Search Results (223)

We present a neural-network-based approach to solve the image-to-image translation problem in microscale droplets squeeze flow. A residual convolutional neural network is proposed to address the inverse problem: reconstructing a low-resolution (LR) droplet pattern image from a high-resolution (HR) liquid film thickness imprint. This enables the prediction of initial droplet configurations that evolve into target HR imprints after a specified spreading time. The developed neural network architecture aims at learning to tune the refinement level of its residual convolutional blocks by using function approximators that are trained to map a given film thickness to an appropriate refinement level indicator. We use multiple stacks of convolutional layers, the output of which is translated according to the refinement level indicators provided by the directly connected function approximators. Together with a non-linear activation function, the translation mechanism enables the HR imprint image to be refined sequentially in multiple steps until the target LR droplet pattern image is revealed. We believe that this work holds value for the semiconductor manufacturing and packaging industry. Specifically, it enables desired layouts to be imprinted on a surface by squeezing strategically placed droplets with a blank surface, eliminating the need for customized templates and reducing manufacturing costs. Additionally, this approach has potential applications in data compression and encryption. Full article

100 nm thick TiO₂/TiN bilayers with varying thickness ratios were deposited via reactive sputtering of a Ti target in controlled oxygen and nitrogen atmospheres. Post-deposition annealing in air at 600 °C was performed to induce nitrogen diffusion through the oxygen-deficient TiO₂ layer. The resulting changes in morphology and chemical environment were investigated in detail using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-Vis spectroscopy. Detailed TEM and XPS analyses have confirmed nitrogen diffusion across the TiO₂ layer, with surface nitrogen concentration and the ratio of interstitial to substitutional nitrogen dependent on the TiO₂/TiN mass ratio. Optical studies demonstrated modifications in optical constants and a reduction of the effective bandgap from 3.2 eV to 2.6 eV due to new energy states introduced by nitrogen doping. Changes in surface free energy induced by nitrogen incorporation showed a correlation to nitrogen doping sites on the surface, which had positive effects on overall photocatalytic activity. Photocatalytic activity, assessed through methylene blue degradation, showed enhancement attributed to nitrogen doping. Additionally, deposition of a 5 nm gold layer on the annealed sample enabled investigation of synergistic effects between nitrogen doping and gold incorporation, resulting in further improved photocatalytic performance. These findings establish the TiO₂/TiN bilayer as a versatile platform for supporting thin gold films with enhanced photocatalytic properties. 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

Recently, with the development of automation technology in various fields, much research has been conducted on infrared photodetectors, which are the core technology of LiDAR sensors. However, most infrared photodetectors are expensive because they use compound semiconductors based on epitaxial processes, and they have low safety because they use the near-infrared (NIR) region that can damage the retina. Therefore, they are difficult to apply to automation technologies such as automobiles and factories where humans can be constantly exposed. In contrast, short-wavelength infrared photodetectors based on PbS QDs are actively being developed because they can absorb infrared rays in the eye-safe region by controlling the particle size of QDs and can be easily and inexpensively manufactured through a solution process. However, PbS QDs-based SWIR photodetectors have low chemical stability due to the electron/hole extraction layer processed by the solution process, making it difficult to manufacture them in the form of patterning and arrays. In this study, bulk NiO and ZnO were deposited by sputtering to achieve uniformity and patterning of thin films, and the performance of PbS QDs-based photodetectors was improved by optimizing the thickness and annealing conditions of the thin films. The fabricated photodetector achieved a high response characteristic of 114.3% through optimized band gap and improved transmittance characteristics. Full article

We investigated a novel natural dye-sensitized solar cell (DSSC) utilizing gadolinium ruthenate pyrochlore oxide Gd₂Ru₂O₇ (GRO) as a photoanode and compared its performance to the TiO₂-Gd₂Ru₂O₇ (TGRO) combined-layer configuration. The films were fabricated using the spin-coating technique, resulting in spherical grains with an estimated mean diameter of 0.2 µm, as observed via scanning electron microscopy (SEM). This innovative photoactive gadolinium ruthenate pyrochlore oxide demonstrated strong absorption in the visible range and excellent dye adhesion after just one hour of exposure to natural dye. X-ray diffraction confirmed the presence of the pyrochlore phase, where Raman spectroscopy identified various vibration modes characteristic of the pyrochlore structure. Incorporating Gd₂Ru₂O₇ as the photoanode significantly enhanced the overall efficiency of the DSSCs. The device configuration FTO/compact-layer/Gd₂Ru₂O₇/Hibiscus-sabdariffa/electrolyte(I⁻/I₃⁻)/Pt achieved a high efficiency of 9.65%, an open-circuit voltage (Voc) of approximately 3.82 V, and a current density of 4.35 mA/cm² for an active surface area of 0.38 cm². A mesoporous TiO₂-based DSSC was fabricated under the same conditions for comparison. Using impedance spectroscopy and cyclic voltammetry measurements, we provided evidence of the mechanism of conductivity and the charge carrier’s contribution or defect contributions in the DSSC cells to explain the obtained Voc value. Through cyclic voltammetry measurements, we highlight the redox activities of hibiscus dye and electrolyte (I⁻/I₃⁻), which confirmed electrochemical processes in addition to a photovoltaic response. The high and unusual obtained Voc value was also attributed to the presence in the photoanode of active dipoles, the layer thickness, dye concentration, and the nature of the electrolyte. Full article

