Nickel aluminium bronze (NAB) alloys are widely used in marine applications due to their inherent corrosion resistance, mechanical strength, and surface durability. However, the material might reveal microstructural defects such as coarse grain sizes and localized stress points associated with manufacturing, which significantly compromise its performance. These defects degrade performance under severe marine wear conditions, necessitating an effective surface barrier. Accordingly, surface modification was adopted as an effective strategy. Chromium nitride coatings were deposited by direct-current (DC) magnetron sputtering on NAB substrates to enhance their surface properties in this research work. X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Energy dispersive spectroscopy (EDS), and X-ray Photoelectron Spectroscopy (XPS) confirmed the crystalline formation of a Cr2N phase with a uniform and dense columnar microstructure. Mechanical properties improved significantly, as evidenced by nanoindentation results, with the coated NAB showing a hardness of 11.21 ± 0.57 GPa, although it has a much higher elastic modulus compared to the uncoated alloy. The hydrophobicity of the coated surface increased and showed a contact angle of ∼134 ± 3°, which is indicative of improved corrosion resistance. Electrochemical testing conducted in 3.5 wt.% NaCl solution revealed a significant improvement in the corrosion resistance of the chromium nitride-coated NAB, reflected in increased charge-transfer resistance and reduced double-layer capacitance, along with suppressed corrosion current density. Electrochemical impedance spectroscopy (EIS) confirms an enhanced barrier behaviour due to the presence of the dense nitride layer. These findings demonstrate that Cr2N coatings appear to be an effective surface engineering solution for enhancing corrosion resistance and mechanical strength and improving the surface quality of NAB components in potential marine and industrial applications.
To address the challenge of severe wear and substantial service life reduction of carbon-based solid lubricating coatings under harsh working conditions, this study adopts neopentyl glycol dioleate (NPGD) as green lubricant, and constructs solid-liquid composite lubrication systems by combining NPGD with hydrogenated amorphous carbon (a-C:H) films and non-hydrogenated amorphous carbon (a-C) films respectively. This paper systematically compares and investigates the influence of testing working conditions on the friction and wear properties of the two systems as well as their discrepancies. The results show that compared with the tribological performance of the films under dry friction, the friction coefficients of the two composite lubrication systems decrease significantly (by approximately 40%), and the wear rates reduce by 2 to 3 orders of magnitude (reaching 10-9 mm³/N·m under an applied load of 4 N), both exhibiting ultra-low wear performance. However, under high loads (15 N), the a-C/NPGD composite lubrication system has better wear resistance. It is found that during the friction process, due to the hydrogen passivation effect on the surface of a-C:H films, NPGD lubricant molecules only form a lubricating layer with low bearing capacity via their wettability and van der Waals force. In contrast, the surface of a-C films contains a large number of dangling bonds, which can form chemical bonds with the ester groups of NPGD, thereby generating a stable adsorption layer with high bearing capacity, leading to a more pronounced solid-liquid synergistic effect.
The low electrical conductivity of bulk copper oxide (CuO) hinders its application in photovoltaics. This work demonstrates that strategic codoping can simultaneously tune the structural, optical, and electrical properties of CuO thin films to overcome this limitation. We report the synthesis of Co/Zn, Co/Ni, and Co/Ag codoped CuO thin films via a modified successive ionic layer adsorption and reaction (M-SILAR) technique. Structural characterization by X-ray diffraction and Raman spectroscopy confirmed the formation of phase-pure monoclinic CuO, while the observed lattice parameter shifts were consistent with the incorporation of dopant ions into the CuO lattice. Morphological analysis using scanning electron microscopy showed that codoping refined the microstructure, converting undoped agglomerates into uniform nanospherical grains. The optical band gap was enhanced to a maximum of 1.64 eV for the Co/Zn codoped sample. Furthermore, this film exhibited superior electrical properties, with an optimal combination of high carrier density and mobility. Consequently, the Co/Zn codoped CuO thin film is identified as a highly suitable absorber layer for photovoltaic devices.
