Journal of Electronic Materials最新文献

This study presents a compact, thermally tunable terahertz metamaterial absorber comprising a patterned vanadium dioxide (VO₂) resonator, a dielectric spacer, and a metallic ground plane. Exploiting the thermally induced insulator–metal phase transition of VO₂, the absorber enables dynamic modulation of absorption from near-zero to unity. In the metallic phase, it exhibits multi-resonant broadband absorption with near-unity peaks at 1.91 THz, 4.40 THz, and 5.26 THz, maintaining absorptivity above 70% across the 1.56–5.47 THz range. The design demonstrates polarization insensitivity and robust performance under oblique incidence up to 45°, confirming its suitability for practical THz applications. To accelerate design optimization, machine learning models including random forest, CatBoost, gradient boosting, and a stacked ensemble were used to predict absorption behavior from geometric parameters. The stacked ensemble achieved the highest predictive accuracy (R² = 0.9979), validating the effectiveness of AI-assisted optimization in metamaterial absorber design.

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This brief communication presents recent advances and emerging opportunities in narrow-bandgap polymeric devices for infrared sensing and energy storage applications. Donor–acceptor polymers with extended conjugation offer spectral tunability and redox stability, properties that are key to improving optoelectronic and electrochemical functions. The resulting devices and demonstrations highlight their potential to enable integrated energy and sensing in future autonomous systems.

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This study investigates the evolution of the thermal and mechanical properties of epoxy resin (EP) composites reinforced with functionalized metal–organic framework (MOF) nanoparticles, specifically UiO-66-NH₂ and UiO-66-(OH)₂, following thermal cycling. The interfacial reinforcement mechanisms of MOFs in EP were further elucidated by molecular dynamics simulations. The results show that, after undergoing 100, 200, and 300 thermal cycles, the properties of both UiO-66-NH₂/EP and UiO-66-(OH)₂/EP composites exhibit a monotonic decrease. Nevertheless, they display superior thermal and mechanical performance compared with neat EP, including lower mass loss rates, higher thermal decomposition temperatures, greater residual mass fractions, and enhanced tensile strength. Scanning electron microscopy and Fourier-transform infrared spectroscopy further confirmed that the incorporation of MOFs effectively delays interfacial degradation and inhibits matrix decomposition. Moreover, simulation results reveal that the interface between UiO-66-NH₂ and EP forms numerous covalent bonds via cross-linking reactions between amino and epoxy groups, resulting in a binding energy of approximately 5003 kcal mol⁻¹, which is higher than that of non-cross-linked amino and hydroxyl interfacial systems. In addition, the UiO-66-NH₂/EP interface exhibits the lowest molecular mean square displacement and diffusion coefficient, indicating the highest interfacial compactness and the most restricted molecular chain mobility, thereby achieving the best reinforcement effect. This study elucidates the evolution and mechanisms of the thermal and mechanical properties of MOF/epoxy composites under thermal cycling, providing theoretical support for the design and engineering applications of aerospace materials under space service conditions.

Wide-bandgap (WBG) power modules require robust die attach for high-temperature applications. Ag is attracting attention as a die attach bonding material for WBG power semiconductors due to its advantages such as high thermal/electrical conductivities and high operable temperature. The robustness and reliability of the bonding joint are generally influenced by the chemical and physical state of the surface. Some module manufacturers recommend plasma pre-cleaning of the substrate surface during the Ag sintering process. However, there is insufficient information regarding the effect of plasma pre-cleaning on the sintering characteristics between the Ag plating and Ag powder, and its contribution to improving joint quality. This study investigates the effect of Ar/O₂ plasma pre-cleaning on Ag sintering behavior on the electroplated Ag metallization. We compared three conditions for Cu dies/substrates with electroplated Ag metallization: (1) no cleaning, (2) ethanol ultrasonic cleaning, and (3) ethanol ultrasonic cleaning + Ar/O₂ plasma treatment pressure-assisted Ag sintering. Plasma-treated samples exhibited the highest shear strength (49.38 MPa), a 37.5% increase over non-cleaned samples. The plasma pre-cleaned sample exhibited the best interfacial connection ratio (63.34%) between the Ag sintered layer and Ag metallization and the lowest porosity. These enhancements are attributed to the effective removal of surface contaminants and a significant increase in surface energy, which improved the hydrophilicity of the Ag surface. Ar/O₂ plasma pre-cleaning thus effectively removes contaminants and activates the surface, significantly enhancing the microstructural, mechanical, and thermal properties of Ag sintered joints.

