Sputtering Target Research Articles

Influence of Deposition Parameters of ITO Films on the Performance of HJT Solar Cells

TCO (transparent conductive oxide) films are widely used in solar cells due to the characteristics of transparency and conductivity. In this paper, ITO (indium tin oxide) transparent conductive films are prepared on common slides by DC magnetron sputtering, and the preparation process and characteristics of ITO films are studied. The target for sputtering is ITO, with the mass ratio of In203 and Sn02 was 90% : 10%. The sheet resistance, carrier concentration, and carrier mobility of ITO films are measured and analyzed by a UV-Vis spectrophotometer, four-point probe, and Hall effect measurement system. By changing the oxygen content, deposition temperature, and sputtering power to studied the effects on the light transmittance and electrical conductivity of the ITO films, further studied the effects on the HJT (heterojunction with intrinsic thin film) solar cells, and finally determined the appropriate preparation parameters. Results show that the resistance is 6 . 4 ∗ 10 − 4 Ω • cm , the light transmittance is beyond 90.6%, efficiency is 23.78%, and bifacial ratio is 84% when oxygen content is 2.2%, sputtering power is 3 kw, and deposition temperature is 190°C.

Carbon modified silver thin-film catalysts for electrochemical reduction of CO2 to syngas with tunable H2/CO ratio

This study investigates carbon (C)-modified silver (Ag) thin film catalysts for electrochemical syngas production. The Ag-C catalyst is synthesized using a co-deposition process with separate C and Ag sputtering targets. It is found that co-deposition with C increases nucleation rate during film growth, which reduces particle size and increases the surface area, as well as increasing the selectivity for the hydrogen evolution reaction (HER). A 10-fold improvement in the geometric current density is obtained for the Ag-C thin film relative to Ag due to a high abundance of active sites, and a H2/CO ratio between 1.4 and 2.5 is attained within the potential range of − 0.6 to − 1.0 V. vs RHE. Thus, regulating the C concentration allows the H2/CO ratio to be tuned while maintaining a surface architecture that permits large geometric current densities, both being desirable properties for catalysts used in syngas applications.

Mechanical performance of high-entropy (AlCrNbSiTi)N films fabricated by high-power impulse magnetron sputtering over a wide compositional window

We designed nine distinct compositions of AlCrNbSiTi high-entropy alloy targets by adjusting the Al, Cr, Nb, and Ti contents, while maintaining the Si content at 7.7 at.%. We fabricated (AlCrNbSiTi)N films using the high-power impulse magnetron sputtering (HiPIMS) technique. By analyzing the microstructure and properties of the films, we have identified an expanded compositional window. This expansion enables (AlCrNbSiTi)N films with varying composition ratios to consistently demonstrate excellent mechanical properties. This consistency proves advantageous in terms of both sputtering target preparation and coating applications. In this study, all films had a single face-centered cubic (NaCl-type) structure with a crystallite size of ∼6 nm and lattice constant of ∼4.22 Å. The hardness of the films varied between 25.9 and 27.6 GPa. The thickness of the oxide layer formed when the films were annealed at 800 °C for 2 h under atmospheric conditions was approximately 30 nm, regardless of the composition. We also examined the cutting properties of (AlCrNbSiTi)N coatings on carbide cutting tools. Under dry milling conditions and extended cutting distances, the (AlCrNbSiTi)N coatings exhibited a remarkable reduction in flank wear length, with reductions of 78%, 64%, and 68% when compared to the commercial coatings TiN, TiAlN, and AlTiN, respectively. Furthermore, these coatings remained intact without peeling during milling on a 304 stainless steel workpiece. This research demonstrates that the combination of HiPIMS and high-entropy (AlCrNbSiTi)N could provide hard coatings with excellent performance during cutting. The characteristics of the coatings are attributable to the fineness and high density of the films deposited by HiPIMS and the synergistic lattice distortion and cocktail effects, which are similar in the compositional window of the designed alloy system.

Te doping effects on the ferromagnetic performance of the MnGe/Si quantum dots grown by ion beam sputtering deposition