This study demonstrates a marked enhancement in the ferroelectricity of Hf1-xZrxO2 (HZO) films achieved by rapid cooling after rapid thermal annealing (RTA) crystallization. In a Mo/HZO/Mo capacitor stack, fast cooling in air or in deionized water nearly doubled the remanent polarization (2Pr=15.39 μC/cm2) compared with conventional in-chamber cooling after RTA at 400°C, without compromising reliability. Detailed analysis revealed a correlation between the cooling method and the phase composition of the HZO film. The quenching methods effectively suppressed the non-ferroelectric monoclinic phase, leading to a higher proportion of the ferroelectric orthorhombic phase, thereby increasing the overall polarization.
In this study, polysilicon films deposited via Low-Pressure Chemical Vapor Deposition were doped with phosphorus through POCl3 diffusion, and the depth-dependent distribution of electrically active dopants was investigated using a comprehensive characterization approach coupled with controlled etching steps. The initial film, approximately 450 nm thick, was progressively thinned through sequential etching, and at each stage, structural, chemical, optical, mechanical, and electrical properties were systematically evaluated. Raman spectroscopy confirmed the polycrystalline nature of the films, while Scanning Electron Microscopy revealed the microstructural evolution induced by doping and etching processes. Fourier Transform Infrared spectroscopy qualitatively identified phosphorus-related bonding; the absence of phosphorus-oxygen bonds in the gate oxide layer indicates that SiO2 maintains its role as an effective diffusion barrier. Profilometry measurements indicated that residual stress within the films increased as the thickness decreased. Sheet resistance values obtained from four-point probe measurements were used to calculate the resistivity and electrically active carrier concentration via semi-empirical physical relationships, allowing the depth-dependent evolution of electrical parameters to be assessed. The observed trends indicate that the electrically active carrier concentration is higher near the film surface and gradually decreases with depth. Technology Computer-Aided Design simulations employing a mobility model incorporating grain-boundary barrier effects reproduced the experimentally observed carrier transport behavior.This study demonstrates that, by combining etching-based characterization with multiple physical measurement techniques, the depth-dependent electrical behavior of doped polysilicon films can be holistically evaluated without requiring direct chemical profile analysis.
The boron-doped ZnO thin films are deposited on glass substrates by the method of spin coating. The crystalline quality is observed to degrade with an increase in the dopant concentration on account of the interstitial doping resulting from the difference in ionic radii between Zn2+and B3+. The observed gradual increase in bandgap was an indicative of the enhanced number of charge carriers and Fermi level shift. Modifications of nonlinear optical coefficients of ZnO thin films upon doping with boron were experimentally verified with Z-scan set up with nanosecond pulsed laser source. Pure Reverse Saturable Absorption (RSA) behaviour was exhibited by boron-incorporated ZnO films, yielding an exceptionally smaller optical limiting threshold of 7 mJ/cm2. Both nonlinear absorption and refraction measurements were carried out. This concentration-dependent study allowed the optimisation of concentration of boron, which resulted in the enhancement of the two-photon absorption coefficient.
Zr, V and Zr-V films were evaporated on silicon substrates for evaluating their gettering properties for microelectromechanical systems (MEMS) packaging. The film microstructure was characterized by scanning electron microscope, atomic force microscope, transmission electron microscopy, X-ray diffraction and electrical measurements. Films are amorphous or nanocrystallized according to their composition. Film samples were then activated at various temperatures under argon atmosphere at low pressure of oxidizing species. After annealing, oxygen sorption by the samples was measured by ion beam analysis. Finally, getter films were integrated inside MEMS vacuum packages with a maximum temperature of 300°C. An optimal gettering performance was obtained with the Zr85V15 alloy composition which is close to the limit of the amorphous zone in the phase diagram. For the amorphous films, no correlation is found between oxygen diffusivity and getter performance. The role of grain boundaries in the activation performance of Zr-V getter films was emphasized, by showing that increasing the density of grain boundary enhances the getter performance of the film until an optimum, above which a further increase becomes detrimental to the getter sorption properties. Below this optimum, the enhancement of getter performance by the increasing of grain boundary density can be modelled and allows to predict the getter performance of a Zr-V film knowing its microstructure.
