectrum and a decrease in sample conductivity due to the transformation of the copper layer from a metal to an oxide. Biological testing revealed a more pronounced bactericidal effect for the as-deposited Cu layer against E. coli and S. epidermidis on contrary to dewetted samples. The similar cytotoxic trend was observed for human dermal fibroblasts and hepatocytes. Nonetheless, biological testing confirmed better cell adhesion on dewetted Cu layers compared to the as-deposited ones. Therefore, our copper nanostructured samples could find application as antibacterial coatings of biomedical devices.

Multicoated Flexible Indium Tin Oxide Electrodes Fabricated Using Magnetron Sputtering and Arc Plasma Ion Plating for Flexible Perovskite Solar Cells.

High-performance flexible Sn-doped In2O3 (indium tin oxide, ITO) electrodes were fabricated using a multicoating process on colorless polyimide (CPI) substrates for flexible perovskite solar cells (FPSCs). The effects of different coating sequences on the electrical, optical, and mechanical properties of the flexible ITO electrodes were thoroughly investigated after preparing them with direct-current magnetron sputtering (DMS) and arc plasma ion plating (APIP). Although both the sputtered ITO (SITO)/arc ion-plated ITO (AITO) film and the AITO/SITO film showed similarly low sheet resistance (18.69-25.29 Ω/sq) and high optical transmittance (94.96-96.85%), the coating sequence significantly affected the mechanical flexibility of the multicoated ITO films. The 120 nm-thick SITO/AITO electrode exhibited small outer and inner critical bending radii (3 mm and 3 mm, respectively) compared to the AITO/SITO electrode (4 and 5 mm, respectively). Owing to better adhesion of the arc-ion-plated ITO bottom layer and the amorphous structure of the top SITO layer, the SITO/AITO electrode exhibited excellent mechanical flexibility and durability. In addition, an FPSC using the SITO/AITO electrode achieved a higher power conversion efficiency (15.09%) than that with the AITO/SITO electrode (13.22%). This improvement was attributed to its high transmittance, low sheet resistance, smooth surface morphology, and enhanced hole collection efficiency. These findings highlight the efficacy of the combined DMS and APIP multicoating process for fabricating high-quality flexible ITO electrodes for high-performance FPSCs.

Preparation and tribologic properties of Ti and Zr nitride multilayer coatings

This paper focuses on synthesis and characterization of Zr/Ti and Ti/Zr nitride multilayer coatings by magnetron plasma sputtering to enhance the tribologic properties. The synthesis of nitrides was achieved by non-reactive deposition using Ti or Zr nitride targets or by reactive deposition using Ti or Zr targets in the presence of nitrogen. The formation of nitride layers was highlighted by XRD, EDX and XPS investigations, while the tribologic properties were made with HFRR equipment. The tribological study showed that the coefficient of friction and wear scar diameter decrease in multilayer films with zirconium nitride as the upper layer.

Synergistic Enhancement of Efficient Perovskite/Quantum Dot Tandem Solar Cells Based on Transparent Electrode and Band Alignment Engineering

AbstractPerovskite‐based tandem solar cells have demonstrated high potential for overcoming the Shockley–Queisser limit. Routine bandgap (RBG, ≈1.55 eV) perovskites have achieved a perfect balance between efficiency and stability. The narrow bandgap (NBG) candidates for RBG perovskite‐based tandem devices are very limited. Lead sulfide (PbS) colloidal quantum dots (CQDs) are a promising partner due to their broad absorption spectra. However, the efficiency of RBG perovskite/QD tandem devices still lags behind. Herein, efficient RBG perovskite/QDs four‐terminal tandem photovoltaics are successfully implemented through synergistic enhancement from transparent electrode and band alignment Engineering. For tin doped indium oxide (ITO) electrodes, their conductivity and near‐infrared transparency are leveraged using magnetron sputtering and reactive plasma deposition (RPD) methods. Furthermore, instead of traditional zinc oxide, aluminum‐doped zinc oxide (AZO) is developed to enhance the carrier extraction capability of PbS QD bottom cells. Based on the above enhancements, ≈0.95 eV PbS solar cells achieve a record efficiency of 14.14%. Integrated with the front semi‐transparent perovskite solar cells, the four‐terminal perovskite/QD tandem device reaches a record efficiency of 26.12%. The synergistic combination of the RBG perovskite and NBG QD devices provides promising prospects for tandem photovoltaics.

A field programmable gate array based Langmuir probe system for measurement of plasma parameters at 500kHz in a high-power impulse magnetron sputtering plasma.