Dilute magnetic MnGe quantum dots (QDs) have been a popular research topic due to their great potential application on spintronics and their natural compatibility with today's highly developed silicon-based complementary metal oxide semiconductor (CMOS) technology. However, the relatively low Curie temperature impedes their ability to maintain the ferromagnetic phase and creates difficulty for their practical application in spintronics at room temperature. Here, we report the first preparation of the Te-doped dilute-magnetic Mn0.064Ge0.895Te0.041/Si QDs by using the ion beam composite target sputtering technique. Growth temperature and deposition thickness dependent QDs density and magnetic properties were investigated systematically. The experimental results indicate that the QD density of Mn0.064Ge0.895Te0.041/Si sample increases first and then reduces with the deposited thickness, while the QDs' diameters increase monotonously from 10.18 ± 0.21–33.6 ± 0.34 nm. Curie temperature of 369 K observed in Mn0.064Ge0.895Te0.041 QDs is higher than that of 295 K observed in Mn0.061Ge0.939 counterparts grown at the same conditions. Correspondingly, the saturation and residual magnetization in the former are much higher than in the latter. The ferromagnetic enhancement can be attributed to that the nonpolar Mn0.064Ge0.936 QDs transform into Rashba polar Mn0.064Ge0.895Te0.041 QDs with the doping of Te ions, which obviously promotes the exchange coupling between holes and Mn atoms. Our work provides a practical approach for improving the ferromagnetism and Curie temperature of silicon-based diluted magnetic semiconductor QDs.

Preparation of high-purity copper through vacuum distillation

Copper is capable of maintaining strong competitiveness in the metal materials market for its prominent ductility, thermal conductivity, and electrical conductivity. As more rigorous purity requirements of industrial sputtering targets and aerospace have been raised, the clean and efficient production of high-purity copper turns out to be an urgent problem over the past few years. In this paper, the possibility of removing impurities from copper melt was investigated by integrating theoretical calculations and experiments, and the separation coefficient and vapor-liquid equilibrium phase diagram of copper and impurity elements were determined and plotted using the molecular interaction volume model (MIVM). Moreover, the effects of the distillation temperature, the holding time, and the system pressure on the experimental results were discussed. As indicated by the results, with the rise of the temperature and with the extension of the holding time, the purity of copper was first increased and then decreased, and the purity of residual copper reached 99.9993% at 1473 K temperature, 1.5 h holding time, and 5 Pa pressure, and the method effectively separated impurities from copper raw materials. Besides, no waste water or waste gas emission was generated in the experiment.

Magnetron deposition of barium hexaferrite films from a target of stoichiometric composition

A technique has been proposed for obtaining films of barium hexaferrite on sapphire with the (0001) orientation using the high-frequency magnetron sputtering of a stoichiometric BaFe12O19 target followed by annealing The performed X-ray diffraction analysis and Raman spectrometry showed the possibility the possibility of crystallization of oriented films without using correction of the target composition.

Magnetron Deposition of Barium Hexaferrite Films from a Target of Stoichiometric Composition

A technique is proposed for obtaining films of barium hexaferrite on sapphire with (0001) orientation by high-frequency magnetron sputtering of a stoichiometric BaFe12O19 target followed by annealing. The X-ray diffraction analysis and Raman spectrometry carried out showed the possibility of crystallization of oriented films without using correction of the target composition.

Preparation of ZnO Piezoelectric Thin-Film Material for Ultrasonic Transducers Applied in Bolt Stress Measurement

The measurement of bolt preload by using ultrasound can be accurate, convenient, and can realize the real-time monitoring of the change in the residual axial stress of a bolt during use. In order to realize the ultrasonic measurement of bolt preload, the use of zinc oxide (ZnO) piezoelectric thin-film material as an ultrasonic transducer material to stimulate an ultrasonic signal on the bolt is a feasible solution. In this paper, we choose to use RF magnetron sputtering technology to prepare ZnO piezoelectric thin-film materials and study the effects of sputtering power and target substrate distance on the structure and ultrasonic properties of ZnO piezoelectric thin films during the preparation process, in order to lay the foundation for realizing the application of ZnO piezoelectric thin films in the field of bolt preload measurement. The experimental results show that too-large sputtering power or too-small target substrate distance will result in the particles having too much kinetic energy during sputtering and exhibiting a structure of multiorientation growth, which excites ultrasonic longitudinal–transverse waves. A sputtering power of 600 W, sputtering time of 4 h, and target substrate distance of 100 mm are ideal experimental parameters for a ZnO piezoelectric thin-film material to be excited by an ultrasonic longitudinal wave signal, and its ideal operating frequency is 41 MHZ. These research results of bolt stress detection demonstrate good application prospects.

