Electronic Materials Letters最新文献

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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Alq₃ exists in five crystalline phases, with the δ-phase offering excellent charge transport characteristics owing to its minimal π-orbital overlap and short intermolecular binding distance. Previously, the purification of Alq₃ to obtain this specific phase was achieved using ionic liquids instead of sublimation methods. By controlling concentration and temperature, high-purity δ-phase Alq₃ could be obtained. In this study, the effectiveness of purifying Alq₃ using ionic liquids was examined not through high-performance liquid chromatography measurements but by fabricating and characterizing organic light-emitting devices (OLEDs) to assess improvements in purity and mobility. I–V–L measurements of the fabricated devices revealed a decrease in threshold voltage, an increase in maximum luminance, and a reduction in sub-threshold swing after purification. The I–V characteristics confirmed the effectiveness of ionic-liquid-based purification in enhancing material purity. Lastly, electron-only devices were fabricated, and charge mobility was calculated using the Mott–Gurney equation. The simulation and experimental results were compared to clarify the influence of δ-phase Alq₃ purified with ionic liquids on OLED performance.

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The effects of work function and thermal stability of top electrode (TE) materials on the electrical properties of TE/ZrO₂/TiN capacitors for dynamic random-access memory applications were investigated. TEs of Au, Ag, and Al were deposited via thermal evaporation on the atomic-layer-deposited ZrO₂ dielectric layer on a TiN bottom electrode. The high work function of 5.1 eV of Au induced a very stable insulating property, while Ag and Al showed relatively higher leakage current with equivalent dielectric layer fabrication process. To evaluate the interfacial properties between the electrode and dielectric as well as the thermal stability of the electrode, post-metallization annealing (PMA) was performed in an air ambient at 400 °C for 30 min. Ag⁺ ion was diffused into the ZrO₂ layer and Al was oxidized to Al₂O₃ at the interface for Ag and Al TEs, respectively, and severe capacitance degradation occurred. However, Au TE exhibited superior interfacial properties after PMA owing to a curing effect that promoted reducing oxygen vacancies and imperfections near the TE interface, and improved both dielectric and insulating properties.

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