By utilizing Field Programmable Gate Arrays in a configuration similar to that of the Mirror Langmuir Probe, it is possible to bias a single probe at three precise voltages in sequence. These voltages can be dynamically adjusted in real-time based on the measured plasma electron temperature to ensure the transition region is always sampled. The first results have been obtained by employing this method and have generated real-time outputs of electron temperature, ion saturation current, and floating potential on a low temperature pulsed-DC magnetron at 500kHz. These results are in good agreement with the analysis of a conventionally swept Langmuir probe. This probe is designed with the intention of being implemented on MAST-U to aid in the study of exhaust physics and enable further investigation into filamentary behavior.

Improved corrosion resistance and cytotoxicity of nickel‐based alloy using novel plasma processing technique

AbstractIn this study, we address challenges in the biocompatibility of nickel‐based (NiCr) alloys, prevalent in the dental industry, due to toxic metal ion release impacting corrosion resistance and cytotoxicity. Employing magnetron sputtering and cathodic cage plasma nitriding (CCPN), a duplex plasma treatment (DPT) is introduced to the NiCr alloy. The novel approach enhances surface morphology, notably reducing ion leakage compared with untreated samples. Specifically, the CCPN‐TiN‐treated sample significantly improves corrosion resistance and minimizes metal ion leakage. This transformative DPT emerges as a promising solution for surface modification, particularly mitigating toxic ion leaching in aggressive electrolytes. This research demonstrates a major stride in enhancing NiCr alloy biocompatibility, emphasizing the vital role of innovative surface modification techniques for biomedical applications and challenges.

Construction of Co-ZIF-derived CoS2@Cu hollow heterogeneous nanotube array for the detection of hydrazine in environmental water samples

As a neurotoxin, it is necessary to establish a low cost, stable and sensitive method for the quantitative detection of hydrazine. Using Co-ZIF (zeolite imidazole framework) nanorods as precursor, CoS2 hollow nanotube array heterogeneous structure loaded with Cu nanoparticles were prepared on carbon cloth (CC) by etching, calcination and plasma magnetron sputtering (CoS2@Cu HNTA/CC). As a self-supporting electrode, its hollow heterogeneous structure provides a large area of electron transfer channel for the oxidation of the food pollutant hydrazine. In addition, bimetallic synergies and in situ N doping regulated the electronic structure of CoS2@Cu HNTA/CC, and thus significantly improved the electrical conductivity and catalytic activity. As an efficient hydrazine sensor with a wide linear range of 1 μM L−1-10 mM (1 μM-1 mM and 1 mM–10 mM), its sensitivity and the limit of detection are 7996 μA mM−1 cm−2, 3772 μA mM−1 cm−2 and 0.276 μM (S/N = 3), respectively. This study provides a new strategy for the construction of MOFs (Metal Organic Framework)-derived bimetallic composites and their application in electrochemical sensing.

High temperature oxidation behaviors of Al/Cr composite coating on Ti2AlNb alloy

The Al/Cr coatings were deposited on Ti2AlNb alloy by magnetron sputtering and double glow plasma alloying technology to improve the oxidation resistance. The morphology of the protective coating was investigated by scanning electron microcopy and the phase composition of the coating was analyzed using x-ray diffraction. The results suggested that the protective coating with multilayer structure was dense and homogeneous. The formation of Cr inner diffusion layer was beneficial to the bonding strength between the coating and substrate, which was attributable to the double glow technology. The oxidation behaviors of Al/Cr coating were investigated by the isothermal oxidation tests for 100 h at 700 °C, 800 °C and 900 °C, respectively. The results indicated that the protective coating showed a lower oxidation rate. At 700 °C, the Al2O3 oxidation products were formed on the surface of coating at high temperature, which were dense and homogeneous against oxygen diffusion. With the increase of oxidation temperature, the external diffusion of Cr element reacted with oxygen to form Cr2O3, which provided the further protection. As for 900 °C, the volatile CrO3 was formed by the reaction of the external diffusion of Cr and Cr2O3, and the oxidation products Al2O3 and Cr2O3 continued to provide protection for Ti2AlNb alloy.

