Search Results (122)

This study employs reactive magnetron sputtering technology to fabricate TiN/Y-HfO₂/TiN multilayer thin film devices using titanium targets and yttrium-doped high-purity hafnium targets. A systematic investigation was conducted to explore the influence of hafnium-based thin film thickness on the structural and electrical properties of TiN/Y-HfO₂/TiN thin film devices. Radio frequency magnetron sputtering was utilized to deposit Y-HfO₂ films of varying thicknesses on TiN electrodes by controlling deposition time, with a yttrium doping concentration of 8.24 mol.%. The surface morphology and crystal structure of the thin films were characterized using atomic force microscopy (AFM), Raman spectroscopy, X-ray diffraction (XRD). Results indicate that as film thickness increases, surface roughness and Raman peak intensity increase correspondingly, with the tetragonal phase (t) characteristic peak being most prominent at 65 nm. DC magnetron sputtering was employed to deposit TiN top electrodes, resulting in TiN/Y-HfO₂/TiN thin film devices. Following rapid thermal annealing at 700 °C, electrical properties were evaluated using a ferroelectric tester. Leakage current density exhibited a decreasing trend with increasing film thickness, while the maximum polarization intensity gradually increased, reaching a maximum of 11.5 μC/cm² at 120 nm. Full article

The response of titanium (Ti) thin films is closely related to their microstructure, which is extremely sensitive to the selected deposition parameters and geometrical configurations. The present study investigates the impact of geometrical factors on the growth of Ti thin films, focusing on how variations in growth geometry influence film microstructure, surface morphology, and corrosion resistance. Three Ti thin films were prepared using Glancing Angle Deposition (GLAD) in a custom-built DC reactive magnetron sputtering system. For the first sample, the target was positioned perpendicular to the substrate surface (α = 0°); for the second and third samples, the substrate holder was positioned at an angle of 85° regarding the target direction (α = 85°), incorporating a 180° azimuthal rotation for the last (to obtain a zigzag-like deposition). The thickness and morphological features of the thin films were investigated by SEM, while the surface morphology, specifically roughness, and crystallinity of the thin films were assessed by AFM and XRD, respectively. Continuous and alternating current techniques were used for electrochemical characterization of behavior in simulated body fluid. The obtained results show a clear tendency to an improvement in anticorrosion performances varying the nanoarchitecture of the films in comparison to the conventional-grown sample, with the inclined sample presenting a slight enhancement in corrosion resistance and the zigzag-grown sample having the best corrosion resistance properties of the three. Full article

We report about the effect of nitrogen and carbon concentration on the superconducting transition temperature T_C of (NbMoTaW)₁C_xN_y carbonitride films deposited using reactive DC magnetron sputtering. By measuring the temperature dependence of electrical resistance and magnetization of these carbonitrides, with 0.20 ≤ x ≤ 1.17 and 0 ≤ y ≤ 0.73, we observe a T_C enhancement that occurs especially at high (x ≥ 0.76) carbon concentrations, with the largest T_C = 9.6 K observed in the over-doped fcc crystal structure with x = 1.17 and y = 0.41. The reason why the largest T_C appears at high C concentrations is probably related to the lower atomic mass of carbon compared to nitrogen and to the increase in the electron–phonon interaction due to different bonding of carbon (compared to nitrogen) to the Nb-Mo-Ta-W metallic sublattice. However, for concentrations where y > 0.71 and x + y > 1.58, two structural phases begin to form. Additionally, the proximity to structural instability may play a role in the observed B_C2 enhancement. Further measurements in a magnetic field show that the upper critical fields B_C2 of (NbMoTaW)₁C_xN_y carbonitrides provide B_C2/B_C2 < 2 T/K, which falls within the weak-coupling pair breaking limit. Full article

