Electronic Materials Letters最新文献

This study investigates the magnetic properties of isotropic sintered magnets based on M-type hexaferrite SrFe₁₂O₁₉, enhanced through multi-cation substitution with Al, Cr, and Mn. M-type hexaferrite samples with the general formula SrFe_{12 − 2x}Al_xCr_xO₁₉ (x = 0–0.3) were synthesized via a solid-state reaction method to investigate the effects of Al–Cr substitution on the structural and magnetic properties. X-ray diffraction (XRD) analysis confirmed the formation of a single-phase M-type hexaferrite with minor traces of Fe₂O₃ in some samples. Magnetic characterization showed that coercivity (H_C) increased while remanent magnetization (4πM_r) decreased with increasing x, exhibiting a typical trade-off behavior. Among the compositions, x = 0.2 exhibited the most balanced magnetic properties. Based on this, further substitutions with Mn, Co, La, and Ce were introduced, and Mn substitution slightly enhanced H_C. Optimization of sintering additives and temperature revealed that the composition SrFe_11.5Mn_0.1Al_0.2Cr_0.2O₁₉, sintered with 1 wt% CaCO₃ + 1 wt% SiO₂ at 1230 °C, exhibited the best performance with 4πM_r = 2207 G and H_C = 5304 Oe. The results demonstrate that simultaneous multi-cation substitution and sintering condition control can significantly enhance the hard-magnetic properties of M-type hexaferrites.

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Lead halide perovskites have significant potential as promising materials for a wide range of optoelectronic applications, including solar cells, light-emitting diodes, and photodetectors, due to their outstanding optical and electrical properties. Despite these remarkable properties, their intrinsic structural and environmental instability remains a major barrier to commercialization, as they are highly susceptible to degradation under heat, light, moisture, and bias. To address these challenges, extensive efforts have been devoted to improving the stability of perovskite materials through ligand engineering. In particular, diverse organic ligands with carefully tailored molecular structures have been developed to passivate surface defects and enhance structural robustness. This review highlights recent progress in ligand engineering strategies, focusing on how the structural design of ligands, specifically the number of functional groups within each ligand and the number of ligands coordinating with the perovskite surface, can effectively suppress degradation pathways and improve device performance. Based on these criteria, ligands are categorized into monodentate, polydentate, and dual-ligand systems. This classification provides a framework for systematically exploring ligand–perovskite interactions, ultimately contributing to the realization of durable, efficient, and commercially viable perovskite-based optoelectronic devices.

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The increasing demand for miniaturized and high-performance integrated circuits requires efficient interposer technologies for advanced semiconductor packaging. In this study, anodic aluminum oxide (AAO) was investigated as a potential interposer substrate owing to its excellent electrical insulation and low dielectric constant. A Pd-TiO₂ ink catalyst was applied to enhance the dielectric performance while suppressing copper ion penetration during the electroless Cu deposition. Compared to conventional Sn-Pd catalysts, the application of Pd-TiO₂ improved the dielectric stability and interfacial reliability. Subsequent Cu electroplating using nitrotetrazolium blue chloride (NTBC) as a leveling additive enabled uniform, void-free through-hole filling while minimizing surface overplating, and demonstrated improved void suppression compared to conventional multi-additive systems. Morphological and electrical characterizations confirmed the effectiveness of this single-additive method. This integrated approach combining Pd-TiO₂ catalysis and NTBC-assisted plating demonstrates a viable route toward AAO-based interposers with enhanced dielectric and metallization properties. These findings support the feasibility of using AAO substrates for next-generation semiconductor packages that require high signal integrity and thermal reliability.

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Comparison of catalyst and additive effects on copper filling in AAO interposers. OM images of Cu deposition using a commercial Sn-Pd catalyst, b Pd-TiO₂ catalyst, c NTBC-based single-additive filling after 64 h, and d three-additive filling after 9 h.

This study investigates the impact of sequential exfoliation on the structural, electrical, and electromagnetic interference (EMI) shielding properties of NbSe₂ thin films. Sequential exfoliation yields two distinct films: the 1st, derived from the initial exfoliation, and the 2nd, obtained from further exfoliation of the residual material. Comparative analysis reveals that the 2nd film significantly enhanced total shielding effectiveness in the 8.2–12.4 GHz range, primarily due to its superior absorption shielding effectiveness. This enhancement is attributed to forming a highly uniform, laminated two-dimensional structure, which optimizes electrical conductivity and promotes effective electromagnetic wave dissipation through the skin effect. In contrast, the 1st film contains structural defects and residual oxides, which disrupt conductive pathways and reduce overall shielding efficiency. The denser morphology of the 2nd film facilitates repeated internal reflections, leading to greater energy absorption, whereas the irregular structure of the 1st film limits absorption efficiency.