Analysis of a second peak of electron density observed in high-power impulse magnetron sputtering plasma using a Langmuir probe

Plasma characteristics of a high-power impulse magnetron sputtering (HIPIMS) for copper deposition were investigated using a time-resolved Langmuir probe to explore HIPIMS discharge physics. Various discharge frequencies and pulse widths were employed while operating the HIPIMS in a constant current mode. Waveforms of the HIPIMS cathode current remained constant throughout the HIPIMS voltage pulse. It was found that electrons exhibited a bi-Maxwellian energy distribution both during and after the HIPIMS pulse. After the HIPIMS pulse, plasma density built up to a second peak while the bulk electron temperature quickly decreased. By examining the effect of pulse width and discharge frequency on the temperature of hot electrons through Langmuir I–V curves, it is suggested that the hot electron ionization contributed to the occurrence of the second peak.

Surface Modification of NiTi Alloy with Sputtered Tantalum Coatings to Improve its Hardness, Corrosion Resistance and Biocompatibility

In this research, titanium alloys including smart nitinol (NiTi) were studied. The (NiTi) alloy tends to emitting (Ni) toxic ions due to its low resistance to corrosion within the body conditions over time. For (NiTi) coating process, the magnetron plasma sputtering (DC) technique was used with Aragon gas ratio of (90%) and Oxygen of (10%) in order to coat the alloy with Tantalum and its Oxide (Ta2O[Formula: see text] thin films. This is one of the methods used to improve the biocompatibility and better adhesion stability of the membrane on the (NiTi) surface, since Tantalum and its oxides are biocompatible and are not affected by the body fluids. Hardness, corrosion and biocompatibility were tested. The results showed improvement in the nominated properties using this coating technique. The hardness for the non-coated sample was (630 Kgf/mm[Formula: see text], meanwhile, the coated sample recorded (762 Kgf/mm[Formula: see text] using sputtering power of (25 W) with a thickness of (226 nm). Tantalum and its precipitated oxides on a pillar of thickness (90.4–226 nm) also exhibited a biocorrosion enhancement, when it was immersed in a Simulated Body Fluid (SBF). The corrosion rate for the non-coated sample was (1.204 × 10[Formula: see text], meanwhile for the coated sample, its value was (3.453 × 10[Formula: see text] at sputtering power of (15 W), considered as the lower corrosion rate. The scanning electron micrographs also showed an increase in the biocompatibility for the coated nitinol alloys (NiTi) in comparison with the non-coated, ones since it showed a clear formation of Hydroxyapatite (HA) on the sample surface after immersion in the SBF. This behavior was confirmed by the XRD measurements, which presented higher HA peaks on the coated samples surface in comparison with the non-coated samples.

A retarding field thermal probe for combined plasma diagnostics

The wide variety and ever-growing applications of plasma processes in research and industry require an equally growing diversity and accessibility of suitable plasma diagnostics. The plasma parameters and the tailoring thereof strongly influence the outcome of thin film deposition, plasma etching, or surface treatments, to name only a few. To further enhance the determination of different fluxes of species, their energies, and behaviour influencing a surface process, a custom-built combination of two commonly used diagnostics was developed. With a retarding field energy analyzer, one can obtain the ion energy distribution in a plasma by measuring the current at the collector depending on the applied voltage at the scan grid. A passive thermal probe determines the energy flux density coming from a process plasma by measuring the temperature change of a dummy substrate. In this study, we present a retarding field energy analyzer where a passive thermal probe substitutes the collector. By doing so, we can determine the energy distribution of the charged ions, their energy flux density at a certain potential, and the power deposited onto a substrate. Another advantage is that the thermal probe can even measure the power deposited by incoming (fast) neutrals and of the background gas when the grids keep away the ions. Hence, combining these two powerful diagnostics yields information neither can deliver on their own. The probe has been tested in three different plasma environments: ion beam source, magnetron sputtering and radio frequency discharge plasma.

Dual low pressure plasma process for SiCN:H thin films deposition: A comparative study

SiCN:H thin films have large possibilities of applications due to their versatile chemical and physical properties. Plasma Assisted Chemical Vapor Deposition (PACVD) process is widely used for SiCN:H deposition. Here we discuss on the potentialities of dual Electron Cyclotron Resonance (ECR) and Radio Frequency Magnetron Sputtering (rf MS) plasmas coupling for SiCN:H deposition in Ar/N2/Si(CH3)4 gas mixture. The study is carried out by varying the autopolarisation voltage Vbias of the silicon target. ECR plasma gives low deposition growth rate about 50 nm/h. The films are transparent. SiCN nanopillars with high aspect ratio are obtained. Rf MS plasma gives high deposition growth rate up to 2200 nm/h. The films are opaque in the near UV and transparent in the visible depending on their thickness. The optical index at 630 nm is 1.95, the Tauc's band gap is 3.0 eV and do not change with Vbias. Dual ECR/rf MS plasma gives high deposition growth rate up to 2300 nm/h. The films are transparent. The optical index varies between 1.7 and 2.05 at 630 nm and the Tauc's band gap decreases linearly between 4.75 and 3.4 eV with Vbias. Dual ECR/rf MS plasma coupling is a very promising PACVD process for thin films deposition.