This study investigates the development and sensing profile of synthetic melanin nanoparticle-coated electrodes for the electrochemical detection of heavy metals, including lead (Pb), cadmium (Cd), cobalt (Co), zinc (Zn), nickel (Ni), and iron (Fe). Synthetic melanin films were prepared in situ by the deacetylation of diacetoxy indole (DAI) to dihydroxy indole (DHI), followed by the deposition of DHI monomers onto indium tin oxide (ITO) and glassy carbon electrodes (GCE) using cyclic voltammetry (CV), forming a thin layer of synthetic melanin film. The deposition process was characterized by electrochemical quartz crystal microbalance (EQCM) in combination with linear sweep voltammetry (LSV) and amperometry to determine the mass and thickness of the deposited film. Surface morphology and elemental composition were examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). In contrast, Fourier-transform infrared (FTIR) and UV–Vis spectroscopy confirmed the melanin’s chemical structure and its polyphenolic functional groups. Differential pulse voltammetry (DPV) and amperometry were employed to evaluate the melanin films’ electrochemical activity and sensitivity for detecting heavy metal ions. Reproducibility and repeatability were rigorously assessed, showing consistent electrochemical performance across multiple electrodes and trials. A comparative analysis of ITO, GCE, and graphite electrodes was conducted to identify the most suitable substrate for melanin film preparation, focusing on stability, electrochemical response, and metal ion sensing efficiency. Finally, the applicability of melanin-coated electrodes was tested on in-house heavy metal water samples, exploring their potential for practical environmental monitoring of toxic heavy metals. The findings highlight synthetic melanin-coated electrodes as a promising platform for sensitive and reliable detection of iron with a sensitivity of 106 nA/ppm and a limit of quantification as low as 1 ppm. Full article

Materials formed with a base of silk fibroin (SF) are successfully used in tissue engineering since their properties are similar to those of natural extracellular matrixes. Mixing SF with different polymers, for example, polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP), allows the production of fibers, hydrogels, and films and their morphology to be controlled. The impact of PEO and PVP on formation and structure of SF adsorption layers was studied at different was studied at different polymer concentrations (from 0.002 to 0.5 mg/mL) and surface lifetimes. The protein concentration was fixed at 0.02 and 0.2 mg/mL. These concentrations are characterized by different types of spontaneously formed structures at the air–water interface. Since both synthetic polymers possess surface activity, they can penetrate the fibroin adsorption layer, leading to a decrease in the dynamic surface elasticity at almost constant surface tension and a decrease in ellipsometric angle Δ and adsorption layer thickness. As shown by AFM, the presence of polymers increases the porosity of the adsorption layer, due to the possible arrangement of protein and polymer molecules into separate domains, and can result in various morphology types such as fibers or tree-like ribbons. Therefore, polymers like PEO and PVP can be used to regulate the SF self-assembly at the interface, which in turn can affect the properties of the materials with high surface areas like electrospun matts and scaffolds. Full article

Atomic layer deposition (ALD) has emerged as an essential technique, enabling the deposition of titanium nitride (TiN), which is renowned for its exceptional metal diffusion barrier properties. Improving within-wafer uniformity has become increasingly important to actively transition from lab-scale process development to wafer manufacturing. We considered the effect of gas velocity on thickness uniformity through computational fluid dynamics (CFD) simulations. Gas velocity was controlled by varying equipment design parameters, and it was confirmed that the resulting reduction in velocity improved both velocity and thickness uniformity. To validate the simulation results, an ALD reactor was experimentally performed under the same design and process conditions. The measured thickness of the deposited films confirmed an improvement in thickness uniformity, and the cause of the thickness reduction was further investigated. This study demonstrates that controlling gas velocity prov ides valuable insights into improving thickness uniformity in the ALD reactor. It confirms the effectiveness of simulations in overcoming the limitations associated with considering various process and equipment variables, which can be time-consuming and costly. Furthermore, it emphasizes the importance of integrating flow dynamic simulations with process evaluations to contribute to the advancement of semiconductor manufacturing technologies. Full article

