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Research Article

Regular Paper

The direct utilization of steelmaking by-product gases in solid oxide fuel cells (SOFCs) offers a promising pathway to improve energy efficiency and reduce carbon emissions in the steel industry. In this study, a Sr-deficient and Ni-doped double perovskite oxide, Sr1.95Fe1.35Ni0.15Mo0.5O6-δ (SFNM), was investigated as an anode material for direct Linz-Donawitz converter gas (LDG)-fueled SOFCs. A single-phase double perovskite structure was successfully obtained after calcination at 1,200°C for 12 h, while exsolved metallic Ni nanoparticles were generated on the SFNM surface after reduction at 800°C. Electrochemical performance was evaluated using H2, simulated-LDG, and CO/CO2 (85:15) fuels at 800°C. The maximum power densities achieved were 1.23, 0.70, and 0.40 W cm-2 for H2, simulated-LDG, and CO/CO2 fuels, respectively. Although CO-containing fuels exhibited lower opencircuit voltages and power outputs than H2, the SFNM anode maintained stable operation and appreciable performance under direct simulated-LDG utilization. Impedance analysis revealed that the increased polarization resistance in simulated-LDG and CO/CO2 atmospheres was mainly associated with fuel adsorption/desorption and gas diffusion, while interfacial charge-transfer resistance remained relatively small. The superior performance obtained with simulated-LDG compared to the CO/CO2 mixture was attributed to the presence of a small amount of H2, which facilitated anode reaction kinetics. These results demonstrate that SFNM is a promising mixed ionic-electronic conductor anode for the direct electrochemical conversion of CO-rich steelmaking by-product gases into electricity.
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Review Paper

Tutorial Status Report

Wearable temperature sensors are becoming increasingly important for continuous health monitoring, personalized healthcare, and biointegrated electronic systems. However, conventional temperature-sensing platforms often suffer from limited thermal sensitivity, insufficient mechanical compliance, and unstable performance under repeated deformation, making it difficult to detect subtle physiological temperature variations in real time. Here, this tutorial status report presents a fabrication strategy for highly sensitive wearable temperature sensors based on gold-doped crystalline silicon nanomembranes. Gold diffusion into crystalline silicon introduces deep-level impurity states that modulate the Fermi level and shift the freeze-out region toward the physiological temperature range, enabling an ultrahigh negative temperature coefficient of resistance. By integrating the gold-doped silicon nanomembrane with a polyimide-supported ultrathin platform, neutral mechanical plane design, and serpentine mesh interconnects, the resulting device can provide high thermal sensitivity, fast response, conformal skin attachment, and stable operation under mechanical deformation. This fabrication approach is expected to broaden the use of impurity-engineered silicon nanomembranes in next-generation wearable sensors, flexible bioelectronics, and multifunctional healthcare monitoring systems.
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Research Articles

Early Stage Report : Graduate Research

P-type Oxide Thin-Film Transistors Based on Mayer-Rod-Coated CuO Nanowires
Jaeheung Im
J Electr Electron Mater 2026;39(4):426-431.   Published online July 1, 2026
DOI: https://doi.org/10.4313/JEEM.2026.39.4.13
The development of a large-area solution process for CuO nanowires, which are promising p-type thin film transistors (TFT) channel materials, is required. To overcome the limitations of the existing high-vacuum and high-cost deposition process, a large-area Cu nanowire network was formed on the substrate using the Mayer rod coating method, and a CuO channel was implemented by subsequent thermal annealing. Consequently, p-type TFT with an on/off current ratio of 1.4×104 and a field-effect mobility µFE≈10-4 cm2/(V⋅s). was fabricated and optimized. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses showed that the sample annealed at 200°C exhibited an incomplete oxidation state with a mixed Cu/Cu2O phase and a high fraction of M-OH species (58.78%), resulting in a low on/off current ratio (≈1.2). In contrast, annealing at 450°C leads to a CuOdominant phase, where the fraction of lattice oxygen(O1) increases to 31.11% and the oxygen vacancy (VO) component increases to 7.15%, indicating a significant improvement in hole concentration and charge transport. These phase transitions and surface chemical changes are identified as the key mechanisms for the enhanced TFT switching characteristics. The low-cost, large-area Mayer rodbased solution process proposed in this study provides a basic process platform for p-type TFTs applicable to flexible wearables and display technologies and suggests the possibility of commercialization through additional optimization of bias stability in the future.
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Regular Paper

CNN-LSTM-Based Multivariate Anomaly Pattern Detection for Battery Management System
Keon-Sik Hong, Sung-Il Seo
J Electr Electron Mater 2026;39(4):418-425.   Published online July 1, 2026
DOI: https://doi.org/10.4313/JEEM.2026.39.4.12
With the rapid expansion of electric vehicles (EVs) and energy storage systems (ESS), ensuring the operational safety of lithium-ion batteries has become a critical technical challenge. Conventional battery management systems (BMS) primarily rely on threshold-based rule logic, which is limited in detecting coupled anomalies and early-stage degradation patterns. In this study, a deep learning-based framework for multivariate anomaly detection is proposed using BMS sensor data, including voltage, current, temperature, state of charge (SOC), and state of health (SOH). Five representative fault scenarios were defined, including thermal runaway precursors, cell voltage imbalance, SOC inconsistency, internal resistance increase, and communication delay. The proposed CNN-LSTM model was compared with conventional Rule-based methods and machine learning models, including Isolation Forest, Autoencoder, and LSTM. Experimental results show that the proposed model achieved the highest performance, with an F1-score of 0.885, an AUC of 0.94, and a detection delay of 8.1 s. In contrast, the Rule-based method exhibited a significantly higher false negative rate of 42.0%, indicating limitations in detecting complex anomaly patterns. These results demonstrate that the proposed spatiotemporal deep learning approach can significantly improve the accuracy and responsiveness of battery anomaly detection. Furthermore, the proposed method is expected to contribute to enhancing safety, reliability, and predictive diagnostics in next-generation intelligent BMS platforms.
