Search Results (3,072)

This study examines copper thin films under tensile stress and their shape and percentage change in electrical resistance (PCER) as a function of applied strain. Copper films of 100 and 200 nm thickness were sputtered onto polyethylene terephthalate (PET) substrates and were then sequentially stretched to examine how film thickness affects strain-induced morphological changes and electrical resistance. A scanning electron microscope (SEM) was used to track crack patterns, and electrical resistance was monitored throughout tensile testing. Thinner films (100 nm) had quick crack initiation and propagation, leading to an increase in PCER under strain, while thicker films (200 nm) had more gradual morphological and electrical resistance changes. This differential reaction demonstrates the importance of film thickness in mechanical deformation and strain sensitivity, which could affect the design of flexible electronic devices that require mechanical durability and reliable electrical performance. These findings will help to optimize film thickness for stretchable sensors and wearable electronics to balance strain sensitivity and morphological degradation. This study will help designers and users of sensors, stretchable electronics, and other devices that require mechanical durability and electrical performance to understand the relationship between mechanical deformation and electrical properties in thin films. This paper aligns with the ninth goal of the United Nations Sustainable Development Goals, specifically Target 9.5: Enhance Research and Upgrade Industrial Technologies. Full article

Thermal treatment is a common method to improve the properties of optical thin films, but improper thermal treatment processing will result in the degradation of the optical properties of the optical thin film. The thermal stability of niobium oxide (Nb₂O₅) thin films prepared by magnetron sputtering was systematically studied by analyzing the roughness and morphology of the film under different thermal treatment processes. The results show that the amorphous stability of the Nb₂O₅ thin film can be maintained up to 400 °C. Before crystallization, with an increase in annealing temperature, the surface roughness of the film has no obvious change, the refractive index decreases, and the elastic modulus and hardness increase. The residual stress was measured by a laser interferometer. The results show that the residual compressive stress is present in the film, and the residual stress decreases with an increase in thermal treatment temperature. Considering the residual stress state, phase composition, mechanical properties, and optical properties of Nb₂O₅ films at different thermal treatment temperatures, we believe that the spectral position of the optical thin film device can be finely controlled within a 1.6% wavelength, and the thermal treatment temperature of Nb₂O₅ films prepared by magnetron sputtering should not exceed 400 °C. Full article

Optical fiber sensors have emerged as a critical sensing technology across various fields due to their advantages, including high potential bandwidth, electrical isolation that is safe for utilization in electrically hazardous environments, high reliability, and ease of maintenance. However, conventional optical fiber sensors face limitations in achieving high sensitivity and precision. The integration of nanostructures with advanced coating technology is one of the critical solutions to enhancing sensor functionality. This review examined nanostructure coating techniques that are compatible with optical fiber sensors and evaluated etching techniques for the improvement of optical fiber sensing technology. Techniques such as vapor deposition, laser deposition, and sputtering to coat the nanostructure of novel materials on the optical fiber sensors are analyzed. The ability of optical fiber sensors to interact with the environment via etching techniques is highlighted by comparing the sensing parameters between etched and bare optical fibers. This comprehensive overview aims to provide a detailed understanding of nanostructure coating and etching for optical fiber sensing and offer insights into the current state and future prospects of optical fiber sensor technology for sensing performance advancement, emphasizing its potential in future sensing applications and research directions. Full article

The electrical, stability and optoelectronic properties of GZTO TFTs with different Ga doping concentrations were investigated. Active layers were prepared by co-sputtering GaO and ZTO targets with different sputtering powers. The experimental results show that the surface of GZTO films is smooth, which is favorable for stability. The off-state current is reduced by a factor of 10, the switching ratio is increased to 1.59 × 10⁸, and the threshold voltage shift is reduced in PBS and NBS tests. In addition, the transmittance of all devices is greater than 80% in the visible range, and the optical bandgap of the TFTs is increased from 3.61 eV to 3.84 eV after Ga doping. The current enhancement of the GZTO TFTs is more pronounced under UV irradiation, with higher responsiveness and better-sustained photoconductivity. It is proved that Ga doped into ZTO as a carrier suppressor can better combine with oxygen vacancies and reduce the concentration of oxygen vacancies and oxygen defects compared with Zn and Sn atoms, thus improving stability. GaO, as a wide bandgap material, can improve the optical bandgap of GZTO TFTs so that they can better absorb the light in the UV wavelength band, and they can be used in the field of UV photodetection. Full article