Chromium–aluminum nitride (CrAlN) coatings were deposited on polished H13 tool steel substrates using direct current (DC) magnetron sputtering. The Cr/Al composition in the target was varied by inserting either four or eight chromium (Cr) plugs into cavities machined into an aluminum (Al) plate target. Nitrogen was introduced as a reactive gas to facilitate the formation of the nitride phase. Coatings were deposited at substrate bias voltages of −30 V, −50 V, and −60 V to study the combined effects of composition and ion energy on coating properties. Compositional analysis of coatings deposited at a −50 V bias revealed Cr/Al ratios of approximately 0.8 and 1.7 for the 4- and 8-plug configurations, respectively. This increase in the Cr/Al ratio led to a 2.6-fold improvement in coating hardness. Coatings produced using the eight-Cr-plug target exhibited a nearly linear increase in hardness with increasing substrate bias voltage. Cross-sectional scanning electron microscopy revealed a uniform bilayer structure consisting of an approximately 0.5 µm metal interlayer beneath a 2–3 µm CrAlN coating. Surface morphology analysis indicated the presence of coarse microdroplets in coatings with the lower Cr/Al ratio. These microdroplets were significantly suppressed in coatings with higher Cr/Al content, especially at increased bias voltages. This suppression is likely due to enhanced ion bombardment associated with the increased Cr content, attributed to Cr’s relatively higher atomic mass compared to Al. Coatings with lower hardness exhibited greater scratch resistance, likely due to the influence of residual compressive stresses. The findings highlight the critical role of both Cr/Al content and substrate bias in tailoring the tribo-mechanical performance of PVD CrAlN coatings for wear-resistant applications. Full article

This study examines the effect of oxygen concentration and sputtering power on the surface morphology of TiO₂ thin films deposited by DC reactive magnetron sputtering. Surface roughness parameters were obtained using MountainsMap^® software(10.2) from SEM images, while fractal dimensions and texture descriptors were extracted via Python-based image processing. Fractal dimension was calculated using the box-counting method applied to binarized images with multiple threshold levels, and texture analysis employed Gray-Level Co-occurrence Matrix (GLCM) statistics to capture local anisotropies and spatial heterogeneity. Four samples were analyzed, previously prepared with oxygen concentrations of 50% and 75%, and sputtering powers of 500 W and 1000 W. The results have shown that films deposited at higher oxygen levels and sputtering powers exhibited increased roughness, higher fractal dimensions, and stronger GLCM contrast, indicating more complex and heterogeneous surface structures. Conversely, films produced at lower oxygen and power settings showed smoother, more isotropic surfaces with lower complexity. This integrated analysis framework links deposition parameters with morphological characteristics, enhancing the understanding of surface evolution and enabling better control of TiO₂ thin film properties. Full article

In recent years, significant attention has been directed toward the development of coating materials capable of tailoring surface properties for various functional applications. Transition metal nitrides, in particular, have garnered interest due to their superior physical and chemical properties, including high hardness, excellent wear resistance, and strong corrosion resistance. In this study, a fabrication process for CrN-based thin films was developed by combining reactive direct current magnetron sputtering (dcMS) with post-deposition annealing in air. CrN coatings were deposited by reactive dcMS using different argon-nitrogen (Ar:N₂) gas ratios (4:1, 3:1, 2:1, and 1:1), followed by annealing at 550 °C for 1.5 h in ambient air. XRD and EDS analysis revealed that this treatment results in the formation of a composite phase comprising CrN and Cr₂O₃. The resulting coating exhibited favorable mechanical and tribological properties, including a maximum hardness of 12 GPa, a low wear coefficient of 0.254 and a specific wear rate of 7.05 × 10⁻⁶ mm³/N·m, making it a strong candidate for advanced protective coating applications. Full article