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Early Stage Report: Graduate Research

Magnetically Directed Percolation Networks in Polydopamine-Mediated Carbon Nanotube/Fe3O4 Nanocomposites
Dongyeong Gim, Hyeokju Kwon, Minjeong Ha
J Electr Electron Mater 2026;39(3):288-294.
Published online May 1, 2026
DOI: https://doi.org/10.4313/JEEM.2026.39.3.8
Polymer nanocomposites incorporating inorganic nanofillers have emerged as highly promising electromagnetic interference (EMI) shielding materials, combining mechanical compliance with robust conductive percolation networks. Carbon nanotubes (CNTs) are particularly attractive as conductive fillers because their high aspect ratio facilitates percolation at low loadings. Also, CNTs offer superior mechanical durability under deformation compared to rigid, fracture-prone metal nanowires. For EMI shielding, high electrical conductivity is critical as it enhances both reflection and absorption through efficient charge dissipation and conduction losses. However, achieving highly aligned conductive pathways without degrading the intrinsic electrical properties of CNTs remains a significant challenge. Here, we demonstrate a non-destructive magnetic surface-functionalization and alignment strategy. Using a polydopamine (PDA)-mediated route, pristine multiwalled CNTs are uniformly decorated with Fe3O4 nanoparticles (FMWCNTs). This enables highly effective magnetic field-driven alignment at fields as low as 10 mT, promoting the strategic formation of percolation networks. By optimizing the Fe₃O₄/MWCNT ratio for high saturation magnetization and uniform coverage, the aligned FMWCNTs exhibit significant electrical anisotropy, delivering a 10.7-fold higher electrical conductivity in the parallel configuration compared to the vertical configuration. These findings present a scalable, room-temperature platform for engineering directionally enhanced conductivity in polymer nanocomposites, with broad applicability in advanced EMI shielding, flexible electronics, and advanced packaging technologies.
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Regular Paper

Enhanced Photoluminescence of CsPbBr3 via Improved Optical Transparency of Thermally Treated GaN Nanowires
Kwang Jae Lee, Jungwook Min
J Electr Electron Mater 2026;39(3):272-280.
Published online May 1, 2026
DOI: https://doi.org/10.4313/JEEM.2026.39.3.6
GaN nanowire (NW)-based hybrid structures have attracted attention for optoelectronic applications due to their high surface area and efficient carrier transport. However, the optical transparency of GaN NWs is often limited by unintended residual species accumulated on the surface and in the inter-wire regions, as well as defect-related absorption, leading to reduced light transmission. In this work, we demonstrate that thermal annealing significantly improves the optical transparency of GaN NWs grown on indium tin oxide (ITO)/glass substrates. The transmittance increased from 47.9% to 78.5% at 550 nm after rapid thermal annealing at 800oC for 3 min, while a comparable value (~75.5%) was achieved at 600oC for 5 min. PbBr3 was deposited onto the GaN NWs to form hybrid structures, and temperature-dependent photoluminescence (TDPL) measurements revealed enhanced emission stability with suppressed peak shift and reduced spectral broadening. Arrhenius analysis based on a two-channel model revealed that the activation energy of the dominant non-radiative recombination pathway increased from 62 meV in the as-grown sample to 85 meV after thermal annealing, while its relative contribution remained nearly unchanged. In contrast, the shallow trap-assisted pathway exhibited a similar activation energy of approximately 6 meV in both samples, but its contribution decreased from 0.35 to 0.17 after annealing. As a result, the internal quantum efficiency (IQE) improved from 75.9% to 87.4%. These results show that thermal annealing improves optical transparency by removing residuals and suppresses defect-related recombination, leading to enhanced carrier dynamics and improved optical performance of PbBr3-based hybrid structures.
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Review Papers

Academic Progress Report

Single-Molecule Manipulation Techniques Based on Mechanical, Electrical, and Structural Control
Jeong Hun Shin, Tae Won Nam
J Electr Electron Mater 2026;39(3):247-257.