A solid solution is an effective approach to regulate the microstructure and hence the various properties such as hardness and oxidation behavior of materials. In this study, an M-site solid-solution medium-entropy-alloy MAX-phase coating (TiVCr)₂AlC was prepared through combining the magnetron sputter deposition at low- and high-temperature vacuum annealing. The mechanical properties and high-temperature oxidation resistance in the 700–1000 °C temperature range in air of these coatings were then evaluated. The results showed that the 211-MAX-phase can be formed in the 700 °C vacuum for 3 h, and the crystallinity depended on the annealing temperature. Compared to the amorphous coating, the MAX-phase sample demonstrated superior oxidation resistance in terms of the onset temperature of the oxidation and the oxidation products. During high-temperature oxidation, a mixed oxide layer containing V₂O₅, TiO₂, and Cr₂O₃ was formed at 700 °C on the surface of an amorphous coating, whereas only a thin continuous Al₂O₃ scale was observed at ≤800 °C for the crystalline (TiVCr)₂AlC coating. Additionally, the maximum hardness of the coating reached 18 GPa after annealing. These results demonstrate the application potential of the medium-entropy-alloy MAX-phase coating in extreme environments such as aerospace, nuclear energy, and other fields. Full article

This paper presents the results of a study on the characteristics of semiconductor sensors based on thin SnO₂ films modified with antimony, dysprosium, and silver impurities and dispersed double Pt/Pd catalysts deposited on the surface to detect carbon monoxide (CO). An original technology was developed, and ceramic targets were made from powders of Sn-Sb-O, Sn–Sb-Dy–O, and Sn–Sb-Dy-Ag–O systems synthesized by the sol–gel method. Films of complex composition were obtained by RF magnetron sputtering of the corresponding targets, followed by technological annealing at various temperatures. The morphology of the films, the elemental and chemical composition, and the electrical and gas-sensitive properties were studied. Special attention was paid to the effect of the film composition on the stability of sensor parameters during long-term tests under the influence of CO. It was found that different combinations of concentrations of antimony, dysprosium, and silver had a significant effect on the size and distribution of nanocrystallites, the porosity, and the defects of films. The mechanisms of degradation under prolonged exposure to CO were examined. It was established that Pt/Pd/SnO₂:0.5 at.% Sb film with optimal crystallite sizes and reduced porosity provided increased stability of carbon monoxide sensor parameters, and the response to the action of 100 ppm carbon monoxide was G₁/G₀ = 2–2.5. Full article

Integrating nanocrystalline diamond (NCD) films on silicon chips has great practical significance and many potential applications, including high-power electronic devices, microelectromechanical systems, optoelectronic devices, and biosensors. In this study, we provide a solution for ensuring heterogeneous interface integration between silicon (Si) chips and NCD films using low-temperature bonding technology. This paper details the design and implementation of a magnetron sputtering layer on an NCD surface, as well as the materials and process for the connection layer of the integrated interface. The obtained NCD/Ti/Cu composite layer shows uniform island-like Cu nanostructures with 100~200 nm diameters, which could promote bonding between NCD and Si chips. Ultimately, a heterogeneous interface preparation of Si/Ag/Cu/Ti/NCD was achieved, with the integration temperature not exceeding 250 °C. The TEM analysis shows the closely packed atomic interface of the Cu NPs and deposited Ti/Cu layers, revealing the bonding mechanism. Full article

Materials consisting of quantum dots with a semiconductor-core, metal–shell structure often have exciting and tunable photo-electrical properties in a large range of values, and they are adjustable by core and shell structure parameters. Here, we investigated the influence of Mn-shell addition to Ge quantum dots formed in an alumina matrix by magnetron sputtering deposition. We show a well-achieved formation of the 3D regular lattices of Ge-core, Mn-rich shell quantum dots, which were achieved by self-assembled growth mode. Intermixing of Ge and Mn in the shell was observed. The optical, electrical, and photo-conversion properties were strongly affected by the addition of the Mn shell and its thickness. The shell induced changes in the optical gap of the materials and caused an increase in the material’s conductivity. The most significant changes occurred in the photo-electrical properties of the materials. Their quantum efficiency, i.e., the efficiency of the conversion of photon energy to the electrical current, was very strongly enhanced by the shell addition, though it depended on its thickness. The best results were obtained for the thinnest shell added to the Ge core, for which the maximal quantum efficiency was significantly enhanced by more than 100%. The effect was, evidently, the consequence of multiple exciton generation, which was enhanced by the shell addition. The obtained materials offer great potential for various applications in photo-sensitive devices. Full article