Correlation between crystallite size, resistance to oxidation, and phase transformation of germanium-doped Fe3O4 nanocrystalline thin films by using a sputtering target of α-Fe2O3

We investigated the correlation between the crystallite size, resistance to oxidation, and phase transition of Ge-doped Fe3O4 nanocrystalline thin films. We prepared thin films on water-cooled glass substrates by radiofrequency sputtering with Ge-tipped α-Fe2O3 ceramic disks as targets. The addition of Ge caused a reductive phase transition from α-Fe2O3 with a corundum structure to Ge-doped Fe3O4 with an inverse spinel structure, resulting in a crystallite size of <10 nm. We annealed three samples with average sizes of 5, 8, and 10 nm by changing Ge addition concentrations at 673 K in air for up to 323 days until reaching near-thermal equilibrium. All samples maintained their magnetization at almost a constant value over long-term heat treatment. The results of Raman spectroscopy and optical transmittance spectroscopy suggest that there was a phase transition to Ge-doped γ-Fe2O3 at 5 nm, Ge-doped Fe3−δO4 with iron vacancies δ at 8 nm, and Ge-doped Fe3O4 at 10 nm. In other words, we retained Fe3O4 down to a relatively small crystallite size of 10 nm because of the improved oxidation resistance imparted by Ge doping.

Multilayer Epitaxial Heterostructures with Multi-Component III-V:Fe Magnetic Semiconductors.

Three-layer structures based on various multi-component films of III-V semiconductors heavily doped with Fe were grown using the pulsed laser sputtering of InSb, GaSb, InAs, GaAs and Fe solid targets. The structures comprising these InAsSb:Fe, InGaSb:Fe and InSb:Fe layers with Fe concentrations up to 24 at. % and separated by GaAs spacers were deposited on (001) i-GaAs substrates at 200 °C. Transmission electron microscopy showed that the structures have a rather high crystalline quality and do not contain secondary-phase inclusions. X-ray photoelectron spectroscopy investigations revealed a significant diffusion of Ga atoms from the GaAs regions into the InAsSb:Fe layers, which has led to the formation of an InGaAsSb:Fe compound with a Ga content up to 20 at. %. It has been found that the ferromagnetic properties of the InAsSb:Fe magnetic semiconductor improve with an increasing Sb:As ratio. It has been concluded that the indirect ferromagnetic exchange interaction between Fe atoms occurs predominantly via Sb atoms.

Influence of carbon target power on the tribological and electrochemical properties of NbMoSiC composite films in seawater

Because the wear and corrosion of marine engineering equipment will cause huge economic losses to enterprises every year, thus it is necessary to develop advanced protective films to ensure the normal operation of marine equipment. Here NbMoSiC composite films are deposited using DC magnetron sputtering in an argon atmosphere through varying the carbon target sputtering power, and their microstructure and mechanical properties are investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS)，Raman spectroscopy and dynamic ultra-micro hardness tester, respectively. The tribological properties of the films in air and artificial seawater are determined by a reciprocating ball-on-disc tester, while the electrochemical properties of the films in seawater were evaluated by an electrochemical workstation. The results demonstrate that the presence of Nb2C, MoSi2, free silicon, and amorphous carbon (a-C) in the NbMoSiC composite films. Particularly, Sample C250, featuring a carbon content of 35.02 at.%, exhibits higher hardness, elastic modulus, excellent wear resistance, and superior corrosion resistance. However, a further increase in carbon target sputtering power leads to escalated surface roughness and microchannels, ultimately resulting in reduced wear and corrosion performance. Electrochemical analysis reveal that the strong synergistic effect of amorphous carbon as well as the metal oxide phase formed on the surface significantly enhanced the corrosion resistance of the film in artificial seawater with a corrosion current density as low as 1.8 × 10−8 A/cm2.

The Role of Hydrogen Incorporation into Amorphous Carbon Films in the Change of the Secondary Electron Yield.

Over the last few years, there has been increasing interest in the use of amorphous carbon thin films with low secondary electron yield (SEY) to mitigate electron multipacting in particle accelerators and RF devices. Previous works found that the SEY increases with the amount of incorporated hydrogen and correlates with the Tauc gap. In this work, we analyse films produced by magnetron sputtering with different contents of hydrogen and deuterium incorporated via the target poisoning and sputtering of CxDy molecules. XPS was implemented to estimate the phase composition of the films. The maximal SEY was found to decrease linearly with the fraction of the graphitic phase in the films. These results are supported by Raman scattering and UPS measurements. The graphitic phase decreases almost linearly for hydrogen and deuterium concentrations between 12% and 46% (at.), but abruptly decreases when the concentration reaches 53%. This vanishing of the graphitic phase is accompanied by a strong increase of SEY and the Tauc gap. These results suggest that the SEY is not dictated directly by the concentration of H/D, but by the fraction of the graphitic phase in the film. The results are supported by an original model used to calculate the SEY of films consisting of a mixture of graphitic and polymeric phases.