Published online May 1, 2026
DOI: https://doi.org/10.4313/JEEM.2026.39.3.3
The ability to manipulate and probe biomolecules at the single-molecule level has become an essential approach for understanding molecular interactions, conformational dynamics, and nanoscale transport phenomena. Advances in experimental techniques have enabled precise control of individual molecules with high spatial resolution and piconewton-level force sensitivity. These developments have significantly expanded the capability of studying biomolecular mechanics and dynamics beyond conventional ensemble measurements. A variety of physical strategies have been developed for single-molecule manipulation, including mechanical-force-based approaches, electric-field-driven methods, and nanoscale structural confinement techniques. Mechanical-force-based methods, such as optical tweezers, magnetic tweezers, and atomic force microscopy, enable direct measurement of molecular mechanical responses. Electric-field-based manipulation, represented by dielectrophoresis, allows noncontact control of particles and biomolecules through polarization effects in non-uniform electric fields. In addition, nanopore-based systems employ nanoscale confinement to regulate molecular transport and residence behavior. This review provides an overview of representative single-molecule manipulation techniques based on mechanical, electrical, and structural control and discusses their fundamental principles and implementation strategies.
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Metamaterials-Integrated Triboelectric Nanogenerator Systems
Ahmed Mahfuz Tamim, Youngseo Song, Chang Kyu Jeong
J Electr Electron Mater 2026;39(3):238-246.
Published online May 1, 2026
DOI: https://doi.org/10.4313/JEEM.2026.39.3.2
Metamaterials, as artificially engineered structures with unconventional mechanical and acoustic properties, have recently emerged as a transformative platform for enhancing the capabilities of triboelectric nanogenerator (TENG) systems. Since the invention of TENG devices, extensive efforts have been devoted to improving charge density, output stability, and overall performance. Conventional performance optimization strategies mainly rely on device-level improvements such as surface chemistry modification, microstructuring, and nanopatterning. However, limited emphasis has been given to system-level development of smart self-powered intelligent systems. The integration of metamaterials into TENG devices opens a new era by enabling frequency-selective localization, mechanical impedance matching, and controllable deformation pathways. These engineered mechanical structures not only improve energy harvesting efficiency but also introduce new functionalities into the system. This review systematically summarizes recent advances in metamaterial-integrated TENG systems across four major application domains: (i) energy harvesting, (ii) acoustic telecommunication and acoustic-to-electric conversion, (iii) self-powered sensing, and (iv) vibration suppression and monitoring. Overall, the integration of metamaterials into TENG systems will pave the way for next-generation sustainable, intelligent, self-powered devices with diverse functionalities.
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Recent Progress in Relaxor-State Design of BNT-Based Ceramics for High-Efficiency Energy-Storage Capacitors
Yeseul Lim, Geon-Tae Hwang
J Electr Electron Mater 2026;39(3):225-237.
Published online May 1, 2026
DOI: https://doi.org/10.4313/JEEM.2026.39.3.1
Lead-free bismuth sodium titanate (BNT)-based ceramics have attracted strong attention as environmentally benign dielectric materials for high-efficiency electrostatic energy-storage capacitors. A key challenge is that pristine BNT typically exhibits large hysteresis, high remnant polarization, and limited dielectric reliability, which restrict recoverable energy storage and efficiency under practical electric fields. Here, we present a focused mini-review of recent studies to clarify how composition design, phase boundary tuning, defect chemistry, and microstructural control collectively enable slim or pinched polarization-electric field (P-E) behavior and improved energy-storage functionality in BNT-related bulk ceramics. The reviewed outcomes consistently show that stabilizing relaxor states governed by polar nanoregions (PNRs), often via solid-solution engineering and secondary relaxor/antiferroelectric-like incorporation, suppresses irreversible switching and reduces hysteresis loss, while densification and grain-size control enhance electrical homogeneity and breakdown strength. In addition, defect-mediated tuning of oxygen vacancy-related complexes is highlighted as an independent lever to control relaxor ergodicity and polarization reversibility, providing a complementary route to slim-loop optimization. These insights are expected to guide integrated design strategies that couple phase/relaxor-state engineering with defect and microstructure optimization, accelerating the development of reliable, temperature-robust, lead-free dielectric capacitors based on BNT-related ceramics.
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Recent Progress on Transition Metal-Based Oxygen Evolution Reaction Electrocatalysts in Alkaline Medium
Gyeongbae Park, Da-un Han, Won Rae Kim, Seung-min Yang
J Electr Electron Mater 2026;39(2):129-146.
Published online March 1, 2026
DOI: https://doi.org/10.4313/JEEM.2026.39.2.3
Electrochemical water splitting has emerged as a pivotal technology for green hydrogen production, offering a viable pathway toward a sustainable energy future. Among various electrolysis systems, Anion exchange membrane water electrolysis is particularly noteworthy as a cost-effective solution capable of operating under the fluctuating power inputs typical of renewable energy sources. However, the overall efficiency of water splitting is fundamentally limited by the oxygen evolution reaction, which exhibits sluggish kinetics compared to the hydrogen evolution reaction. While IrO2 and RuO2 serve as current benchmarks, their scarcity and high cost necessitate the development of earth-abundant alternatives. This review provides a comprehensive overview of fundamental OER mechanisms including the adsorbate evolution mechanism, lattice oxygen mechanism, and oxide path mechanism while highlighting how new pathways can circumvent traditional scaling relations. We discuss recent advancements in transition metal-based electrocatalysts, encompassing oxides, hydroxides, chalcogenides, phosphides, nitrides, and carbides, with a focus on innovative design strategies such as defect engineering, heteroatom doping, and heterostructure construction. This paper concludes by addressing current challenges and offering perspectives on future directions for the development of highly efficient and economically viable oxygen evolution electrocatalysts for large-scale applications.