This paper presents the results of experimental studies of the influence of high-frequency magnetron sputtering power on the structural and electrophysical properties of nanocrystalline ZnO films. It is shown that at a magnetron sputtering power of 75 W in an argon atmosphere at room temperature, ZnO films have a relatively smooth surface and a uniform nanocrystalline structure. Based on the results obtained, the formation and study of resistive switching of transparent ITO/ZnO/ITO memristor structures as well as a crossbar array based on them were performed. It is demonstrated that memristor structures based on ZnO films obtained at a magnetron sputtering power of 75 W exhibit stable resistive switching for 1000 cycles between high resistance states (HRS = 537.4 ± 26.7 Ω) and low resistance states (LRS = 291.4 ± 38.5 Ω), while the resistance ratio in HRS/LRS is ~1.8. On the basis of the experimental findings, we carried out mathematical modeling of the resistive switching of this structure, and it demonstrated that the regions with an increase in the electric field strength along the edge of the upper electrode become the main sources of oxygen vacancy generation in ZnO film. A crossbar array of 16 transparent ITO/ZnO/ITO memristor structures was also fabricated, demonstrating 20,000 resistive switching cycles between LRS = 13.8 ± 1.4 kΩ and HRS = 34.8 ± 2.6 kΩ for all devices, with a resistance ratio of HRS/LRS of ~2.5. The obtained results can be used in the development of technological processes for the manufacturing of transparent memristor crossbars for neuromorphic structures of machine vision, robotics, and artificial intelligence systems. Full article

High-performance acoustic resonators based on single-crystalline piezoelectric thin films have great potential in wireless communication applications. This paper presents the modeling, fabrication, and characterization of laterally excited bulk resonators (XBARs) utilizing the suspended ultra-thin (~420 nm) LiTaO₃ (LT, with 42° YX-cut) film. The finite element analysis (FEA) was performed to model the LT-based XBARs precisely and to gain further insight into the physical behaviors of the acoustic waves and the loss mechanisms. In addition, the temperature response of the devices was numerically calculated, showing relatively low temperature coefficients of frequency (TCF) of ~−38 ppm/K for the primary resonant mode. The LT-based XBARs were fabricated and characterized, which presents a multi-resonant mode over a wide frequency range (0.1~10 GHz). For the primary resonance around 4.1 GHz, the fabricated devices exhibited a high-quality factor (Bode-Q) ~ 600 and piezoelectric coupling (k_t²) ~ 2.84%, while the higher-harmonic showed a greater value of k_t² ~ 3.49%. To lower the resonant frequency of the resonator, the thin SiO₂ film (~20 nm) was sputtered on the suspended device, which created a frequency offset between the series and shunt resonators. Finally, a ladder-type narrow band filter employing five XBARs was developed and characterized. This work effectively demonstrates the performance and application potential of micro-acoustic resonators employing high-quality LT films. Full article

This study aimed to develop a technology for synthesizing non-degrading porous coatings that remain stable under the conditions of outer space. Using the magnetron sputtering method, we obtained vanadium–lead system coatings over a wide range of mutual concentrations from 6 to 44.9 at. % Pb. X-ray and electron microscopic studies were conducted on the obtained coatings. As a result of the research, a dependence of the film structure on changes in the lead concentration in vanadium was demonstrated. A correlation between the lead concentration in vanadium, the size of the resulting crystallites of solid solutions, and the change in the lattice parameter of the solid solution depending on the lead concentration in the coating was identified. A new possibility of producing porous vanadium coatings through vacuum annealing of the obtained alloy-based coatings in the V-Pb system was shown. Full article

Ceramic materials as coatings are known to have very good corrosion resistance properties compared to metallic or organic coatings, regardless of environmental conditions. The following samples were used for the experiments: an initial steel substrate and Al₂O₃ + YSZ (12.5%; 25% and 37.5% wt) atmospheric plasma spray-coated samples. The open circuit potential showed similar average values for all samples coated with ceramic layers, which were slightly higher than the potential of the original uncoated sample. The corrosion current densities (i_corr) of all plasma jet sputter-coated systems were very similar and significantly lower than those of the original material. Corrosion rates were much lower in the coated systems due to the chemical inertness of the ceramic coatings, particularly alumina- and zirconia-based coatings. It was observed that ceramic layers improve the corrosion resistance of the metallic material, especially at higher percentages of YSZ in the plasma spray-deposited complex layer. The porosity of the sputter-deposited layers reduced their corrosion resistance due to the contact between the electrolyte solution and the metal substrate created by the interconnection of the pores. The complex equivalent electrical circuit chosen for the analysis of the values led to results in accordance with the experimental parameters. Full article