The thermal decomposition characteristics of highly hydrogenated diamond-like carbon (H-DLC) films, which exhibit a low coefficient of friction in vacuum, were investigated in order to understand their thermal structural changes and decomposition process. The mass of the gas released by thermal decomposition of the highly H-DLC films was detected through thermal desorption spectroscopy to determine the starting temperature. The film with high hydrogen content started to desorb hydrogen at 360°C and desorb hydrocarbons between 400°C and 500°C. Moreover, highly H-DLC films were prepared by performing heat treatments at several annealing temperatures, and the structural changes in these films were plotted as a function of annealing temperature. At 360°C, where hydrogen desorption occurred, the sp2/(sp2+sp3) ratio of carbon near the surface increased. Between 400°C and 500°C, where hydrocarbon desorption occurred, the sp2/(sp2+sp3) ratio and vacancy-type defects increased significantly, whereas the film thickness and hydrogen content decreased substantially. Above 550°C, the entire film graphitized, resulting in no further change in the sp2/(sp2+sp3) ratio or vacancy-type defects, but a decrease in film thickness.
2H-WSe₂ films were synthesized by magnetron co-sputtering of tungsten and selenium targets onto SiO₂/Si(100), SiO₂/Si(111), and Al₂O₃(0001) substrates in an Ar atmosphere at 150°C, without any additional vacuum selenization step. After rapid thermal annealing at 700°C in Ar, x-ray diffraction confirmed the formation of the optimal crystal phase. Films grown on SiO₂/Si exhibited lower strain compared to those deposited on Al₂O₃. We demonstrated that ∼50 nm-thick (002)-textured WSe₂ films can be achieved while maintaining planar-like growth for film thicknesses below approximately 60 nm. Raman spectroscopy showed the characteristic E1₂g and A₁g modes of 2H-phase WSe₂ at 248 cm⁻¹ and 251 cm⁻¹, corresponding to in-plane and out-of-plane vibrational phonon modes, respectively. The indirect optical bandgap of few-layer WSe₂ was determined to be between 1.25 eV and 1.35 eV, with the bandgap varying as a function of film thickness—an expected property of 2D materials such as WSe₂.
Heterostructures combining layered chalcogenide thin films with ferroelectric oxide substrates provide an interesting platform for investigating substrate-driven modulation of electronic transport. In this work, Bi₂Te₃ thin films with a nominal thickness of approximately 10 nm were grown on BaTiO3 (001) substrates by molecular beam epitaxy. Reflection high-energy electron diffraction and X-ray diffraction reveal streaky diffraction features and dominant Bi2Te3 (00l) reflections, indicating highly c-axis-oriented growth with no detectable secondary phases. Temperature-dependent resistance measurements show a distinct anomaly near 281 K, close to the tetragonal-to-orthorhombic phase transition of BaTiO3. This correlation suggests that the structural transition of the ferroelectric substrate affects the electronic transport of the Bi₂Te₃ film, most likely through substrate-induced strain and domain-related lattice distortion. Upon further cooling below approximately 190 K, the resistance shows an abrupt increase associated with irreversible mechanical damage, and optical inspection after the measurement reveals visible cracking and partial delamination of the film. The low-temperature degradation is likely associated with accumulated thermal and phase-transition-induced stress at the Bi2Te3/BaTiO3 interface. These results show that BaTiO3 can modulate the transport response of Bi2Te3 thin films, while also imposing mechanical stability limitations during cooling. The findings provide useful insight for designing chalcogenide/ferroelectric oxide heterostructures for strain-sensitive electronic and thermoelectric devices.