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Fabrication and Analysis of Electrical and Mechanical Properties of CNF Composite Insulation Papers
Seohee Hwang, Chanyong Lee, Hangoo Cho, Jaehyeong Lee
J Electr Electron Mater 2026;39(1):14-18.   Published online January 1, 2026
DOI: https://doi.org/10.4313/JEEM.2026.39.1.2
Cellulose nanofiber (CNF) has attracted significant attention as a next-generation insulating material due to its ecofriendly nature and outstanding functionalities. However, conventional kraft insulation paper suffers from limited dielectric breakdown strength and long-term reliability under high-voltage conditions, highlighting the need for alternative materials. In this study, kraft pulp was combined with five types of CNFs (A, B, C: wood-based / D, E: non-wood-based) to fabricate composite insulation papers, and their electrical and mechanical properties were systematically evaluated. The results showed that CNF incorporation generally enhanced density and tensile strength, while certain types contributed to lowering dielectric constant and improving breakdown strength. Among the wood-based CNFs, type C exhibited the most balanced performance in terms of dielectric stability and mechanical reinforcement. Among the non-wood-based CNFs, type E demonstrated notable improvements in structural compactness and tensile strength, suggesting favorable reliability. Therefore, this study identifies CNF C among wood-based types and CNF E among non-wood-based types as the most promising candidates for insulation performance enhancement, suggesting their applicability as next-generation insulating materials for power equipment and ecofriendly electronic devices.
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Investigation of PAN-based Nanofiber Air Filters for Effective Carbon Dioxide Adsorption
Haebin Park, Jungwoo Hong, Soyoung Moon, Taejoon Lee, Dongwon Kang, Kyungtaek Min
J Electr Electron Mater 2026;39(1):88-93.   Published online January 1, 2026
DOI: https://doi.org/10.4313/JEEM.2026.39.1.11
The continuous rise of atmospheric carbon dioxide (CO₂) emissions highlights the urgent need for sustainable air purification technologies. Current Direct Air Capture (DAC) filters often rely on toxic amines, which limit long-term stability and safe application. Here, we report a non-toxic PAN-based nanofiber air filter fabricated by electrospinning and urea-assisted carbonization. Structural analyses confirmed the introduction of nitrogen functionalities that enhanced CO₂ affinity, while SEM and FT-IR revealed graphitic carbon formation. In air-chamber tests, the optimized carbonized nanofiber reduced CO₂ concentration from 25,000 ppm to 2,000 ppm, a level generally regarded as acceptable for indoor environments, while simultaneously removing over 95% of PM10, PM2.5, and PM0.1 particulates. This dual functionality, combined with facile fabrication and material safety, demonstrates strong potential for PAN-derived carbon nanofiber membranes in DAC systems and eco-friendly air purification devices. These findings suggest a viable pathway toward scalable, sustainable air-filter technologies for carbon-neutral applications.
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e investigated the effects of post-annealing in vacuum, nitrogen, and hydrogen atmospheres on the structural, electrical, and optical properties of 600 nm thick Al-doped ZnO (ZnO:Al) thin films deposited by RF magnetron sputtering at room temperature. Post-annealing in hydrogen atmosphere at 400℃ for 1 hour showed the most significant improvement in electrical properties. Resistivity decreased from 9.11×10⁻³ to 1.4×10⁻³ Ω·cm, electron mobility increased from 4.11 to 18.23 cm²/V·s, and electron carrier concentration increased from 1.63×10²⁰ to 4.85×10²⁰ cm⁻³. In contrast, post-annealing in vacuum and nitrogen atmospheres resulted in degraded electrical properties due to oxygen and nitrogen chemisorption at grain boundaries. The enhancement in hydrogen-annealed films was attributed to the formation of additional oxygen vacancies and desorption of adsorbed oxygen species from grain boundaries. All films maintained excellent optical transparency of 80-90% in the visible range. The optical bandgap exhibited a blue-shift from 3.365 eV to 3.624 eV due to the Burstein-Moss effect induced by the increased electron carrier concentration. These results confirmed that hydrogen atmosphere post-annealing is the most effective method for enhancing the electrical conductivity of ZnO:Al thin films while maintaining high optical transparency.
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Optimization of High-Precision Nozzle-Printing Processes and Process Parameters Analysis
Chanyeong Jung, Jeonggyo Kwon, Sunyoung Sohn
J Electr Electron Mater 2025;38(6):617-628.   Published online November 1, 2025
DOI: https://doi.org/10.4313/JEEM.2025.38.6.3
Nozzle-printing dispensers, which utilize air pulsation as a dispensing principle, operate by transmitting air pressure to the liquid to push a constant amount of liquid. Nozzle printers have the advantage of precisely controlling energy based on liquid properties, such as viscosity and surface tension, enabling the precise application of liquid at specific locations and quantities. This study introduces a printing process sequence using a nozzle printer equipped with a high-resolution vision alignment system. It compares printing patterns according to key process variables (jet pressure, tip height, and travel speed) that affect coating quality. Experimental results showed that a coating standard deviation of 2.14 μm was achieved at a moving speed of 20 mm/s and a nozzle height of 0.2 mm, resulting in the most stable and uniform coating quality. Through these experiments, optimal conditions were identified based on factors such as coating width, uniformity, and presence of discontinuity, and the effects of these conditions on the precision manufacturing process are discussed.