This study aimed to investigate the degradation of dry biopotential electrodes using the anodic stripping voltammetry (ASV) technique. The electrodes were based on Ti-Cu thin films deposited on different polymeric substrates (polyurethane, polylactic acid, and cellulose) by Direct Current (DC) magnetron sputtering. TiCu_0.34 thin films (chemical composition of 25.4 at.% Cu and 74.6 at.% Ti) were prepared by sputtering a composite Ti target. For comparison purposes, a Cu-pure thin film was prepared under the same conditions and used as a reference. Both films exhibited dense microstructures with differences in surface topography and crystalline structure. The degradation process involved immersing TiCu_0.34 and Cu-pure thin films in artificial sweat (prepared following the ISO standard 3160-2) for different durations (1 h, 4 h, 24 h, 168 h, and 240 h). ASV was the technique selected to quantify the amount of Cu(II) released by the electrodes immersed in the sweat solution. The optimal analysis conditions were set for 120 s and −1.0 V for time deposition and potential deposition, respectively, with a quantification limit of 0.050 ppm and a detection limit of 0.016 ppm. The results showed that TiCu_0.34 electrodes on polyurethane substrates were significantly more reliable over time compared to Cu-pure electrodes. After 240 h of immersion, the TiCu_0.34 electrodes released a maximum of 0.06 ppm Cu, while Cu-pure electrodes released 16 ppm. The results showed the significant impact of the substrate on the electrode’s longevity, with cellulose bases performing poorly. TiCu_0.34 thin films on cellulose released 1.15 µg/cm² of copper after 240 h, compared to 1.12 mg/cm² from Cu-pure films deposited on the same substrate. Optical microscopy revealed that electrodes based on polylactic acid substrates were more prone to corrosion over time, whereas TiCu thin-film metallic glass-like structures on PU substrates showed extended lifespan. This study underscored the importance of assessing the degradation of dry biopotential electrodes for e-health applications, contributing to developing more durable and reliable sensing devices. While the study simulated real-world conditions using artificial sweat, it did not involve in vivo measurements. Full article

We examined how controlling variables in a pre-metallization Ar sputter-etching process for in situ contact-hole cleaning affects the contact-hole profile, etching rate, and substrate damage. By adjusting process parameters, we confirmed that increasing plasma power lowered the DC bias but enhanced the etching rate of SiO₂, while increasing RF power raised both, with RF power having a more pronounced effect. Higher Ar flow rate reduced etching uniformity and slightly lowered the DC bias. There was no significant difference in the amount of etching between the oxide film types, but the nitride/oxide selectivity ratio was about 1:2. Physical damage during Ar sputter-etching was closely linked to DC bias. finally, Finally, etching of the Si and CoSi₂ sublayers was performed on the device contact hole model. At this time, Si losses of up to about 31.7 Å/s occurred, and the etch speed was strongly affected by the DC bias. By optimizing the RF power and plasma power, we achieved a Si/CoSi₂ etch selectivity ratio of about 1:2. Full article

Uncrystallized indium-gallium-zinc-oxide (InGaZnO) thin-film transistors (TFTs) combined with an aluminum nitride (AlN) dielectric have been used to promote performance and steadiness. However, the high deposition temperature of AlN films limits their application in InGaZnO flexible TFTs. In this work, AlN layers were deposited via low-temperature plasma-enhanced atomic layer deposition (PEALD), and InGaZnO films were fabricated via high-power impulse magnetron sputtering (HIPIMS). The band alignment of the AlN/InGaZnO heterojunction was studied using the X-ray photoemission spectrum and ultraviolet visible transmittance spectrum. It was found that the AlN/InGaZnO system exhibited a staggered band alignment with a valence band offset ΔE_v of −1.25 ± 0.05 eV and a conduction band offset ΔE_c of 4.01 ± 0.05 eV. The results imply that PEALD AlN could be more useful for surface passivation than a gate dielectric to promote InGaZnO device reliability under atmospheric exposure. Full article