Magnetic, magnetoresistive and structural properties of Cox(CoO)100-x thin film composites

The structural, magnetic, and magnetoresistive properties of Cox(CoO)100-x thin film composites synthesized by ion-beam sputtering of a composite target in an argon and mixed atmosphere (argon + oxygen) has been studied. The experimentally determined percolation threshold was significantly lower than that for most of the studied previously nanocomposites: ∼ 12.2 at % Co and ∼8.3 at % Co for films fabricated in inert and mixed atmosphere, respectively. This is explained by the special morphology of the films when small metallic Co nanoparticles are located on the surface of larger CoO particles. A negative tunnel-type magnetoresistance reaching 2.4% in 9 kOe field at room temperature was found for composites with close to the percolation threshold Co content. The magnetoresistance is proportional to the square of magnetization and is characterized by hysteresis, which correlates well with magnetic hysteresis. Magnetic hysteresis with a coercivity of the order of 700 Oe is observed for dielectric compositions up to 4 at. % Co. A possible reason for this behavior, along with the special morphology, is the appearance of thin layers of antiferromagnetic oxide at the interface between Co nanoparticles and CoO particles, which causes a significant increase in magnetic anisotropy.

Ohmic Contact to n-GaN Using RT-Sputtered GaN:O.

One of the key issues in GaN-based devices is the resistivity and technology of ohmic contacts to n-type GaN. This work presents, for the first time, effective intentional oxygen doping of sputtered GaN films to obtain highly conductive n+-GaN:O films. We have developed a novel and simple method to obtain these films. The method is based on the room temperature magnetron sputtering of a single crystal bulk GaN target doped with oxygen. The n+-GaN:O films exhibit a polycrystalline structure with a crack-free surface and a free electron concentration of 7.4 × 1018 cm3. Ohmic contact to GaN:Si with n+-GaN:O sub-contact layer achieves specific contact resistance of the order of 10-5 Ωcm2 after thermal treatment. The obtained results are very promising for the development of the technology of a whole new class of ohmic contacts to n-GaN.

Band-gap engineering of zirconia by nitrogen doping in reactive HiPIMS: a step forward in developing innovative technologies for photocatalysts synthesis.

In the global context of climate change and carbon neutrality, this work proposes a strategy to improve the light absorption of photocatalytic water-splitting materials into the visible spectrum by anion doping. In this framework, reactive high power impulse magnetron sputtering (HiPIMS) of a pure Zr target in Ar/N2/O2 gas mixture was used for the deposition of crystalline zirconium oxynitride (ZrO2-xNx) thin films with variable nitrogen doping concentration and energy band-gap. The nitrogen content into these films was controlled by the discharge pulsing frequency, which controls the target surface poisoning and peak discharge current. The role of the nitrogen doping on the optical, structural, and photocatalytic properties of ZrO2-xNx films was investigated. UV-Vis-NIR spectroscopy was employed to investigate the optical properties and to assess the energy band-gap. Surface chemical analysis was performed using X-ray photoelectron spectroscopy, while structural analysis was carried out by X-ray diffraction. The increase in the pulse repetition frequency determined a build-up in the nitrogen content of the deposited ZrO2-xNx thin films from ∼10 to ∼25at.%. This leads to a narrowing of the optical band-gap energy from 3.43 to 2.20eV and endorses efficient absorption of visible light. Owing to its narrow bandgap, ZrO2-xNx thin films obtained by reactive HiPIMS can be used as visible light-driven photocatalyst. For the selected processing conditions (pulsing configuration and gas composition), it was found that reactive HiPIMS can suppress the hysteresis effect for a wide range of frequencies, leading to a stable deposition process with a smooth transition from compound to metal-sputtering mode.

Enhanced mechanical properties and in vitro biocompatibility of TiMOVWCr high-entropy alloy synthesized by magnetron sputtering

This study proposes the synthesis of a high-entropy alloy (HEA) composed of TiMoVWCr and a new synthesis route specialized for high-entropy alloys (HEAs) using radio-frequency (RF) magnetron sputtering. The development of HEAs with diversification for various elements is paramount for bridging some limitations in the usage of materials in harsh environments. In developing HEA-preparation techniques, the emergence of a novel sputtering target system is promising for preparing a wide range of HEAs. Thus, a reproducible single target sputtering system is proposed for HEAs and is evaluated systematically. This new target-preparation technique aids in tailoring the elemental compositions to optimize the alloy for important mechanical and biomedical applications, e.g., titanium implants. Films are analyzed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy, and field emission scanning electron microscopy cross-sectional thickness. XRD and valence electron concentration (VEC) data showed a body-centered cubic structure with a major peak orientation of (110). Additionally, this alloy exhibited a very high hardness (29.2 GPa (±1.5)), elastic modulus (321 ± 8.9 GPa), smooth surface, and good cell viability compared to CP-Ti. The remarkably high hardness and elastic modulus are compared with the literature. Further, the crystalline phase is obtained at room temperature (RT) without undergoing post-treatment.

