Search Results (11,730)

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

The liquid-core anti-resonant fiber (LCARF) has emerged as a versatile platform for applications in nonlinear photonics, biological sensing, and other domains. In this study, a systematic and comprehensive analysis of LCARF was conducted via the finite element method to evaluate its performance across a wavelength range of 400–1200 nm. This included an assessment of the effects of structural parameters such as capillary wall thickness and the ratio of cladding tube diameter to core diameter on confinement loss and effective refractive index. The results reveal that the proposed core-only-filled approach significantly reduces the confinement loss compared to the conventional fully filled approach, thus facilitating signal transmission. Furthermore, the optimization of geometrical parameters greatly improves the single-mode characteristics of LCARFs. This work establishes a robust theoretical framework and provides valuable support for enhancing the LCARF applications in optofluidics, thereby contributing to the evolution of specialty fiber technologies. Full article

This review paper presents a comprehensive analysis of electroluminescence (EL) imaging techniques for photovoltaic (PV) module diagnostics, focusing on advancements from conventional indoor imaging to outdoor and daylight EL imaging. It examines key challenges, including ambient light interference and environmental variability, and highlights innovations such as infrared-sensitive indium gallium arsenide (InGaAs) cameras, optical filtering, and periodic current modulation to enhance defect detection. The review also explores the role of artificial intelligence (AI)-driven methodologies, including deep learning and generative adversarial networks (GANs), in automating defect classification and performance assessment. Additionally, the emergence of drone-based EL imaging has facilitated large-scale PV inspections with improved efficiency. By synthesizing recent advancements, this paper underscores the critical role of EL imaging in ensuring PV module reliability, optimizing performance, and supporting the long-term sustainability of solar energy systems. Full article

This study presents a structurally tunable Au-based solid polymer electrolyte (SPE) membrane electrode with significantly enhanced performance in organic hydrogenation reactions. Compared to a Pt-based counterpart, the Au-based electrode achieved a 277% increase in cyclohexane yield and a 4.8% reduction in hydrogen evolution during cyclohexene hydrogenation, demonstrating superior catalytic selectivity and energy efficiency. The improved performance is attributed to synergistic optimization of the electrode’s nanostructure and electronic properties. The Au-based electrode exhibited a 215% increase in specific surface area (SSA) relative to its initial state, along with a markedly enhanced electrochemical active surface area (ECSA). These enhancements stem from its mesoporous architecture, lattice contraction, and high density of zero-dimensional defects. X-ray photoelectron spectroscopy (XPS) revealed a negative shift in Au4f binding energy, a positive shift in Ni⁰ peaks, and an increased concentration of oxygen vacancies (Ov), indicating favorable modulation of the surface electronic structure. This reconstruction promotes H* adsorption and accelerates the hydrogenation reaction, serving as a key mechanism for catalytic enhancement. The core innovation of this work lies in the coordinated engineering of nanoscale structure and surface electronic states, enabling concurrent improvements in reaction rate, selectivity, and energy efficiency. These findings offer valuable guidance for designing noble metal-based membrane electrodes in advanced hydrogen energy conversion and storage systems. Full article