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Study on Warpage Measurement of Ceramic Thin Plates Using Non-Contact Methods
Hyo-dong Lee, Ye-won Moon, Ji-hui Oh, Jin-ae Kim, Jun-woo Lee, Sang-mo Koo, Dong-won Lee, Jong-min Oh
J Electr Electron Mater 2025;38(6):696-703.   Published online November 1, 2025
DOI: https://doi.org/10.4313/JEEM.2025.38.6.14
Ceramic thin plates are widely utilized in various advanced technologies, such as fuel cells and heat dissipation substrates, due to their high mechanical strength and thermal conductivity. However, the trend of thinning ceramic plates increases warpage, which can critically affect product quality and reliability. Therefore, understanding and accurately measuring this warpage has become increasingly important. In this study, a non-contact measurement method, the light sectioning technique, was applied to measure the warpage of thin ceramic plates with a half-cell (anode/electrolyte) structure for solid oxide fuel cells (SOFC) by varying their area and thickness. The relationship between the physical properties of the thin plates and the warpage was analyzed. Additionally, a comparative analysis was conducted to evaluate warpage errors caused by compressive loads during the traditional contact measurement process. Finally, to verify the reliability of the non-contact measurement method, four types of non-contact measurement techniques - light sectioning technique, laser displacement measurement, optical confocal technique, and white-light interferometry technique - were used to compare warpage data by orientation. The results were also compared with those from contact measurement methods to analyze the average warpage values. Through this, the superiority and high reliability of the non-contact measurement method were demonstrated.
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Enhanced Ambipolarity of Semiconducting Carbon Nanotubes by Thermal Annealing for High-Performance CMOS-like Circuits
Jeong-min Lee, Ji-yoon Jung, Kang-jun Baeg
J Electr Electron Mater 2025;38(5):530-537.   Published online September 1, 2025
DOI: https://doi.org/10.4313/JEEM.2025.38.5.8
With the advancement of the information society, the demand for highly integrated and multi-functional electronic devices is rapidly increasing. To meet these demands, high-performance transistors with low power consumption, high-speed operating, and mechanical flexibility are essential. Among various candidates, semiconducting single-walled carbon nanotubes (s-SWCNT)-based transistors, which exhibit intrinsically ambipolar characteristics, have emerged as promising components for CMOS-like circuits. In this study, s-SWCNT were selectively dispersed using rr-P3DDT, a thiophene-based conjugated polymer, and filed-effect transistors (FETs) were fabricated by inducting directional alignment for enhanced charge transport through an off-centered spin-coating process. The electrical characteristics of the fabricated s-SWCNT FETs were evaluated under various thermal annealing conditions (100℃, 150℃, 200℃, and 250℃). Off-centered spin-coated and high temperature annealed s- SWCNT FETs exhibited high field-effect mobilities over 5 cm²/Vs in both p-type and n-type operation, along with ideal Vshaped ambipolar transfer curves. These results indicate a significant enhancement in ambipolar performance due to efficient desorption of residual oxygen and water molecules in active channel via high temperature annealing. Furthermore, CMOS-like inverter circuits demonstrated an ideal inversion voltage (VIN = VDD/2) and a high voltage gain of approximately 9.5. These findings highlight the potential of SWCNT-based materials for realizing next-generation flexible electronic circuits that combine high-performance, energy efficiency, and simplified solution-processing.
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A Study on the Development of an Uninterruptible Diagnosis Determination Method for Molded Transformers Using Multiple Diagnosis Sensors
Seok Myung Bae, Yong Moo Chang, Hyo Jin Kim
J Electr Electron Mater 2025;38(5):573-579.   Published online September 1, 2025
DOI: https://doi.org/10.4313/JEEM.2025.38.5.14
With the rapid development of digital technologies such as IoT, AI, and big data, electrical energy consumption is rapidly increasing. Electrical facilities that supply electrical energy are operated with high reliability and stability for end-of-life time. In addition, depending on the type of electrical load that consumes electrical energy in various forms, electrical insulation systems deteriorate due to electrical and thermal stress, which reduces electrical and mechanical insulation strength. Due to such continuous stress and electrical transient phenomena, electrical facilities may experience electrical accidents due to electrical insulation breakdown before the expected design lifetime. In addition, periodic inspections according to related regulations must be conducted to prevent unexpected electrical accidents, but this leads to problems in which the electrical facilities cannot be turned off. Therefore, it is believed that an uninterruptible diagnostic judgment technique that determines compliance with related regulations such as electrical facility technology standards, internal wiring regulations, and inspection regulations without turning off the electrical facilities and at the same time detects abnormal conditions of the facilities early, it is possible to prevent electrical accidents and improve the efficiency of electrical facilities. In this paper, we propose an uninterruptible power diagnosis judgment technique that can prevent or reduce electrical accidents in cast-iron transformers by applying judgment criteria of diagnostic sensors for various types of measurement parameters that can diagnose and evaluate the presence or absence of abnormalities in electrical equipment, including partial discharge, and AI algorithms learned from data of diagnostic sensors.
