Search Results (65)

Thin amorphous oxide films (a-SiO₂, a-Al₂O₃, a-MgO) were prepared by magnetron sputtering deposition. Their response to high-energy heavy ion beams (23 MeV I, 18 MeV Cu, 2.5 MeV Cu) and gamma-ray (1.25 MeV) irradiation was studied by elastic recoil detection analysis and infrared spectroscopy. It was established that their high radiation hardness is due to a high level of disorder, already present in as-prepared samples, so the high-energy heavy ion irradiation cannot change their structure much. In the case of a-SiO₂, this resulted in a completely different response to high-energy heavy ion irradiation found previously in thermally grown a-SiO₂. In the case of a-MgO, only gamma-ray irradiation was found to induce significant changes. Full article

This study developed a neutron-beam-focusing supermirror for grazing-incidence small-angle neutron scattering (GISANS) measurements. We adopted point-to-point beam focusing based on an ellipse whose two foci correspond to a virtual point source and a spot on the detector surface. The focusing supermirror was fabricated by depositing NiC/Ti supermirror film with ion-beam sputtering on a precise elliptic surface of fused quartz figured using the elastic emission machining technique. Neutron measurements at the pulsed neutron reflectometer BL17 of the MLF, J-PARC, successfully demonstrated that the focusing supermirror enhances the beam intensity twentyfold compared with an optimally collimated beam, achieving a signal-to-background ratio of the focal spot as high as 500. The mirror can be readily installed and used at BL17 for time-of-flight GISANS measurements. Full article

Periodically modulated optical coatings, fabricated by depositing conformal films on modulated substrates, offer unique capabilities for spectral and spatial filtering of light. However, conventional deposition methods often do not achieve required replication and conformality on submicron-size structured surfaces. In this paper, we compare various thin film deposition techniques, including electron beam evaporation, atomic layer deposition, and ion beam sputtering, to evaluate their ability to control multilayer coating growth on periodically modulated substrates. Our study demonstrates that both single-layer and multilayer coatings produced by ion beam sputtering effectively replicate the initial geometry of structured surfaces, thereby enhancing optical performance. Full article

The knowledge of Li diffusivities in electrode materials of Li-ion batteries (LIBs) is essential for a fundamental understanding of charging/discharging times, maximum capacities, stress formation and possible side reactions. The literature indicates that Li diffusion in the cathode material Li(Ni,Mn,Co)O₂ strongly increases during electrochemical delithiation. Such an increased Li diffusivity will be advantageous for performance if it is present already in the initial state after synthesis. In order to understand the influence of a varying initial Li content on Li diffusion, we performed Li tracer diffusion experiments on Li_xCoO₂ (LCO) and Li_xNi_1/3Mn_1/3Co_1/3O₂ (NMC, x = 1, 0.9, 0.65) cathode materials. The measurements were performed on polycrystalline sintered bulk materials, free of additives and binders, in order to study the intrinsic properties. The variation of Li content was achieved using reactive solid-state synthesis using pressed Li₂CO₃, NiO, Co₃O₄ and/or MnO₂ powders and high temperature sintering at 800 °C. XRD analyses showed that the resultant bulk samples exhibit the layered LCO or NMC phases with a low amount of cation intermixing. Moreover, the presence of additional NiO and Co₃O₄ phases was detected in NMC with a pronounced nominal Li deficiency of x = 0.65. As a tracer source, a ⁶Li tracer layer with the same chemical composition was deposited using ion beam sputtering. Secondary ion mass spectrometry in depth profile mode was used for isotopic analysis. The diffusivities followed the Arrhenius law with an activation enthalpy of about 0.8 eV and were nearly identical within error for all samples investigated in the temperature range up to 500 °C. For a diffusion mechanism based on structural Li vacancies, the results indicated that varying the Li content does not result in a change in the vacancy concentration. Consequently, the design and use of a cathode initially made of a Li-deficient material will not improve the kinetics of battery performance. The possible reasons for this unexpected result are discussed. Full article