Memristors with resistive switching capabilities are vital for information storage and brain-inspired computing, making them a key focus in current research. This study demonstrates non-volatile analog resistive switching behavior in Al/TiO_x/TiN/Si(n⁺⁺)/Al memristive devices. Analog resistive switching offers gradual, controllable conductance changes, which are essential for mimicking brain-like synaptic behavior, unlike digital/abrupt switching. The amorphous titanium oxide (TiO_x) active layer was deposited using the pulsed-DC reactive magnetron sputtering technique. The impact of increasing the oxide thickness on the electrical performance of the memristors was investigated. Electrical characterizations revealed stable, forming-free analog resistive switching, achieving endurance beyond 300 DC cycles. The charge conduction mechanisms underlying the current–voltage (I–V) characteristics are analyzed in detail, revealing the presence of ohmic behavior, Schottky emission, and space-charge-limited conduction (SCLC). Experimental results indicate that increasing the TiO_x film thickness from 31 to 44 nm leads to a notable change in the current conduction mechanism. The results confirm that the memristors have good stability (>1500 s) and are capable of exhibiting excellent long-term potentiation (LTP) and long-term depression (LTD) properties. The analog switching driven by oxygen vacancy-induced barrier modulation in the TiO_x/TiN interface is explained in detail, supported by a proposed model. The remarkable switching characteristics exhibited by the TiO_x-based memristive devices make them highly suitable for artificial synapse applications in neuromorphic computing systems. Full article

This work investigates the impact of reset pulse width on multilevel conductance programming in Al₂O₃/TiO_x-based resistive random access memory. A 32 × 32 cross-point array of Ti (12 nm)/Pt (62 nm)/Al₂O₃ (3 nm)/TiO_x (32 nm)/Ti (14 nm)/Pt (60 nm) devices (2.5 µm × 2.5 µm active area) was fabricated via e-beam evaporation, atomic layer deposition, and reactive sputtering. Following an initial forming step and a stabilization phase of five DC reset–set cycles, devices were programmed using an incremental step pulse programming (ISPP) scheme. Reset pulses of fixed amplitude were applied with widths of 100 µs, 10 µs, 1 µs, and 100 ns, and the programming sequence was terminated when the read current at 0.2 V exceeded a 45 µA target. At a 100 µs reset pulse width, most cycles exhibited abrupt current jumps that exceeded the target current, whereas at a 100 ns width, the programmed current increased gradually in all cycles, enabling precise conductance tuning. Cycle-to-cycle variation decreased by more than 50% as the reset pulse width was reduced, indicating more uniform filament disruption and regrowth. These findings demonstrate that controlling reset pulse width offers a straightforward route to reliable, linear multilevel operation in Al₂O₃/TiO_x-based RRAM. Full article

The aim of this study was to produce a coating for protective glass glued to touch displays with high antibacterial effectiveness. This paper presents the structural, mechanical, optical, and antibacterial properties of a TiO₂:Ag–Pt coating prepared by dual reactive DC and RF magnetron sputtering. Characterization techniques used include XRD, TEM with EDS, SEM, AFM, nanoindentation for hardness and Young’s modulus, wettability tests, and optical property analysis. The coating exhibited columnar crystals with a width of 30–50 nm. Crystals of anatase, rutile, silver, and platinum with a size of up to 3 nm were identified. The coating deposited on glass had a concentration of 5.0 ± 0.2% at. Ag and 4.4 ± 0.1% at. Pt. The value of the optical band gap energy, corresponding to the direct transition, was 3.36 eV, while Urbach’s energy was in the order of 500 meV. The hydrophilic coating had a roughness RMS = 1.8 ± 0.2 nm, hardness HV = 6.8 ± 0.5 GPa, and Young’s modulus E = 116 ± 8 GPa. A unique combination of the phase composition of the TiO₂:Ag–Pt coating, metallic Ag and Pt nanoparticles in a ceramic matrix of anatase and rutile crystallites resulted a >90% reduction of Staphylococcus aureus bacteria. This antibacterial effect was attributed to the activation of the doped semiconductor under visible light via plasmon resonance of the Ag and Pt nanoparticles, as well as a light-independent antibacterial action due to Ag⁺ ion release. In contrast, commercial antibacterial coatings typically achieve only around 60% bacterial reduction. Full article