Azimuthal ion movement in HiPIMS plasmas—part I: velocity distribution function

Magnetron sputtering discharges feature complex magnetic field configurations to confine the electrons close to the cathode surface. This magnetic field configuration gives rise to a strong electron drift in azimuthal direction, with typical drift velocities on the order of 100 km s−1. In high power impulse magnetron sputtering plasmas, the ions have also been observed to follow the movement of electrons with velocities of a few km s−1, despite being not magnetized. In this work, we report on measurements of the azimuthal ion velocity using spatially resolved optical emission spectroscopy, allowing for a more direct measurement compared to experiments performed using mass spectrometry. The azimuthal ion velocities increase with target distance, peaking at about 1.55 km s−1 for argon ions and 1.25 km s−1 for titanium ions. Titanium neutrals are also found to follow the azimuthal ion movement which is explained with resonant charge exchange collisions. The experiments are then compared to a simple test-particle simulation of the titanium ion movement, yielding good agreement to the experiments when only considering the momentum transfer from electrons to ions via Coulomb collisions as the only source of acceleration in azimuthal direction. Based on these results, we propose this momentum transfer as the primary source for ion acceleration in azimuthal direction.

Assessment of thermomechanical stability of DLC films deposited by Ne-HiPIMS technology for high-temperature applications

Enhancement of the thermomechanical stability of diamond-like carbon (DLC) coatings is highly demanded by the automotive industry due to graphitization at higher temperatures. This work is devoted to the assessment of the thermomechanical stability of annealed DLC films deposited by increasing Ne up to 50% in high-power impulse magnetron sputtering (HiPIMS) plasma, followed by the evaluation of their tribomechanical properties. The tribological performance of the films was assessed by room-temperature tribological tests after annealing the films, and by high-temperature tribological test at 300 °C in ambient atmosphere. The microstructure and chemical compositions of the films were analyzed, and the hybridization state of the annealed films was determined by x-ray absorption near-edge spectroscopy (XANES). The wear mechanism involved in both high-temperature and annealed films tribological tests with the steel counterpart was the combination of abrasion and adhesion. It was observed that all the films demonstrated stable tribomechanical performance by annealing up to 500 °C, while from 600 °C, the film deposited in pure Ar plasma demonstrated poor tribomechanical performance. In contrast, increasing Ne to 50% in plasma led to an increase in the thermomechanical stability of DLC films to more than 700 °C, and resisting graphitization up to 800 °C.

Highly response gas sensor based the Au-ZnO films processed by combining magnetron sputtering and Ar plasma treatment

The excellent and promising gas sensors not only have high response, but also can be easily integrated with other semiconductor devices to form an intelligent chip. In order to realize this goal, an effective strategy is proposed to combine the magnetron sputtering and Ar plasma treatment. As a result, a high-performance sensor based on Au-ZnO films is achieved at the optimal technology parameter, with high response (Ra/Rg) of 190 to 100 ppm isopropanol (IPA), rapid response/recovery speed of 1 s/18 s, and low detection limit of 100 ppb at 300 °C. Moreover, the mechanisms of the improvement on the sensing properties of the as-fabricated sensor are discussed. The present work provides new ideas for the future development of integrating gas sensors with functional circuits to form a smart chip that can perform data acquisition, processing and storage.

Ionization of sputtered material in high power impulse magnetron sputtering plasmas—comparison of titanium, chromium and aluminum

The ionization of sputtered species in high power impulse magnetron sputtering of titanium, chromium, and aluminum targets is analyzed using Abel-inverted spectroscopic imaging to locate the position of ionization. From the spatial emission of neutrals, it is deduced that most of the sputtered titanium particles become ionized within 0.5 mm distance from the target, whereas sputtered aluminum or chromium can travel much further through the discharge before ionization occurs. Probe measurements reveal the reason for this difference to be the unusually high electron temperature of around 4.5 eV for titanium compared to 2.6 eV and 1.5 eV for aluminum and chromium as the target material, respectively. These probe measurements are then compared to a global model derived from the ionization region model. Excellent agreement between model and measurements can be reached, but only if the transport physics for the confinement of the species is adjusted. Using the model, the difference between the three discharges can be traced back to be mostly caused by the sputter yield. Thus, we propose that ionization in discharges with low-yield materials should generally be expected to occur closer to the target surface, leading the ions to be affected more strongly by the electric field across the magnetic trap region, resulting in a more severe deposition rate loss compared to high-yield materials.