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Structural and Electrical Properties of (1-x)La0.7Sr0.3MnO₃-xBaTiO₃ Ceramics for Temperature Sensors
Yong-seok Choi, Young-gon Kim, Sung-gap Lee
J Electr Electron Mater 2025;38(4):431-435.   Published online July 1, 2025
DOI: https://doi.org/10.4313/JKEM.2025.38.4.12
The composite specimens of (1-x)(La0.7Sr0.3)MnO₃-xBaTiO₃ (x = 0.05 ~ 0.3) were synthesized using the conventional solid-state reaction method, and the sintering temperature and time were 1,300℃ and 3 hours, respectively. As a result of observing the structural characteristics, the crystal structure of LSMO-BT solid solution was shown in which the rhombohedral LSMO phase and the tetragonal BT phase were separated and distributed, respectively. And fine grains having relatively small and uniformly distributed grains with sizes ranging from approximately 0.4 to 0.5 μm and pores within the specimens were observed. Notably, variations in the BT content did not significantly affect the grain size or porosity distribution, and a relative density of about 90% or more was shown. The resistivity, temperature coefficient of resistance (TCR), and B25/65-value of the 0.7LSMO-0.3BT specimen at room temperature showed the highest values of 1.94 Ω-cm, 0.292 %/℃, and 464 K, respectively. The resistivity behavior of the LSMO-BT composites matched well with the small polaron hopping conduction model.
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Study on Hetero Gate Dielectrics to Reduce Ambipolar Current in Nanosheet Tunneling FETs
A-young Kim, Da-eun Bang, Hyo-jun Park, Tae-hyun Kil, Ju-won Yeon, Moon-kwon Lee, Eui-cheol Yun, Min-woo Kim, Su-jin Jeon, Moon-seok Kim, Jun-young Park
J Electr Electron Mater 2025;38(3):296-301.   Published online May 1, 2025
DOI: https://doi.org/10.4313/JKEM.2025.38.3.9
Aggressive device scaling has severely degraded the switching characteristics of CMOS transistors. This issue has led to the development of tunneling FETs (TFETs) as an alternative. TFETs, with their asymmetric doping of the source and drain regions, offer improved subthreshold swing (SS) compared to conventional MOSFETs. However, despite this advantage, TFETs still suffer from ambipolar current, which increases off-state current (IOFF). This paper introduces an approach to applying hetero gate dielectrics (HGDs) in nanosheet (NS) TFETs to reduce ambipolar current characteristics. The magnitude of the drain electric field is reduced by selectively forming a high-k dielectric near the source region This configuration allows the TFETs to avoid unintended band-to-band tunneling (BTBT) and suppress ambipolar current during the off-state.
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Fabrication and Characterization of Magnetic Field Sensor Based on Fiber Bragg Grating and Terfenol-D Bar
Kwang Taek Kim, Gun Pyo Kim
J Electr Electron Mater 2025;38(3):278-281.   Published online May 1, 2025
DOI: https://doi.org/10.4313/JKEM.2025.38.3.6
We have proposed and demonstrated a fiber optic magnetic field sensor using a FBG (fiber bragg grating) attached on a Terfenol-D bar. The volume of Terfenol-D is changed by the applied magnetic field due to the magnetostriction effect, as a result, the grating period of FBG varies with the intensity of the magnetic field and the Bragg wavelength of FBG is shifted. The temperature sensitivity of the sensor was measured with and without the magnetic field. The temperature sensitivity of the sensor was measured to be 0.02 nm/℃. We observed that the sensitivity of the fabricated device to magnetic field intensity was decreased with the environment temperature.
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A Review on Evaluation of Elastic Modulus Using Nanoindentation
Seo Hyeon Jang, Oh Min Kwon, Si Hyun Park, Hyun Wook Cho, Jong-hyoung Kim
J Electr Electron Mater 2025;38(3):247-253.   Published online May 1, 2025
DOI: https://doi.org/10.4313/JKEM.2025.38.3.2
This review examines the principles, limitations, and recent advancements in elastic modulus measurement using nanoindentation. The importance of accurate contact area prediction is discussed, along with the Oliver-Pharr method and its limitations. The Continuous Stiffness Measurement (CSM) technique is presented as a significant improvement, allowing continuous measurement of mechanical properties throughout the indentation process. For ultra-thin films, the Li and Vlassak method, which incorporates Yu's solution and the concept of effective thickness, is highlighted as a means to correct for substrate effects. Recent developments in artificial neural network-based models for elastic modulus prediction are also explored. These advancements have greatly expanded the applicability of nanoindentation in semiconductor and MEMS device reliability assessment.