As the typical representative of amorphous oxide semiconductors (AOS), quaternary indium gallium zinc oxide (IGZO) has been applied as the active layer of thin-film transistors (TFTs), but their mobility is still low (usually ~10 cm²/Vs). IGTO is reported to have larger mobility owing to the addition of Tin (Sn) in IZO. So, whether Sn doping can increase the optoelectronic properties of IGZO is a new topic worth studying. In this study, four series of quinary InGaZnSnO (IGZTO) oxide thin films were deposited on glass substrates using a high-purity IGZTO (In:Ga:Zn:Sn:O = 1:0.5:1.5:0.25:x, atomic ratio) ceramic target by RF magnetron sputtering. The effects of fabrication parameters (sputtering power, argon gas flow, and target-to-substrate distance) and film thickness on the microstructure, optical, and electrical properties of IGZTO thin films were investigated. The results show that all IGZTO thin films deposited at room temperature (RT) are amorphous and have a smooth and uniform surface with a low roughness (RMS of 0.441 nm, RA of 0.332 nm). They exhibit good average visible light transmittance (89.02~90.69%) and an optical bandgap of 3.47~3.56 eV. When the sputtering power is 90 W, the argon gas flow rate is 50 sccm, and the target-to-substrate distance is 60 mm, the IGZTO films demonstrate optimal electrical properties: carrier concentration (3.66 × 10¹⁹ cm⁻³), Hall mobility (29.91 cm²/Vs), and resistivity (0.54 × 10⁻² Ω·cm). These results provide a valuable reference for the property modulation of IGZTO films and the potential application in optoelectronic devices such as TFTs. Full article

Nanoplasmonic structures have emerged as a promising approach to address light trapping limitations in thin-film optoelectronic devices. This study investigates the integration of metallic nanoparticle arrays onto nanocrystalline silicon (nc-Si:H) thin films to enhance optical absorption through plasmonic effects. Using finite-difference time-domain (FDTD) simulations, we systematically optimize key design parameters, including nanoparticle geometry, spacing, metal type (Ag and Al), dielectric spacer material, and absorber layer thickness. The results show that localized surface plasmon resonances (LSPRs) significantly amplify near-field intensities, improve forward scattering, and facilitate coupling into waveguide modes within the active layer. These effects lead to a measurable increase in integrated quantum efficiency, with absorption improvements reaching up to 30% compared to bare nc-Si:H films. The findings establish a reliable design framework for engineering nanoplasmonic architectures that can be applied to enhance performance in photovoltaic devices, photodetectors, and other optoelectronic systems. Full article

The in situ electrochemical behaviors of Ti-39Nb-6Zr alloy were investigated in 2.3 ppm Li⁺ and 1500 ppm B³⁺ solution at 300 °C and 14 MPa. The activation energy is 12.84 kJ/mol, and the oxidation of titanium is controlled by oxygen ions diffusion in the liquid phases. The morphology, phase structure, and composition of the oxide film after 700 h exposure time in 300 °C and 14 MPa solution were characterized. The oxide film mainly included anatase TiO₂ phases, ZrO₂, Nb₂O₅, and a slight B₂O₃. The morphology of the film is shown by many nanocrystalline grains and the thickness is about 5 μm. The passivation film on the alloy substrate transforms from a single-layer film structure to a double-layer film structure. The impedance of the passivation decreases with the increase in temperature, which is related to the enhanced ion conductivity of the passivation film at high temperatures. The impedance of the dense layer inside the passivation film is much greater than that of the loose layer outside, and the dense layer inside plays a crucial role in the corrosion resistance of the Ti-39Nb-6Zr alloy. During the insulation process, the impedance of the dense layer inside the passivation film first increases and then slowly decreases, and the corrosion resistance of the passivation film first increases and decreases. Full article