Human mesenchymal stem cells (hMSCs) are widely used in regenerative medicine, but large-scale in vitro expansion alters their function, impacting proliferation and differentiation potential. Currently, a predictive marker to assess these changes is lacking. Here, we used dielectrophoresis (DEP) to characterize the electrical phenotype of hMSCs derived from bone marrow (BM), adipose tissue (AT), and umbilical cord (UC) as they aged in vitro from passage 4 (P4) to passage 9 (P9). The electrical phenotype was defined by the DEP spectra, membrane capacitance, and cytoplasm conductivity. Cell morphology and size, growth characteristics, adipogenic differentiation potential, and osteogenic differentiation potential were assessed alongside label-free biomarker membrane capacitance and cytoplasm conductivity. Differentiation was confirmed by histological staining and RT-qPCR. All hMSCs exhibited typical morphology, though cell size varied, with UC-hMSCs displaying the largest variability across all size metrics. Growth analysis revealed that UC-hMSCs proliferated the fastest. The electrical phenotype varied with cell source and in vitro age, with high passage hMSCs showing noticeable shifts in DEP spectra, membrane capacitance, and cytoplasm conductivity. Correlation analysis revealed that population doubling level (PDL) correlated with membrane capacitance and cytoplasm conductivity, indicating PDL as a more precise marker of in vitro aging than passage number. Additionally, we demonstrate that membrane capacitance correlates with the osteogenic marker COL1A1 and that cytoplasm conductivity correlates with the adipogenic markers ADIPOQ and FABP4, suggesting that DEP-derived electrical properties serve as label-free biomarkers of differentiation potential. While DEP has previously been applied to BM-hMSCs and AT-hMSCs, and more recently to UC-hMSCs, few studies have provided a direct comparison across all three sources or tracked changes across continuous expansion. These findings underscore the utility of DEP as a label-free approach for assessing hMSC aging and function, offering practical applications for optimizing stem cell expansion and stem cell banking in clinical settings. Full article

This article reviews the properties and formation process of interface traps in MOS and linear bipolar devices. Transistors are the core components of modern electronic devices, and their performance and reliability directly affect the performance of the entire system. In radiation environments, the emergence and evolution of interface traps severely impacts the functionality of transistors, being a significant factor in device failure. However, our understanding of the properties and formation processes of interface traps is still limited. Therefore, research on interface traps is of great theoretical and practical significance. This paper focuses on studying the radiation response patterns of transistor interface traps. By reviewing relevant literature and research findings from both domestic and international sources, this review provides a detailed overview of the current state of research on the transformation of interface traps and the annealing processes that occur during the irradiation of microelectronic devices. Finally, based on this foundation, this paper discusses the current state of simulation research methods for interface traps. Through an in-depth exploration of the formation mechanisms of interface traps and their role in transistor performance, this study aims to provide guidance for device design, radiation hardening, and reliability assessment, and ensure the reliability and stability of devices in radiation environments. Full article

This paper focuses on the modeling challenges of a multi-cell heterojunction bipolar transistor (HBT) used in radio frequency (RF) power amplifiers and proposes an innovative linear small-signal modeling method. Based on devices with an emitter size of 3 μm × 40 μm × 2–6 (emitter width × emitter length × emitter index-cell number), an equivalent circuit model including peripheral parasitic parameters is constructed by analyzing device layout characteristics in response to additional parasitic effects introduced by the multi-cell structure. A step-by-step parameter extraction method is used, with particular attention paid to the correction of saturated current parameters, temperature coefficients, thermal resistance correction, and the optimization of junction capacitance parameters based on the capacitance ratio relationship. After the extraction of parasitic parameters, the input and output reflection coefficient errors of the model under zero-bias conditions are below 1.66% in the 0.7–25 GHz frequency band. The accuracy of this model is significantly improved compared to the directly parallel single-cell model. The power simulation results match the measured results very well at frequencies of 2.6 GHz and 3.5 GHz. This modeling method significantly improves the model accuracy of multi-cell HBT devices in RF circuit design and provides an effective tool for high-power amplifier optimization. Full article

With the growing demand for high-performance computing (HPC), artificial intelligence (AI), and data communication and storage, new chip technologies have emerged, following Moore’s Law, over the past few decades. As we enter the post-Moore era, transistor dimensions are approaching their physical limits. Advanced packaging technologies, such as 3D chiplets hetero-integration and co-packaged optics (CPO), have become crucial for further improving system performance. Currently, most solutions rely on silicon-based technologies, which alleviate some challenges but still face issues such as warpage, bumps’ reliability, through-silicon vias’ (TSVs) and redistribution layers’ (RDLs) reliability, and thermal dissipation, etc. Glass, with its superior mechanical, thermal, electrical, and optical properties, is emerging as a promising material to address these challenges, particularly with the development of femtosecond laser technology. This paper discusses the evolution of both conventional and advanced packaging technologies and outlines future directions for design, fabrication, and packaging using glass substrates and femtosecond laser processing. Full article