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Because of their intricate composition–processing–property relationships and the high experimental cost of alloy synthesis, shape memory alloys (SMAs), especially ternary Ni-Ti-Hf alloy, remain difficult to predict in terms of their behavior. Efficient materials discovery and alloy design optimization for practical uses depend on the precise classification of SMA and non-SMA compositions. This work offers an interpretable, optimization-driven machine learning (ML) framework to tackle this problem. It combines an adaptive hybrid dandelion optimizer (DETDO) and Bayesian hyperparameter tuning (Optuna) with sophisticated classifiers, such as logistic regression, XGBoost, and CatBoost. To increase generalization and reduce class bias, the dataset was balanced using SMOTEENN resampling and improved with engineered compositional and processing features. With a cross-validation F1-score of 0.9846, a test F1-score of 0.9524, and a test accuracy of 0.9167, the DETDO–XGBoost model outperformed the other models in the test, demonstrating its superior predictive stability. The main factors influencing SMA prediction, according to SHAP interpretability analysis, were Ni atomic percentage, delta_mass, and final-aging duration. This study shows that SMA functionality is defined by a combination of thermomechanical and compositional factors. The suggested framework supports useful developments in automotive, aerospace, and renewable energy applications by offering a quick, scalable, and explicable method for intelligent alloy screening.

The rapid evolution of two-dimensional (2D) materials and heterostructures made with them has unlocked novel opportunities in the design of next-generation optoelectronic and electronic gadgets owing to their exceptional mechanical, electronic, as well as optical characteristics. This review systematically examines the principal fabrication methodologies for 2D heterostructures, including mechanical exfoliation, vacuum filtration, drop casting, and epitaxial growth, with a critical assessment of their scalability, reproducibility, and structural integrity. Special attention is given to deterministic assembly techniques and recent advancements in robotic fabrication for wafer-scale integration. Furthermore, the review explores the broad spectrum of 2D heterostructures technological use in such fields as photodetection, optoelectronics, gas sensing, as well as biosensing. Emphasis is placed on the correlation between band alignment in various heterojunction configurations (type I, II, III, and Z-scheme) and their impact on charge transport, carrier dynamics, and device performance. By offering a comprehensive overview of fabrication strategies and functional implementations, this article aims to guide the progression of 2D material-based heterostructures that provide scalability and high-performance operation for future nanoelectronic and photonic systems.

Hierarchical architecture materials of mesoporous carbon wrapped graphene (MC@G) composite are prepared by a sol-gel coating method, MC@G composites are infiltrated with sulfur to prepare cathode material of lithium-sulfur batteries (Li-S) with high discharge capacity at low current. The MC@G was synthesized using graphene as conductive base material and mesoporous carbon shell wrapped on the surface of graphene as a matrix for loading sulfur, which results in high utilization of active material at low current. The hierarchical architecture of MC@G carbon/carbon nanocomposites forms an effective conducting base material for electron transport in electrode material, which significantly improves the electronic conductivity of cathode material and utilization of active material. Taking advantage of the structure, the S/MC@G cathode material exhibits an initial specific discharge capacity of 1158 mA h g⁻¹ and 1131 mA h g⁻¹ at current of 0.1 C and 0.5 C, the S/MC@G cathode material exhibits higher capacity retention and rate performance than S/rGO cathode material. We believe that the hierarchical mesoporous architecture of MC@G can also be applicable for designing some other electrode materials for energy storage.

This study conducted a systematic investigation on the shear strength and microstructural evolution of Cu/Sn-58Bi/microporous-Cu/Sn-58Bi/Cu composite solder joints subjected to varied bonding parameters and subsequent isothermal aging at 120°C for durations extending to 60 days. The bonding process was executed using a magnetically agitated reflow platform. The joint mechanical properties were evaluated through shear strength testing and microstructural evolution observed by scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS). The results demonstrate that the shear strength of the composite joints peaked at 73 MPa under a bonding temperature of 250°C and a bonding time of 30 s. However, extending the bonding time to 90 s at 250°C induced excessive coarsening of the brittle Bi phase and void formation, resulting in diminished shear strength of 66.7 MPa. During thermal aging, the shear strength exhibited an initial decrease followed by a subsequent recovery. This recovery is primarily associated with the refinement of Bi-rich phases and phase segregation, which lead to the redistribution of internal stress and the temporary stabilization of the microstructure. These observations substantiate the feasibility of fabricating high-performance joints under ambient conditions. These findings provide critical engineering insights for optimizing processing parameters and controlling microstructure to enhance the reliability of high-temperature packaging in third-generation semiconductor devices and power electronics.

Polymeric melon, a heptazine-based carbon nitride, has attracted increasing attention as a sustainable metal-free semiconductor for electronic, optoelectronic, and energy storage applications. Yet, its fundamental optical and electronic characteristics remain debated, particularly regarding the intrinsic nature of photon absorption and the energetic positions of trap states. Here, a unified analytical framework combining Tauc analysis, Jacobian-transformed photoluminescence spectroscopy, and first-principles calculations is employed to clarify the transition mechanism and trap-state energetics in melon nanoparticles. The results reveal that photon absorption in melon arises from both an indirect and direct electronic transition depending on the selection of precursor monomers, and that shallow trap states, located near the conduction band, play a dominant role in carrier recombination dynamics. These findings reconcile longstanding inconsistencies in reported bandgaps and provide a reliable basis for interpreting optical excitation and charge-transport behavior. This integrated approach advances fundamental understanding of charge-carrier dynamics in polymeric melon and provides a broadly applicable strategy for evaluating optoelectronic processes in polymer semiconductors and related nanomaterials.