In the field of fuel cell metal bipolar plates, TiN protective coatings typically provide adequate corrosion resistance but often lack sufficient electrical conductivity. To address this limitation and enhance the coating performance, this study introduces the doping of a controlled amount of metallic Ag into the TiN matrix. A series of Ag-doped TiN coatings with varying Ag concentrations were synthesized using a magnetron sputtering technique with an oscillating pulsed electric field. The influence of Ag on the conductivity and corrosion resistance of the TiN coating was systematically investigated. The results show that increasing the Ag target voltage from 360 V to 400 V raises the Ag doping concentration in the coating, achieving an Ag atomic ratio of up to 33.35%. Within the coating, Ag particles undergo spontaneous self-assembly, forming interconnected conductive channels that create a three-dimensional network resembling a neural structure. This architecture enhances the coating density, corrosion resistance, and electrical conductivity. At an Ag target voltage of 380 V, the coating exhibits the lowest contact resistance of 0.21 m Omega & sdot;cm-2.This study provides an effective strategy for the surface modification and practical application of metal bipolar plates in fuel cells, thereby facilitating the broader adoption and development of hydrogen fuel cell technology.
Oxidation of AlxGa1-xAs(100) surfaces with high (x - 0.9) and moderate (x - 0.3) aluminum content under exposure to room air (T - 20-25 degrees C; RH - 50-60%) is investigated by x-ray photoelectron spectroscopy in order to get insight into the composition of the formed native oxide layer and the rate of its formation depending of the aluminum content in the alloy. It is found that oxides on Al0.9Ga0.1As(100) and Al0.3Ga0.7As(100) surfaces are formed by different mechanisms under exposure to air. The Al0.9Ga0.1As(100) surface oxidizes continuously and after a month of air exposure the native oxide layer reaches a thickness of about 9 nm. This layer consists of aluminum and gallium oxides/hydroxides with prevailing amount of hydroxides, as well as elemental arsenic, while arsenic oxides are not found indicating that the main oxidant for this surface is the H2O molecules existing in humid air. On the Al0.3Ga0.7As(100) surface a stable native oxide layer of 2-3 nm thick is formed consisting of aluminum and gallium oxides, as well as of elemental arsenic and small amount of arsenic oxides, testifying that both O2 and H2O molecules take part in surface oxidation.
Reactive oxygen control during radio frequency magnetron sputtering governs the stoichiometry and protective performance of silicon dioxide (SiO2) coatings on Cu–Ag–Au alloys. In this work, SiO₂ thin films were deposited under varying Ar/O2 gas flow ratios to elucidate stoichiometry-driven mechanical strengthening and sulfidation resistance. X-ray photoelectron spectroscopy reveals that an intermediate oxygen ratio (Ar/O2 = 30:10) maximizes the fraction of fully oxidized Si⁴⁺ states, indicating the most complete oxidation state among the investigated conditions. This optimized condition produces a smooth and highly uniform surface morphology with minimized root mean square surface roughness of approximately 1.38 nm and significantly enhanced hardness (∼5.8 GPa), more than twice that of the uncoated alloy. Under oxygen-deficient or oxygen-rich conditions, increased oxygen vacancies and transport-limited growth reduce structural uniformity and mechanical integrity. Accelerated hydrogen sulfide exposure tests demonstrate that stoichiometric SiO2 effectively suppresses sulfidation, preventing the formation of Cu2S and Ag2S responsible for surface tarnishing. A three-regime growth model is proposed to describe the interplay between oxidation kinetics and adatom mobility, providing a mechanistic framework for designing high-performance oxide protective coatings.
(Ba, Ca)(Zr, Ti)O3 (BCZT) is a widely recognized perovskite piezoelectric oxide used in energy harvesting applications. In our current research, 0.5Ba(ZrxTi(1-x))O3 + 0.5(BayCa(1-y)) TiO3 (0.5BZT-0.5BCT) ferroelectric thin films were deposited by spin-coating onto Pt/Ti/SiO2/Si commercial substrates. The solutions were synthesized using the sol-gel processing method. Various precursors were selected for different compositions, and their impacts were carefully analysed. Multiple spin-coating cycles were employed, followed by drying and pyrolysis. The effect of composition for Ba:Ca and Zr:Ti on structural, microstructural, topographical, dielectric, and ferroelectric properties was examined. The evolution of dielectric permittivity and dielectric loss was recorded as a function of frequency (f) from 20 Hz to 1 MHz. The optimized 0.5BZT-0.5BCT exhibited stable dielectric values over a wide frequency range, with a high dielectric permittivity of ∼1020 and a low dielectric loss of ∼0.02 at 100 kHz. The obtained results were discussed in comparison with earlier reports. Polarization (P) as a function of electric field (E) hysteresis curves demonstrated the ferroelectric nature of the thin films, with no excess leakage current. The high and stable dielectric permittivity and low dielectric losses over a large frequency range presented in our work suggest that 0.5Ba(Zr0.1Ti0.9)O3 + 0.5(Ba0.85Ca0.15)TiO3 oxide is a suitable candidate for the development of energy harvesting devices.