This paper proposes an improved parameter extraction optimization algorithm for radio frequency (RF) devices. The algorithm integrates parameter classification and correction, gradient-based performance handling, bias-aware updates, and group-based optimization strategies, achieving enhanced optimization accuracy, accelerated convergence, and improved stability. It effectively addresses the limitations of deterministic algorithms in RF device parameter extraction optimization, such as low efficiency, sensitivity to initial values, and unstable convergence. To validate the algorithm’s effectiveness, a Ka-band filter performance curve fitting case study was conducted. By comparing simulated curves with optimized fitted curves, the advantages of the algorithm in terms of optimization efficiency, accuracy, and convergence stability were demonstrated. Experimental results show that, compared to traditional optimization algorithms, the proposed method significantly improves curve fitting accuracy, computational efficiency, and stability, highlighting its application value in RF device parameter extraction. Full article

SiC_f/SiC ceramic matrix composite (CMC), a hard and brittle material, faces significant challenges in efficient and high-quality processing of small-sized shapes. To address these challenges, the nanosecond laser was used to process micro-holes in the SiC_f/SiC CMC using a two-step drilling method, including laser pre-drilling in air and laser final-drilling with a water jet. The results of the single-parameter variation and optimized orthogonal experiments reveal that the optimal parameters for laser pre-drilling in air to process micro-holes are as follows: 1000 processing cycles, 0.7 mJ single-pulse energy, −4 mm defocus, 15 kHz pulse-repetition frequency, and 85% overlap rate. With these settings, a micro-hole with an entrance diameter of 343 μm and a taper angle of 1.19° can be processed in 100 s, demonstrating high processing efficiency. However, the entrance region exhibits spattering slags with oxidation, while the sidewall is covered by the recast layer with a wrinkled morphology and attached oxides. These effects are primarily attributed to the presence of oxygen, which enhances processing efficiency but promotes oxidation. For the laser final-drilling with a water jet, the balanced parameters for micro-hole processing are as follows: 2000 processing cycles, 0.6 mJ single-pulse energy, −4 mm defocus, 10 kHz pulse-repetition frequency, 85% overlap rate, and a 4.03 m/s water jet velocity. Using these parameters, the pre-drilled micro-hole can be finally processed in 96 s, yielding an entrance diameter of 423 μm and a taper angle of 0.36°. Due to the effective elimination of spattering slags and oxides by the water jet, the final micro-hole exhibits a clean sidewall with microgrooves, indicating high-quality micro-hole processing. The sidewall morphology could be ascribed to the different physical properties of SiC fiber and matrix, with steam explosion and cavitation erosion. This two-step laser drilling may provide new insights into the high-quality and efficient processing of SiC_f/SiC CMC with small-sized holes. Full article

Scaffolds play a crucial role in tissue engineering as regenerative templates. Fabricating scaffolds with good biocompatibility and appropriate mechanical properties remains a major challenge in this field. This study proposes a method for preparing multi-material scaffolds, enabling the 3D printing of collagen and thermoplastic elastomers at room temperature. Addressing the previous challenges such as the poor printability of pure collagen and the difficulty of maintaining structural integrity during multilayer printing, this research improved the printability of collagen by optimizing its concentration and pH value and completed the large-span printing of thermoplastic elastomer using a precise temperature-control system. The developed hybrid scaffold has an interconnected porous structure, which can support the adhesion and proliferation of fibroblasts. The scaffolds were further treated with different post-treatment methods, and it was proven that the neutralized and cross-linked collagen scaffold, which has both nano-fibers and a certain rigidity, can better support the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). The research results show that the collagen thermoplastic elastomer hybrid scaffold has significant clinical application potential in soft tissue and hard tissue regeneration, providing a versatile solution to meet the diverse needs of tissue engineering. Full article