This study demonstrates the X-ray-activated near-infrared persistent luminescence in Li₂Ge₇O₁₅:Cr³⁺ phosphors by the high-temperature solid-phase method. The influence of Cr³⁺ doping concentration on the structure, morphology and luminescent characteristics of the synthesized material was systematically investigated through X-ray diffraction (XRD), scanning electron microscopy (SEM), fluorescence spectroscopy, and persistent luminescence spectral analysis. The XRD result showed that the synthesized samples were pure. Under X-ray irradiation, the sample Li₂Ge₇O₁₅:Cr³⁺ exhibited near-infrared persistent luminescence and photo stimulated luminescence. The photoluminescence and afterglow emission peaks were located at 699.8 nm, which was due to the ²E→⁴A₂ of Cr³⁺. The optimal Cr³⁺ doping concentration was determined to be 0.05 %, at which the material demonstrated remarkable persistent luminescence performance. Notably, even if exposed to X-ray irradiation only for 5 s, the sample maintained exceptional near-infrared persistent emission characteristics lasting over 30 minutes. Furthermore, the material exhibited exceptional photostimulated luminescence (PSL) characteristics, with its near-infrared afterglow intensity being remarkably amplified under 980 nm laser irradiation. Thermoluminescence (TL) spectral analysis revealed the existence of multiple discrete trap energy levels within the host matrix, whose activation behavior was dependent on the excitation source. Under X-ray irradiation, the sample generated an additional effective trap level, which was more conducive to storing excitation energy. These results suggested that Li₂Ge₇O₁₅:Cr³⁺ was a potential X-ray-induced near-infrared persistent luminescent material.

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To enhance the memory characteristics of the 2-transistor 0-capacitor (2T0C) DRAM cell, the double-layer (DL) InGaZnO channel was strategically introduced and the active geometry was optimally modulated. The DL channel, fabricated by modulating the oxygen partial pressure during RF sputtering, forms a heterojunction interface that introduces an additional conduction path, thereby significantly enhancing the device performance of the transistor. In memory operations, 2T0C DRAM cell employing the DL configuration exhibited more than twice the write speed, reaching a storage node voltage (V_SN) of 0.8 V within 4 µs, compared to 10 µs for single-layer (SL) counterpart under identical charging conditions. Additionally, the optimal determination of the active geometry in transistors has been demonstrated to enhance charge storage efficiency and minimize V_SN degradation. As a consequence of the enhanced positive-bias temperature stress stability, the DL device exhibited a data retention time of 44.3 s at 80 °C, which is approximately four times longer than that of the SL counterpart (11.5 s) with identical geometry. These findings confirm that the combined implementation of a DL IGZO channel and optimized device geometry provides an effective strategy for enhancing both the performance and reliability of 2T0C DRAM cell architectures.

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Recent developments in emerging memory technologies have increasingly highlighted resistive switching (RS) devices, which offer nonvolatile performance, the potential for random data access, simple fabrication, and a streamlined structural design. Owing to these advantages, researchers are now investigating a variety of materials to realize effective RS properties. This review comprehensively examines the latest progress in RS memory devices, focusing on metal oxides, polymers, bioinspired compounds, and halide perovskites, and elucidating their distinct attributes. By integrating key studies, the discussion links the specialized characteristics of these materials to their applicability in memory devices and evaluates innovative approaches and ultimately underscoring the substantial promise of these emerging technologies. Interdisciplinary research efforts and recent investigations further affirm the remarkable transformative potential of RS devices in next-generation electronics.

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The N-deficient g-C₃N₄/Bi₃TaO₇ composite photocatalyst with upconversion capability was synthesized via electrostatic self-assembly. Under visible light, it achieved 80.7% LVFX degradation efficiency, maintaining 65% performance under long-wavelength illumination. PL characterization demonstrated strong upconversion property, with the sample emitting blue light at 470 nm under 800 nm near-infrared excitation. Electrochemical analysis revealed the material’s band structure and confirmed the formation of a Z-scheme heterojunction. Based on these findings, we propose a degradation mechanism: Nitrogen defect levels act as intermediate states for electron transitions, enabling electrons to reach higher energy levels. This process generates high-energy photons that subsequently activate BTO for photocatalytic reactions.

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Fe–Ni alloy was electroplated on Ti rotating cylinder electrode(RCE) at various conditions, varying rotating speed and bath conditions. The inhibition of Ni reduction increased with rotating speed of the electrode, leading to higher Fe content of deposits. The composition change with rotating speed was more apparent for RCE than stationary planar electrode, however, the trend of compositional change in the thickness direction appeared the same regardless of cathode type. Hydrogen evolution was also promoted with rise of rotating speed, causing more brittle deposits and decrease in current efficiency. To obtain complete Fe–Ni invar film (36–40 wt% Ni) without damage, not only the rotating speed but also the bath composition controlled. The Fe content of deposits increased with concentration of Fe²⁺ in the bath, and the composition of films were within target range except the Fe-richer back side than front side.

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This study proposes a novel strategy to enhance the performance of white light-emitting diodes (WLEDs) by integrating graphitic carbon nitride (g-C₃N₄) as an independent blue emitter into Tb³⁺/Eu³⁺-doped lanthanide metal–organic frameworks (Ln-MOFs). Traditional Ln-MOF-based WLEDs suffer from low luminous efficiency due to the Antenna Effect, which compromises energy transfer between ligands and lanthanide ions. By incorporating g-C₃N₄ with high-concentration Tb³⁺/Eu³⁺-doped Ln-MOFs, the optimized composite material, g-C₃N₄@Tb_0.95Eu_0.05-MOF, demonstrated remarkable improvements in photoluminescence properties. Compared to conventional Gd_0.978Tb_0.02Eu_0.002-MOF, the composite achieved a luminous flux of 1.24 lm, luminous efficacy of 1.66 lm/W, and color rendering index (CRI) of 91.6, representing 10.34-fold, 9.23-fold, and 9.0 enhancements, respectively. Mechanistic studies revealed no energy transfer between g-C₃N₄ and Ln³⁺ ions, enabling stable blue emission from g-C₃N₄ while high-concentration Tb³⁺ and Eu³⁺ ions enhanced green and red emissions. This work provides a promising approach for designing high-performance WLEDs.

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