We report the photocatalytic (PC) response of titanium oxide (TiO_x) films grown by reactive DC magnetron sputtering under oblique-angle-deposition (OAD) and subjected to post-deposition flash-lamp-annealing (FLA). Under ballistic growth conditions, OAD yields TiO_x films with either compact or inclined columnar structure as the deposition incidence angle (α) with respect to the substrate normal varies from zero to grazing. On the one hand, films produced for α ≤ 45° display a compact and opaque structure comprising the formation of nanocrystalline cubic titanium monoxide (c-TiO) phase. On the other hand, films grown at larger α (≥60°) display tilted columns with amorphous structure, yielding highly porous films and an increased transparency for α > 75°. For TiO_x films grown at large α, FLA induces phase transformation to nanocrystalline anatase from the amorphous state. In contrast to as-grown samples, FLA samples display PC activity as assessed by bleaching of methyl orange dye. The best PC performance is attained for an intermediate situation (α = 60–75°) between compact and columnar structures. The obtained photoactivity is discussed in terms of the different microstructures obtained by OAD and posterior phase formation upon FLA. Full article

This paper investigates the influence of C₂H₂ flow rates on the optical properties, surface roughness, and residual stress of Ti/WC thin films deposited on glass substrates. A range of Ti/WC thin films with varying carbon contents were prepared using the reactive pulsed DC magnetron sputtering technique. The properties of the Ti/WC films can be tuned by adjusting the deposition parameters, among which the acetylene (C₂H₂) flow rate plays a key role in determining the thin film’s microstructure, optical properties, and stress behavior. The optical properties of the thin films were analyzed using UV-visible-NIR spectroscopy and Fourier transform infrared (FTIR) spectroscopy, the surface morphology was analyzed using microscopic interferometry, and the residual stress in the films was measured using a homemade Twyman–Green interferometer. The measurement results show that the average reflectance of Ti/WC films decreases with the increase in the C₂H₂ flow rate, and the measured value changes from 52.24% to 44.56% in the wavelength of 400–800 nm. The infrared reflectance of Ti/WC films in the wavelength of 2.5–25 μm is 81.8% for 10 sccm, 80.8% for 20 sccm, 77.2% for 30 sccm, and 73.6% for 40 sccm. The tensile stress of the Ti/WC films deposited on B270 substrates increases with the increase in the C₂H₂ flow rate, and the stress value changes from 0.361 GPa to 0.405 GPa. The surface roughness of Ti/WC films initially increases and then decreases slightly with the increase in the C₂H₂ flow rate. These results indicate that the C₂H₂ flow ratio significantly affects the reflectance in the visible and infrared bands, surface roughness, and residual stress of the Ti/WC films, which is of great significance for optimizing thin film performance to meet specific application requirements. Full article

In this study, four various titanium dioxide/cuprum oxide (TiO₂/Cu_xO) photovoltaic structures deposited on glass/indium tin oxide (ITO) substrates using the direct-current (DC) reactive magnetron sputtering technique were annealed in air. In our previous work, the deposition parameters for different buffer layer configurations were first optimized to enhance cell fabrication efficiency. In this paper, the effects of post-deposition annealing at 150 °C in air on the optical properties and I-V characteristics of the prepared structures were examined. As a result, significant changes in optical properties and a meaningful improvement in performance in comparison to unannealed cells were observed. Air annealing led to an increase in the reflection coefficient of the TiO₂ layer for three out of four structures. A similar increase in the reflection of the Cu_xO layer occurred after heating for two out of four structures. Transmission of the TiO₂/Cu_xO photovoltaic structures also increased after heating for three out of four samples. For two structures, changes in both transmission and reflection resulted in higher absorption. Moreover, annealing the as-deposited structures resulted in a maximum relative increase in open-circuit voltage (V_oc) by 294% and an increase in short-circuit current (I_sc) by 1200%. The presented article gives some in-depth analysis of these reported changes in character and origin. Full article