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Neuromorphic Characteristics of Sol-Gel AlOx-Based Floating Gate Memory Transistors with Phosphonic Acid Self-Assembled Monolayers
Hee-won Hwang, Sneha Bhise, Young-seok Song, Tae-wook Kim
J Electr Electron Mater 2025;38(3):336-345.   Published online May 1, 2025
DOI: https://doi.org/10.4313/JKEM.2025.38.3.15
Neuromorphic computing, inspired by the biological mechanisms of neural signal transmission, has emerged as a promising technology for efficient and parallel data processing with minimal power consumption. In this study, we developed floating-gate organic thin-film transistors (OTFTs) with self-assembled monolayer (SAM)-based tunneling layers to mimic the characteristics of artificial synapses. The tunneling layers were formed using mixed phosphonic acid SAMs with varying ratios of octadecylphosphonic acid (ODPA) and 12-pentafluorophenoxydodecylphosphonic acid (PFPA). The influence of these ratios on the memory and neuromorphic characteristics of the devices was systematically evaluated. Our results revealed that the ODPA ratio significantly impacts the hysteresis window, with higher ODPA content yielding improved memory characteristics. Conversely, the PFPA : ODPA ratio of 2:1 exhibited the lowest non-linearity (NL = 0.48), demonstrating the potential for highly accurate weight updates in neuromorphic devices. Additionally, pulse width modulation studies showed that a pulse width of 100 ms optimized the linearity and stability of long-term potentiation (LTP) and depression (LTD) characteristics. The combination of sol-gel processed AlOx as a floating-gate layer and tailored SAM-based tunneling layers allowed for precise control of device performance. These findings highlight the importance of molecular engineering in designing SAM layers to balance memory retention and neuromorphic functionality. This study provides a pathway for advancing organic floating-gate transistors as a core component in next-generation neuromorphic computing systems.
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Eco-Friendly Electrically Conductive Adhesives: Silver Optimization for High Performance and Sustainability
Eunae Jo, Chaehwan Jeong
J Electr Electron Mater 2025;38(3):319-323.   Published online May 1, 2025
DOI: https://doi.org/10.4313/JKEM.2025.38.3.12
The growing demand for miniaturized, lightweight, and sustainable electronic devices has intensified the need for advanced bonding materials. Existing electrically conductive adhesives (ECAs) often rely on high silver (Ag) content, resulting in elevated costs and environmental concerns. This study successfully developed a novel ECA with significantly reduced Ag content without compromising essential electrical conductivity and adhesion performance. Experimental results revealed that the optimized ECA demonstrates electrical conductivity comparable to that of commercial products, with notable advantages in cost reduction and eco-friendliness. These advancements position the developed ECA as a promising solution for next-generation electronic manufacturing, contributing to low-carbon technologies and sustainable practices. Future applications could further broaden its use across diverse electronic systems, driving progress in environmentally conscious technologies.
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Research Trends by Dimension in 0D, 2D, and 3D Perovskites
Youngchae Cho, Donghwan Yun, Yunhye Jeong, Gwangyong Shin, Hyesun Shin, Gi-hwan Kim
J Electr Electron Mater 2025;38(2):153-160.   Published online March 1, 2025
DOI: https://doi.org/10.4313/JKEM.2025.38.2.4
Perovskite, which follows the chemical formula ABX3 and exhibits an octahedral structure, is primarily a hybrid of organic and inorganic materials. It can be broadly categorized into three types based on dimensionality: 0D nanocrystals, quasi- 2D, and 3D bulk structures. As a result, it is gaining attention as a next-generation optoelectronic material for applications in light-emitting devices, solar cells, and sensors. This paper provides insights into dimension of perovskites, their respective synthesis methods, and current research trends, thereby offering prospects for advancements in the study of next-generation optoelectronic materials.
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A Review of Fundamentals and Applications in Laser Material Processing
Gyu Been Kim, Chang Byeok Jeong, Hee Yoon Jang, Min Cheol Cheon, Sung Kyu Jang, Seoung-ki Lee
J Electr Electron Mater 2025;38(2):119-131.   Published online March 1, 2025
DOI: https://doi.org/10.4313/JKEM.2025.38.2.1
The laser (LASER), originating from the principle of stimulated emission proposed by Albert Einstein, has been a catalyst for substantial advancements across numerous industrial and scientific domains. Initially confined to research and laboratory applications, the scope of laser technology has expanded rapidly over time. This expansion is primarily due to the laser's unique characteristics, such as high-density energy output and precise beam control, which have facilitated its widespread integration into contemporary industrial practices. Specifically, laser materials processing technology enables the machining of diverse materials, including metals, ceramics, and polymers, in a non-contact manner, thereby achieving high precision without the risk of wear or contamination. As a result, laser processing has become indispensable in fields such as advanced electronics manufacturing, medical device production, aerospace, and the automotive industry. Furthermore, laser materials processing exhibits significant potential for high-precision applications that demand minimal thermal deformation of materials, such as microfabrication and the production of complex geometries. This paper provides a comprehensive examination of the development and necessity of laser processing technology, explores various laser types and their possible applications, and elucidates why laser technology has emerged as a fundamental component of modern manufacturing, alongside its trajectory for future development.
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Fabrication and Evaluation of Thin Film Transistors
Hana Kang, Hayoung Kim, Jaemo Yun, Yoon Kyeung Lee
J Electr Electron Mater 2025;38(1):33-41.   Published online January 1, 2025
DOI: https://doi.org/10.4313/JKEM.2025.38.1.4
In this study, the electrical properties of zinc oxide (ZnO) thin-film transistors (TFTs) based on oxide semiconductors were analyzed. As interest in next-generation transparent and flexible displays grows, ZnO, which offers high field-effect mobility and transparency, has emerged as a promising material to overcome the limitations of amorphous silicon (a-Si)-based TFTs. ZnO has a wide bandgap and optical transparency and can be deposited on various substrates at low temperatures, making it a suitable channel material for future display devices. In this study, ZnO TFTs were fabricated with an inverted staggered structure using a p++ Si wafer coated with SiO2 as the substrate. The ZnO channel layer was deposited by RF magnetron sputtering, and the ITO source/drain electrodes were formed using an e-beam evaporator. The electrical characteristics was evaluated using Keithley 4200A-SCS parameter analyzer. Mobility, On/Off ratio, and subthreshold swing (SS) were calculated from the measurements.