The high input/output demands of memory packages require precise trace width and spacing, posing challenges for contemporary package design. Substrate copper trace cracks are a major reliability issue during temperature cycling tests (TCTs). This study offers a detailed analysis of copper trace crack mechanisms through experimental observations, material characterization, and numerical simulations. Common failure modes of trace cracks are identified from experimental data, pinpointing initiation sites and propagation paths. Young’s modulus of copper foil samples is assessed using four testing methods, revealing consistent trends across samples from different substrate suppliers. Sample A with higher E/H values tested via nanoindentation correlated with lower failure rates in the experiment. Stress–strain testing on copper foil was successfully performed at the lower TCT temperature limit of −65 °C, providing vital input for finite element (FE) models. The simulations show strong alignment with trace crack locations under different failure modes. The impact of copper trace width and material properties is illustrated in numerical models by comparing variations in plastic strain responses, which show differences of up to 40% and 30%, respectively. The simulation design of the experiments (DOE) indicates that high-strength solder resist (SR) can significantly enhance temperature cycling performance by reducing SR and copper trace stress and strain by up to 75%. The accumulation of plastic strain in copper traces is predicted to increase up to four times when SR breaks at the crack location, underscoring the importance of SR in copper trace reliability. Full article

Tantalum metal and tantalum oxide thin films are commonly used in semiconductor devices, protective coatings, and biomedical implants. However, there is limited information on their nanotribological behavior and small-scale mechanical properties. This study characterized the chemical, mechanical, and tribological properties of as-deposited and 400 °C annealed β-Ta thin films using nanoindentation and atomic force microscope (AFM)-based nanoscale friction and wear tests. X-ray photoelectron spectroscopy (XPS) results revealed that a thermally grown Ta oxide layer forms on the surface of Ta film after being annealed at 400 °C. The nanoindentation data indicated an increase in both the hardness and elastic modulus in the heat-treated sample compared to the as-deposited Ta film (13.1 ± 1.3 GPa vs. 12.0 ± 1.4 GPa for hardness) and (213.1 ± 12.7 GPa vs. 175.2 ± 12.3 GPa for elastic modulus). Our nanotribological results show that the friction increased and wear resistance decreased on the surface of the annealed sample compared to the as-deposited Ta film. This discrepancy may be caused by the oxidation of Ta on the film surface, which induces residual compressive stresses in the film and degrades its wear resistance. Our results highlight the influence of thermal annealing and oxidation on nanotribological behavior and small-scale mechanical properties of Ta thin films. Full article

The development of micro- and nano-fabrication technologies has greatly advanced single-cell and spatial omics technologies. With the advantages of integration and compartmentalization, microfluidic chips are capable of generating high-throughput parallel reaction systems for single-cell screening and analysis. As omics technologies improve, microfluidic chips can now integrate promising transcriptomics technologies, providing new insights from molecular characterization for tissue gene expression profiles and further revealing the static and even dynamic processes of tissues in homeostasis and disease. Here, we survey the current landscape of microfluidic methods in the field of single-cell and spatial multi-omics, as well as assessing their relative advantages and limitations. We highlight how microfluidics has been adapted and improved to provide new insights into multi-omics over the past decade. Last, we emphasize the contributions of microfluidic-based omics methods in development, neuroscience, and disease mechanisms, as well as further revealing some perspectives for technological advances in translational and clinical medicine. Full article

Fiber extractors, as process-intensified equipment, facilitate many applications, such as the purification of oils. The development of high-fidelity computational models is crucial to optimize the design. However, simulating microscale flows around tens of thousands of microfiber arrays is computationally unfeasible. Thus, it is necessary to identify smaller elements, consisting of only a few fibers, that can represent flow within massively arrayed fiber extractors. This study employed computational fluid dynamics to investigate different configurations of four-fiber elements to achieve this aim. Following previous modeling featuring flow around only one fiber, the goal was to understand how variations in inter-fiber distances affect the phase structures of a corn oil/water mixture, the steady-state interfacial surface area per unit of fluid volume, and the pressure drop along the flow direction. The study explored various total and relative flow rates and contact angles. The research characterized the flow as semi-restricted annular, noting the influence of neighboring fibers on phase complexity. The inter-fiber distance played a crucial role in generating high interfacial areas and reducing pressure. The chaotic nature of the slug interfaces facilitated intermixing between flows along different fibers. Interestingly, the specific interfacial area reached an optimum when the inter-fiber distance was between 10 and 50 μm. Full article