Ag NPs@PDMS nanoripple array films as SERS substrates for rapid in situ detection of pesticide residues

The large-area fabrication of flexible and transparent surface-enhanced Raman scattering (SERS) substrates with high performance by a facile and efficient method is still challenging. Here, we demonstrated a large-scale, flexible and transparent SERS substrate composed of PDMS nanoripple array film decorated with silver nanoparticles (Ag NPs@PDMS-NR array film) prepared by a combination of plasma treatment and magnetron sputtering. The performances of SERS substrates were characterized by rhodamine 6G (R6G) using a handheld Raman spectrometer. The optimal Ag NPs@PDMS-NR array film exhibited high SERS sensitivity, with a detection limitation of R6G reaching 8.20 × 10−8 M as well as excellent uniformity (RSD = 6.8%) and batch-to-batch reproducibility (RSD = 2.3%). In addition, the substrate showed outstanding mechanical stability and good SERS enhancement by backside illumination, thus it was suitable for in situ SERS detection on curved surfaces. The detection limit of malachite green on apple and tomato peels was 1.19 × 10−7 and 1.16 × 10−7 M, respectively, and quantitative analysis of pesticide residues could be realized. These results demonstrate that the Ag NPs@PDMS-NR array film has great practical potential in rapid in situ detection of pollutants.

Plasma Sputtering of Nano-CaTiO3 Thin Film Applied for Surface Modification of Co–Cr Alloy

A biocompatible and corrosion-resistant coating was progressed by depositing a thin film of calcium titanate (CaTi[Formula: see text] on CoCr-based alloy substrate using a radiofrequency magnetron plasma sputtering process to improve the characteristics of the interface between the thin-film coating and the CoCr alloy substrate. In this technique, the best power was previously observed at 225 W to get good coating film deposition properties. This power was applied to a deposited thin film of CaTiO3 on a heated CoCr-based alloy at [Formula: see text]C using an argon gas atmosphere with purity (99.8%) under vacuum 1.00E-02 Torr. Different deposition rates and times were used to observe nanofilm, the thicknesses of (50 nm, 80 nm, 110 nm and 140 nm). Field-emission scanning electron microscopy (FESEM) was applied to study surface morphologies. X-ray diffraction (XRD) was used to study the crystalline structure of thin films deposited. The Vickers Micro-Hardness tests were implemented on each specimen. Vitro electrochemical corrosion tests (open circuit potential, Tafel polarization curve and cyclic polarization) of the coated and uncoated specimens were done, to find the optimal state that gives excellent resistance to corrosion in a simulated body fluid environment. The results of the experiments showed that as the thickness of the thin films increased, so did the hardness measurements. An enhancement in corrosion resistance also was clearly observed at a thickness of 140 nm CaTiO3 thin-film compared with uncoated and coated specimens at other nanothicknesses.

DC pulsed plasma magnetron sputtering of CdO/Cu/CdO multilayers thin films for self-cleaning and optoelectronic applications

In this study, CdO/Cu/CdO multilayers thin films were organized on glass substrates with different Cu intermetallic layer thickness engaging DC plasma magnetron sputtering. The optoelectronic properties and structural characteristics of the multilayers at various Cu intermetallic layer thicknesses which were varied from 4 to 16 nm were explored. The calculated band gap was reduced from 2.66 eV to 2.48 eV as the Cu intermetallic layer thickness increased from 4 to 16 nm. The refractive index and coefficient of extinction of CdO/Cu/CdO multilayers increased with increasing the Cu intermetallic layer thickness. The resistivity is reduced from 1.8 × 10−2 Ω cm for CdO single layer to reach a value of 2.7 × 10−4 Ω cm for CdO/Cu (16 nm)/CdO multilayer. Further, the sheet resistance is decreased from 1000 to 13.8 Ω/sq. with the variation in Cu intermetallic layer thickness from 0 to 16 nm. CdO/Cu (4 nm)/CdO multilayer film recorded the best figure of merit (2.3 × 10−4 Ω−1). After sunlight illumination for the multilayers, the surface wettability was improved and the contact angle recorded lowest value of nearly 24° for CdO/Cu (8 nm)/CdO and CdO/Cu (12 nm)/CdO.