Low-cost fabrication of single chalcogenide CuInGaSe2 sputter target and its thin films for solar cell applications

Low-cost fabrication of single chalcogenide CuInGaSe2 sputter target and its thin films for solar cell applications

Determining the Annealing Temperature Dependency of Wetting and Mechanical Features on Fe3Si Films

The impact of thermal annealing under temperature alteration on the wetting and mechanical attributes of Fe3Si films built through facing target sputtering (FTS) is an essential topic for study in order to identify their characteristics under varying temperatures. Consequently, we introduced a thermal annealing process in a vacuum for two hours under varying temperatures of 300, 600, and 900 °C to our Fe3Si films created via FTS. The primary purpose of this current research is to examine the effect of the thermal annealing technique under temperature alteration on the wetting and mechanical traits of Fe3Si films. In this research, Fe3Si films were built onto the Si wafer by FTS and divided for use in thermal annealing under temperature alteration. The structural, morphological, wetting, and mechanical traits of the Fe3Si films under thermal annealing are provided in the present work. Based on our information, this work represents an original study on the change in wetting and mechanical traits of Fe3Si films through thermal annealing under temperature alteration.

Design and Development of High-Entropy Alloys with a Tailored Composition and Phase Structure Based on Thermodynamic Parameters and Film Thickness Using a Novel Combinatorial Target.

This study presents a novel synthesis route for high-entropy alloys (HEAs) and high-entropy metallic glass (HEMG) using radio frequency (RF) magnetron sputtering and controlling the HEA phase selection according to atomic size difference (δ) and film thickness. The preparation of HEAs using sputtering requires either multitargets or the preparation of a target containing at least five distinct elements. In developing HEA-preparation techniques, the emergence of a novel sputtering target system is promising to prepare a wide range of HEAs. A new HEA-preparation technique is developed to avoid multitargets and configure the target elements with the required components in a single target system. Because of a customizable target facility, initially, a TiZrNbMoTaCr target emerged with an amorphous phase owing to a high δ value of 7.6, which was followed by a solid solution (SS) by lowering the δ value to 5 (≤6.6). Thus, this system was tested for the first time to prepare TiZrNbMoTa HEA and TiZrNbMoTa HEMG via RF magnetron sputtering. Both films were analyzed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy, field emission scanning electron microscopy cross-sectional thickness, and atomic force microscopy (AFM). Furthermore, HEMG showed higher hardness 10.3 (±0.17) GPa, modulus 186 (±7) GPa, elastic deformation (0.055) and plastic deformation (0.032 GPa), smooth surface, lower corrosion current density (Icorr), and robust cell viability compared to CP-Ti and HEA. XRD analysis of the film showed SS with a body-centered cubic (BCC) structure with (110) as the preferred orientation. The valence electron concentration [VEC = 4.8 (<6.87)] also confirmed the BCC structure. Furthermore, the morphology of the thin film was analyzed through AFM, revealing a smooth surface for HEMG. Inclusively, the concept of configurational entropy (ΔSmix) is applied and the crystalline phase is achieved at room temperature, optimizing the processing by avoiding further furnace usage.

Effect of grain boundary scattering on carrier mobility and thermoelectric properties of tellurium incorporated copper iodide thin films

Copper iodide (CuI) is a promising p-type transparent semiconductor with many potential applications in range of fields such as transistors, optoelectronics, solar cells, thermal sensors, and energy harvesting. We report compositional, structural, optical, electrical, and thermoelectric properties of optically transparent tellurium (Te) incorporated CuI films, (CuI)1-xTex where x=0–0.09, prepared by ion beam sputtering. The films are composed of γ-CuI with the presence of elemental tellurium clusters in films prepared with high Te concentration sputtering targets. The carrier mobility decreased from 6.9 ± 0.9 cm2V-1s-1 to 0.7 ± 0.1 cm2V-1s-1, and the electrical conductivity from 84.22 ± 8.45 Scm-1 to 3.97 ± 0.40 Scm-1 for the CuI and (CuI)0.91Te0.09 films, respectively, attributed to a transition from polar optical phonon to grain boundary scattering. The change in the mobility-limiting scattering mechanism decreased the power factor from 454 ± 57 μWm-1K-2 for the CuI film to 34 ± 4 μWm-1K-2 for the (CuI)0.91Te0.09 film. Our study shows that modulating the scattering mechanism in transparent thermoelectric materials is a powerful method to tune their thermoelectric properties.