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Recent Advances in Mechano-Electrochemical Energy Harvesting Using Carbon Nanotube
Hyeon Jun Sim, Changsoon Choi
J Electr Electron Mater 2025;38(1):8-20.   Published online January 1, 2025
DOI: https://doi.org/10.4313/JKEM.2025.38.1.2
Energy harvesting technology offers an innovative solution for providing self-sustaining power to wearable and implantable electronic devices. However, traditional energy harvesters face limitations in operating within electrolytic environments or at low motion speeds. To overcome these challenges, a mechano-electrochemical energy harvester using carbon nanotubes has been developed. This technology relies on electrochemical ion movement to induce changes in electrochemical double-layer capacitance, enabling operation within electrolytes and optimizing performance at low deformation speeds. This environmentally friendly and sustainable energy solution is expected to play a crucial role in the advancement of future smart systems and wearable technologies.
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Effect of Interface Structure on the Efficiency Enhancement of Al-PDMS Triboelectric Nanogenerator
Dong-woo Hong, Wan-gon Hong, Seung-hun Kim, Sung-nam Lee
J Electr Electron Mater 2025;38(1):107-112.   Published online January 1, 2025
DOI: https://doi.org/10.4313/JKEM.2025.38.1.15
Recent studies have focused on enhancing the efficiency of triboelectric nanogenerators (TENGs) using aluminum (Al) and polydimethylsiloxane (PDMS). This research investigates how surface morphology and material structure affect energy generation. By layering PDMS/Al and creating pyramid-shaped patterns, the study found that increasing the number of PDMS/Al layers significantly boosts the output voltage, reaching over 234 mV with three layers. Additionally, increasing the number of pyramid structures from 1 to 36 on PDMS surfaces, while maintaining the same contact area, led to a notable rise in generated voltage due to charge concentration at the pyramid tips. Higher pyramid angles also amplified this effect. These results highlight the importance of structural optimization in maximizing the energy output of TENGs, offering a promising route for more efficient energy harvesting.
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Synthesis of Monodisperse Iron Oxide Nanoparticles with Control of Surface Properties and Magnetization
Dongyeong Gim, Hyeokju Kwon, Minjeong Ha
J Electr Electron Mater 2025;38(1):89-94.   Published online January 1, 2025
DOI: https://doi.org/10.4313/JKEM.2025.38.1.12
Iron oxide nanoparticles (NPs) have gained significant attention for their broad applicability in biomedical imaging, soft robotics, and catalysis owing to their exceptional magnetic properties and biocompatibility. A key challenge in maximizing their functionality lies in achieving a uniform size distribution and dispersity, alongside strong interfacial affinity with the surrounding medium that are essential for optimizing magnetic behavior and processibility. In this study, we present a facile solvothermal synthesis of monodisperse iron oxide NPs with tunable size and controllable surface hydrophobicity by varying precursors, capping agents, and solvents. By varying these synthesis parameters, we demonstrate a clear correlation between NP size, dispersity, and key magnetic properties, including saturation magnetization (MS) and coercivity (HC). This advancement in synthesis methodology offers a reliable, efficient approach for producing high-quality iron oxide NPs, which makes possible for practical use of them across a range of technological and biomedical applications.
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Improvement of Electrical Properties in 4H-SiC MOSFETs by Nitric Oxide Post-Oxidation Annealing
Chang-jun Park, Young-hun Cho, Ji-hyun Kim, Geon-hee Lee, Ye-jin Kim, Seung-hyun Park, Sang-mo Koo
J Electr Electron Mater 2025;38(1):78-83.   Published online January 1, 2025
DOI: https://doi.org/10.4313/JKEM.2025.38.1.10
4H-Silicon carbide (4H-SiC) is a promising material for power and harsh environment devices owing to its superior material properties, including wide bandgap, high critical electric field, and high thermal conductivity. However, despite the advantages of 4H-SiC, its channel mobility is reduced due to the high interface defect density between SiC and the oxide film, leading to increased device switching loss. Therefore, it is necessary to develop new fabrication methods to improve the quality of the SiO2/4H-SiC interface. According to recent research, the effect of high-temperature (1,250~1,300℃) nitric oxide (NO) annealing on the interface states of SiO2/4H-SiC and the channel mobility of 4H-SiC metal-oxide-semiconductor-field-effect transistors (MOSFETs) were investigated. Previous studies have optimized the NO post-oxidation annealing (POA) process, using N2 diluted NO at 1,300℃ to reduce the high SiO2/4H-SiC interface trap density (Dit). This paper focuses on high-temperature (1,250℃) 10% NO annealing to reduce interface defects by integrating nitrogen atoms into the oxide layer near the SiC interface, potentially increasing the channel mobility. Electrical properties such as Dit, threshold voltage (Vth), field-effect mobility (μFE), and specific on-resistance (Ron,sp) were assessed through capacitance-voltage (C-V) and current-voltage (I-V) measurements. It has been confirmed that the interface defect density of the gate oxide film was effectively improved under the POA conditions of 10% NO for 1 hour at 1,250℃.
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