Nickel monosilicide (NiSi) thin films are of interest for interconnect and contact applications; however, achieving continuous thin films that remain stable under the investigated annealing conditions at reduced thickness remains challenging because of agglomeration during silicidation. In this study, NiSi films were formed on oxidized Si substrates via the solid-state reaction of amorphous Si/Ni (a-Si/Ni) bilayers with varying thicknesses. Microstructural and compositional analyses reveal that uniform, continuous, and polycrystalline NiSi films can be obtained without detectable residual Ni or Si, even at thicknesses as low as ∼17 nm. The use of amorphous Si facilitates homogeneous silicidation, thereby reducing the tendency for agglomeration commonly observed in polycrystalline Si-based systems. A Ni-enriched interfacial region is consistently observed at the NiSi/SiO2 interface, which is attributed to Ni accumulation during silicidation. The films exhibit low electrical resistivity (∼30 μΩ·cm after annealing at 700°C), along with stable phase and morphology without degradation after annealing at 700°C for 1 h. These results suggest that the a-Si/Ni bilayer configuration is a promising approach for forming continuous NiSi films in the nanoscale thickness regime with favorable structural and electrical properties.
As copper interconnects scale to sub-20-nm dimensions, pronounced resistivity escalation and electromigration (EM) degradation necessitate alternative metallization material approaches, among which bamboo-like grain structures have emerged as a highly effective microstructural route for suppressing EM by blocking fast grainboundary diffusion pathways. Although cobalt exhibits favorable resistivity scaling, its conventional equiaxed grain structure limits EM reliability, motivating the development of alloy systems capable of naturally forming bamboo-like grains while preserving low residual resistivity. In this study, CoNi alloy thin films and interconnect lines with controlled Ni contents were fabricated by co-sputtering and systematically characterized through thermal annealing, electrical stressing, nanomechanical measurements, and transmission electron microscopy. The optimized CoNi interconnects develop a pronounced bamboo-like grain morphology, resulting in more than a twofold increase in EM lifetime, together with a reduced current-density scaling factor (n = 0.30) and an elevated activation energy (1.62 eV) compared with pure Co lines. Concurrently, Ni incorporation enhances interfacial adhesion strength, hardness, and dielectric integrity, collectively suppressing grain-boundary and interfacial diffusion that governs EM failure. These findings demonstrate that exploiting bamboo-grain formation through fully miscible CoNi alloys provides a robust and scalable pathway for EM-resistant interconnects in nextgeneration back-end-of-line technologies.
We report effective control of the metal–to–insulator transition (MIT) temperature in polycrystalline VO2 thin films grown on flexible μ–sheet glass substrate by applying uniaxial compressive stress during deposition. The MIT temperature decreases from 334.5 K to 328.0 K, 324.5 K, and 321.5 K under applied compressive stresses of 0.11, 0.13 and 0.18 GPa, respectively, corresponding to an average stress sensitivity of approximately 0.07 K/MPa, which is attributed to weakened Peierls–type dimerization. This exceptionally high sensitivity demonstrates that even MPa-level stresses, achievable by bending the supporting substrate, are sufficient to tune the transition temperature. Our findings provide a practical route for engineering the MIT in VO2 through ultralow–strain engineering, thereby enabling industrial applications such as flexible thermochromic devices.