Mechanically flexible substrates are increasingly utilized in electronics and advanced energy technologies like solar cells and high-temperature superconducting coated conductors (HTS-CCs). These substrates offer advantages, such as large surface areas and reduced manufacturing costs through reel-to-reel processing, but often lack the surface smoothness needed for optimal performance. For HTS-CCs, specific orientation and high crystalline quality are essential, requiring buffer layers to prepare the amorphous substrate for superconductor deposition. Techniques, such as mechanical polishing, electropolishing, and chemical-mechanical polishing, can help achieve an optimally levelled surface suitable for the subsequent steps of sputtering and ion-beam-assisted deposition (IBAD) necessary for texturing. This review examines Solution Deposition Planarization (SDP) as a cost-effective alternative to traditional electro-mechanical polishing for HTS coated conductors. SDP achieves surface roughness levels below 1 nm through multiple oxide layer coatings, offering reduced production costs. Comparative studies demonstrate planarization efficiencies of up to 20%. Ongoing research aims to enhance SDP’s efficiency for industrial applications in CC production. Full article

Nanoparticles are essential for energy storage, catalysis, and medical applications, emphasizing their accurate chemical characterization. However, atom probe tomography (APT) of nanoparticles sandwiched at the interface between an encapsulating film and a substrate poses difficulties. Poor adhesion at the film-substrate interface can cause specimen fracture during APT, while impurities may introduce additional peaks in the mass spectra. We demonstrate preparing APT specimens with strong adhesion between nanoparticles and film/substrate matrices for successful analysis. Copper nanoparticles were encapsulated at the interface between nickel film and cobalt substrate using electrodeposition. Cobalt and nickel were chosen to match their evaporation fields with copper, minimizing peak overlaps and aiding nanoparticle localization. Copper nanoparticles were deposited via magnetron sputter inert gas condensation with varying deposition times to yield suitable surface coverages, followed by encapsulation with the nickel film. In-plane and cross-plane APT specimens were prepared by femtosecond laser ablation and focused ion beam milling. Longer deposition times resulted in agglomerated nanoparticles as well as pores and voids, causing poor adhesion and specimen failure. In contrast, shorter deposition times provided sufficient surface coverage, ensuring strong adhesion and reducing void formation. This study emphasizes controlled surface coverage for reliable APT analysis, offering insights into nanoparticle chemistry. Full article

Fabrication aspects of PdO thin films and coatings are reviewed here. The work provides and organizes the up-to-date information on the methods to obtain the films. In recent years, the interest in Pd oxide for different applications has increased. Since Pd can be converted into PdO, it is instructive to pay attention to the preparation of the pure and the alloyed Pd films, heterostructures, and nanoparticles synthesized on different substrates. The development of PdO films is presented from the early reports on coatings’ formation by oxidation of Pd foils and wires to present technologies. Modern synthesis/growth routes are gathered into chemical and physical categories. Chemical methods include hydrothermal, electrochemical, electroless deposition, and coating methods, such as impregnation, precipitation, screen printing, ink jet printing, spin or dip coating, chemical vapor deposition (CVD), and atomic layer deposition (ALD), while the physical ones include sputtering and cathodic arc deposition, laser ablation, ion or electron beam-induced deposition, evaporation, and supersonic cluster beam deposition. Analysis of publications indicates that many as-deposited Pd or Pd-oxide films are granular, with a high variety of morphologies and properties targeting very different applications, and they are grown on different substrates. We note that a comparative assessment of the challenges and quality among different films for a specific application is generally missing and, in some cases, it is difficult to make a distinction between a film and a randomly oriented, powder-like (granular), thin compact material. Textured or epitaxial films of Pd or PdO are rare and, if orientation is observed, in most cases, it is obtained accidentally. Some practical details and challenges of Pd oxidation toward PdO and some specific issues concerning application of films are also presented. Full article

Amorphous carbon (a-C) has promising potential for temperature sensing due to its outstanding properties. In this work, an a-C thin film temperature sensor integrated with the MEMS silicon accelerometer was proposed, and a-C film was deposited on the fixed frame of the accelerometer chip. The a-C film was deposited by DC magnetron sputtering and linear ion beam, respectively. The nanostructures of two types of films were observed by SEM and TEM. The cluster size of sp² was analyzed by Raman, and the content of sp² and sp³ of the carbon film was analyzed by XPS. It showed that the DC-sputtered amorphous carbon film, which had a higher sp² content, had better temperature-sensitive properties. Then, an integrated sensor chip was designed, and the structure of the accelerometer was simulated and optimized to determine the final sizes. The temperature sensor module had a sensitivity of 1.62 mV/°C at the input voltage of 5 V with a linearity of 0.9958 in the temperature range of 20~150 °C. The sensitivity of the sensor is slightly higher than that of traditional metal film temperature sensors. The accelerometer module had a sensitivity of 1.4 mV/g/5 V, a nonlinearity of 0.38%, a repeatability of 1.56%, a total thermomechanical noise of 509 μg over the range of 1 to 20 Hz, and an average thermomechanical noise density of 116 µg/√Hz, which is smaller than the input acceleration amplitude for testing sensitivity. Under different temperatures, the performance of the accelerometer was tested. This research provided significant insights into the convenient procedure to develop a high-performance, economical temperature–accelerometer-integrated MEMS sensor. Full article