To address modern tribological challenges—reducing friction and wear to conserve resources while minimising environmental impact—cobalt-doped DLC (Co-DLC) coatings were developed. These nanometric multilayer coatings, designed to retain key properties such as hardness, reduced modulus, and substrate adhesion, were fabricated using non-reactive DC magnetron sputtering (DCMS). The multilayer structure was achieved by controlling the planetary substrate holder’s rotational speed. Characterisation of microscopic, chemical, structural, and mechanical properties was performed using techniques including FEI-SEM, EDS, XRD, TEM, Raman spectroscopy, scratch adhesion testing, and nanoindentation. Tribological performance was evaluated under boundary and fully flooded lubrication using PAO4 base oil and formulations with ashless, sulphur-free AW and EP additives. The coatings exhibited a granular surface morphology, columnar cross-sections, and amorphous structure. Increased dopant concentrations slightly enhanced graphitisation and significantly improved adhesion, though hardness and reduced modulus decreased. Tribological testing revealed superlubricity in several coating–oil combinations and significantly reduced wear rates with higher dopant levels and new additives. A phosphate ester additive without an amine group achieved the lowest COF values, while one with an amine group yielded minimal wear rates. These findings highlight the potential of Co-DLC coatings and tailored additives to minimise friction and wear effectively. Full article

Zirconium nitrides films were synthesized on Ti6Al4V substrates at a bias voltage of −50 V, −80 V, −110 V and −150 V by the direct current (DC) reactive magnetron sputtering technique. The as-deposited coatings were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The wear and corrosion resistance of the obtained ZrN coatings were evaluated to determine the possibility for their implementation in modern biomedical applications. It was found that the intensity of the diffraction peak of the Zr-N phase corresponding to the (1 1 1) crystallographic plane rose as the bias voltage increased, while the ZrN coatings’ thickness reduced from 1.21 µm to 250 nm. The ZrN films’ surface roughness rose up to 75 nm at −150 V. Wear tests showed an increase in the wear rate and wear intensity as the bias voltage increased. Corrosion studies of the ZrN coatings were carried out by three electrochemical methods: open circuit potential (OCP), cyclic voltammetry (polarization measurements) and electrochemical impedance spectroscopy (EIS). All electrochemical measurements confirmed that the highest protection to corrosion is the ZrN coating, which was deposited on the Ti6Al4V substrate at a bias voltage of −150 V. Full article

The literature analysis did not indicate any studies on fluorination tests of carbon nanocomposite coatings doped with transition metals in a form of nanocrystalline metal carbide in amorphous carbon matrix (nc-MeC/a-C). As a model coating to investigate the effect of fluorination in a tetrafluoromethane (CF₄) atmosphere, a nanocomposite carbon coating doped with chromium-forming nanocrystals of chromium carbides in a-C matrix (nc-CrC/a-C) produced by magnetron sputtering from graphite targets and using a Pulse-DC type medium frequency power supply was chosen. After the deposition of the gradient chromium carbonitride (CrCN) adhesive sublayer, the fluorination of the main coating was conducted in a reactive mode in an (Ar + CF₄) atmosphere at various CF₄ content. It was observed that the presence of CF₄ in the atmosphere resulted in a reduced amount of chromium carbides formed in favor of chromium fluorides. Thus far, this is an observation that seems unnoticed by the carbon coatings researchers. Fluorine was assumed to bond much more readily to carbon than to chromium, due to the stability of tetrafluoromethane (CF₄). The opposite seems to be true. The mechanical properties (nano-hardness and Young’s modulus) and tribological properties in the ‘pin-on-disc’ friction pair are presented, along with the analysis of bonds occurring between chromium, carbon, and fluorine by means of X-ray photoelectron spectroscopy (XPS). Full article