Effective thermal management is a critical challenge in achieving high-power output for semiconductor laser devices. A key factor in laser device packaging is the bonding between the laser device on a GaAs substrate and a heat spreader, typically composed of high thermal conductivity materials such as SiC. Conventional soldering methods introduce thick bonding layers with relatively low thermal conductivity, resulting in high thermal resistance at the interface. In this study, we demonstrate the room temperature bonding of GaAs and SiC via a 30 nm thick Au layer, eliminating the need for a thermal reaction bonding layer or vacuum process. Using surface-activated bonding (SAB), GaAs and SiC were successfully bonded, with a strength comparable to bulk fracture. A uniform and ultrathin Au bonding interface significantly reduces thermal resistance compared to conventional soldering methods. These results highlight the potential of SAB with thin Au films as a promising approach for improving thermal management in high-power semiconductor laser devices. Full article

Fungal infections pose a significant global health problem, affecting 20–25% of the population and contributing to over 3.75 million deaths annually. Clotrimazole (CLO) is a widely used topical antifungal drug, but its efficacy is limited by poor penetration through the stratum corneum. Microneedle (MN) systems, composed of micron-scale structures arranged on a patch, offer a promising strategy to overcome the outermost skin barrier and enhance drug penetration into deeper layers. However, optimizing MN design, particularly in terms of size, shape, and fabrication technology, is essential for efficient drug delivery. This study aimed to develop CLO-coated MN systems using an Liquid Crystal Display (LCD)-based 3D printing technique and a thin-film dip-coating method. A comprehensive optimization of printing parameters, including anti-aliasing, layer thickness, curing time, and printing angle, was conducted to ensure the desired mechanical properties. The optimized MNs were coated with either suspension or ethanol-based CLO-hydrogels, with ethanol hydrogel demonstrating superior characteristics. Additionally, the study investigated how microneedle geometry and coating formulation influenced drug release. Antifungal activity against reference and clinical origin Candida albicans strains varied significantly depending on the coating formulation. Finally, the acute toxicity test confirmed no significant toxic effects on Aliivibrio fischeri, indicating the potential biocompatibility and safety of the developed MN-based drug delivery system. Full article

This paper presents a novel approach for fabricating porous NiO films decorated with nanowires, achieved through sputtering followed by thermal oxidation of a metallic layer. Notably, we successfully fabricate NiO nanowires using this simple and cost-effective method, demonstrating its potential applicability in the gas-sensing field. Furthermore, by using the film of our nanowires, we are able to easily prepare NiO sensors and deposit the required Pt electrodes directly on the film. This is a key advantage, as it simplifies the fabrication process and makes it easier to integrate the sensors into practical gas-sensing devices without the need for nanostructure transfer or intricate setups. Scanning electron microscopy (SEM) reveals the porous structure and nanowire formation, while X-ray diffraction (XRD) confirms the presence of the NiO phase. As a preliminary investigation, the gas-sensing properties of NiO films with varying thicknesses were evaluated at different operating temperatures. The results indicate that thinner layers exhibit superior performances. Gas measurements confirm the p-type nature of the NiO samples, with sensors showing high responsiveness and selectivity toward NO₂ at an optimal temperature of 200 °C. However, incomplete recovery is observed due to the high binding energy of NO₂ molecules. At higher temperatures, sufficient activation energy enables a full sensor recovery but with reduced response. The paper discusses the adsorption–desorption reaction mechanisms on the NiO surface, examines how moisture impacts the enhanced responsiveness of Pt-NiO (2700%) and Au-NiO (400%) sensors, and highlights the successful fabrication of NiO nanowires through a simple and cost-effective method, presenting a promising alternative to more complex approaches. Full article

Enhancing the performance of organic solar cells (OSCs) is essential for achieving sustainability in energy production. This study presents an innovative strategy that involves fine-tuning the thickness of the bulk heterojunction (BHJ) photoactive layer at the nanoscale to improve efficiency. The organic blend D18:L8-BO is utilized to capture a wide range of photons while addressing the challenge of minimizing optical losses from low-energy photons. The research incorporates SnO₂ and ZnO as electron transport layers (ETLs), with PMMA functioning as a hole transport layer (HTL). A comprehensive analysis of photon absorption, charge carrier generation, localized energy fluctuations, and thermal stability reveals their critical role in enhancing the efficiency of D18:L8-BO active films. Notably, introducing SnO₂ as an ETL significantly decreased losses and modified localized energy, achieving an impressive efficiency of 19.85% at an optimized blend thickness of 50 nm with low voltage loss (ΔV_oc) of 0.4 V within a J_sc of 28 mA cm⁻² by performing an optoelectronic simulation employing “Oghma-Nano 8.1.015” software. In addition, the SnO₂-based structure conserved 88% of the PCE at 350 K compared to room temperature PCE, which describes the high thermal stability of this structure. These results demonstrate the potential of this methodology in improving the performance of OSCs. Full article