The surfaces of ceramic products are replete with numerous defects, such as those that appear during the diamond grinding of sintered SiAlON ceramics. The defective surface layer is the reason for the low effectiveness of TiZrN coatings under abrasive and fretting wear. An obvious solution is the removal of an up to 4-µm-thick surface layer containing the defects. It was proposed in the present study to etch the layer with fast argon atoms. At the atom energy of 5 keV and a 0.5 mA/cm² current density, the ions were converted into fast atoms and the sputtering rate for the SiAlON samples reached 20 μm/h. No defects were observed in the microstructures of coatings deposited after beam treatment for half an hour. The treatment reduced the volumetric abrasive wear by five times. The fretting wear was reduced by three to four times. Full article

Wafer-scale blue micro-light-emitting diode (micro-LED) arrays were fabricated with a pixel size of 12 μm, a pixel pitch of 15 μm, and a pixel density of 1692 pixels per inch, achieved by optimizing the properties of e-beam-deposited and sputter-deposited indium tin oxide (ITO). Although the sputter-deposited ITO (S-ITO) films exhibited a densely packed morphology and lower resistivity compared to the e-beam-deposited ITO (E-ITO) films, the forward voltage (V_F) values of a micro-LED with the S-ITO films were higher than those with the E-ITO films. The V_F values for a single pixel and for four pixels with E-ITO films were 2.82 V and 2.83 V, respectively, while the corresponding values for S-ITO films were 3.50 V and 3.52 V. This was attributed to ion bombardment damage and nitrogen vacancies in the p-GaN layer. Surprisingly, the V_F variations of a single pixel and of four pixels with the optimized E-ITO spreading layer from five different regions were only 0.09 V and 0.10 V, respectively. This extremely uniform V_F variation is suitable for creating micro-LED displays to be used in AR and VR applications, circumventing the bottleneck in the development of long-lifespan and high-brightness organic LED devices for industrial mass production. Full article

Vertical Schottky barrier diodes based on an ion beam sputter (IBS)-deposited β-Ga₂O₃ film on a single-crystalline ($\overline{2}$01) unintentionally doped (UID) β-Ga₂O₃ with a Ni contact were developed. To form ohmic Ti/Ni contacts, the IBS-Ga₂O₃/UID β-Ga₂O₃ structures were wet-etched, and an indium tin oxide (ITO) intermediate semiconductor layer (ISL) was deposited on the opposite surface of the UID β-Ga₂O₃. The IBS-deposited Ga₂O₃ layer was polycrystalline and semi-insulating. Low leakage currents, rectification ratios of 3.9 × 10⁸ arb. un. and 3.4 × 10⁶ arb. un., ideality factors of 1.43 and 1.24, Schottky barrier heights of 1.80 eV and 1.67 eV as well as breakdown voltages of 134 V and 180 V were achieved for diodes without and with ITO-ISL, respectively. The surface area of the IBS-Ga₂O₃ film acted as a thin dielectric layer and, together with the preliminary wet etching, provided low leakage currents and relatively high Schottky barrier heights. Diodes with a Schottky barrier based on a Ni/IBS-deposited Ga₂O₃ film contact were demonstrated for the first time. Full article

Copper-nitride (Cu${}_3$N) semiconductor material is attracting much attention as a potential, next-generation thin-film solar light absorber in solar cells. In this communication, polycrystalline covalent Cu${}_3$N thin films were prepared using reactive-RF-magnetron-sputtering deposition, at room temperature, onto glass and silicon substrates. The very-broadband optical properties of the Cu${}_3$N thin film layers were studied by UV-MIR (0.2–40 $\mathsf{\mu }$m) ellipsometry and optical transmission, to be able to achieve the goal of a low-cost absorber material to replace the conventional silicon. The reactive-RF-sputtered Cu${}_3$N films were also investigated by focused ion beam scanning electron microscopy and both FTIR and Raman spectroscopies. The less dense layer was found to have a value of the static refractive index of 2.304, and the denser film had a value of 2.496. The iso-absorption gap, $E_{04}$, varied between approximately 1.3 and 1.8 eV and could be considered suitable as a solar light absorber. Full article

In the present study, (Cr,Al)N nanolayer coatings with different Al/Cr atomic ratios were deposited by magnetron sputtering on different substrate materials (H11 and D2 tool steel, alumina). To prepare the (Cr,Al)N coatings with different Al/Cr atomic ratios in the same batch, we used two targets composed of two triangle-like segments together with two standard Al and Cr targets. This approach enabled us to study the evolution of structural and mechanical properties in dependence on composition. The elemental composition of the coatings was determined by energy-dispersive X-ray analysis (EDS). The phase composition of the (Cr,Al)N coatings was determined utilizing X-ray diffraction (XRD), while scanning electron microscopy (SEM) was employed to assess their morphology and microstructure. The coating surface topography was analyzed by atomic force microscopy (AFM). In order to evaluate the effect of the Al/Cr atomic ratio on the oxidation behavior, the (Cr,Al)N coatings were oxidized in ambient atmospheres at temperatures between 700 and 850 °C and subsequently analyzed by means of cross-sectional SEM and transmission electron microscopy (TEM). The oxidation rate, determined by weight gain over time, was utilized to quantify the oxidation process. The oxidation tests showed that the Al-rich (Cr,Al)N nanolayer coatings exhibit a considerably better oxidation resistance than the Cr-rich ones. We found that the oxide scale formed on the Al-rich coating is composed of double layers: a Cr-oxide top layer and an inner (Cr,Al) mixed oxide layer. In contrast, the oxide scale of the Cr-rich coating mainly consists of the Cr₂O₃ layer. In particular, we focused on the oxidation process occurring at the locations of growth defects. We noticed that the first oxidation products on the coated substrate occurred at a temperature that was much lower than the temperature for the (Cr,Al)N coating oxidation initiation. These products (iron oxides) formed only at the sites of those growth defects that extended through the entire coating thickness. Full article

Numerous technological advancements in the 21st century depend on the creation of novel materials possessing enhanced properties; there is a growing reliance on materials that can be optimized to serve multiple functions. To efficiently save time and meet the requirements of diverse applications, high-throughput and combinatorial approaches are increasingly employed to explore and design superior materials. Among them, gradient thin-film deposition is one of the most mature and widely used technologies for high-throughput preparation of material libraries. This review summarizes recent progress in gradient thin-film deposition fabricated by magnetron sputtering, multi-arc ion plating, e-beam evaporation, additive manufacturing, and chemical bath deposition, providing readers with a fundamental understanding of this research field. First, high-throughput synthesis methods for gradient thin films are emphasized. Subsequently, we present the characteristics of combinatorial films, including microstructure, oxidation, corrosion tests, and mechanical properties. Next, the screening methods employed for evaluating these properties are discussed. Furthermore, we delve into the limitations of high-throughput preparation and characterization techniques for combinatorial films. Finally, we provide a summary and offer our perspectives. Full article

Ion beam-assisted deposition (IBAD) has been proposed as a promising texturing technology that uses the film epitaxy method to obtain biaxial texture on a non-textured metal or compound substrate. Magnesium oxide (MgO) is the most well explored texturing material. In order to obtain the optimal biaxial texture, the actual thickness of the IBAD-MgO film must be controlled within 12nm. Due to the bombardment of ion beams, IBAD-MgO has large lattice deformation, poor texture, and many defects in the films. In this work, the solution deposition planarization (SDP) method was used to deposit oxide amorphous Y₂O₃ films on the surface of Hastelloy C276 tapes instead of the electrochemical polishing, sputtering-Al₂O₃ and sputtering-Y₂O₃ in the commercialized buffer layer. An additional homogeneous epitaxy MgO (epi-MgO) layer, which was used to improve the biaxial texture in the IBAD-MgO layer, was deposited on the IBAD-MgO layer by electron-beam evaporation. The effects of growth temperature, film thickness, deposition rate, and oxygen pressure on the texture and morphology of the epi-MgO film were systematically studied. The best full width at half maximum (FWHM) values were 2.2° for the out-of-plane texture and 4.8° for the in-plane texture for epi-MgO films, respectively. Subsequently, the LaMnO₃ cap layer and YBa₂Cu₃O₇-x (YBCO) functional layer were deposited on the epi-MgO layer to test the quality of the MgO layer. Finally, the critical current density of the YBCO films was 6 MA/cm² (77 K, 500 nm, self-field), indicating that this research provides a high-quality MgO substrate for the YBCO layer. Full article