Search Results (352)

Linear passive electrical devices/components are usually characterized in the frequency domain by their impedance, i.e., the ratio of the voltage and current phasors. The use of the impedance concept does not raise particular concerns in low-frequency regimes; however, things become more complicated when it comes to rapid time-varying phenomena, mainly because the voltage depends not only on the position of the points between which it is defined but also on the choice of the integration path that connects them. In this article, based on first principles (Maxwell equations and Poynting vector flow considerations), we discuss the concept of impedance and define it unequivocally for a class of electrical devices/components with rotational symmetry. Two application examples are presented and discussed. One simple example concerns the per-unit-length impedance of a homogeneous cylindrical wire subject to the skin effect. The other, which is more elaborate, concerns a heterogeneous structure that consists of a dielectric disk sandwiched between two metal plates. For the lossless situation, the high-frequency impedance of this device (circular parallel plate capacitor) reaches zero when the frequency reaches a certain critical frequency f_c; then, it becomes inductive and increases enormously when the frequency reaches another critical frequency at 1.6 f_c. The influence of losses on the impedance of the device is thoroughly investigated and evaluated. Impedance corrections due to dielectric losses are analyzed using a frequency-dependent Debye permittivity model. The impedance corrections due to plate losses are analyzed by considering radial current distributions on the outer and inner surfaces of the plates, the latter exhibiting significant variations near the critical frequencies of the device. Full article

Dielectric capacitors have become a key component for energy storage systems, owing to their exceptional power density and swift charge–discharge performance. In a series of lead-free ferroelectric ceramic materials, BaSn_xTi_1-xO₃ (BTS) received widespread attention due to its unique properties. However, BTS ceramics with high Sn content have high efficiency (η) but low recovery energy storage density (W_rec). We incorporated the Sm element into BTS ceramics and aimed to optimize both efficiency and recoverable energy density at moderate Sn content. With the synergistic effect between Sm and Sn, the optimal composition was found at 5% Sn content with 1% low-level Sm dopants, where the energy storage density reached 0.2310 J/cm³ at 40 kV/cm. Furthermore, the thermal stability of the ceramic was investigated using temperature-dependent dielectric spectroscopy, in situ XRD, and temperature-dependent hysteresis loops. With Sm doping, the fluctuation of W_rec decreased from 18.48% to 12.01%. In general, this work not only enhances the understanding of samarium dopants but also proposes strategies for developing lead-free ferroelectric ceramics with superior energy storage properties. Full article

Lead-free ceramic materials have been widely studied since dielectric capacitors became a key component for energy storage. In this work, we adopted defect dipole engineering and improved the energy storage performance of barium zirconate titanate (BZT) ceramics by doping them with MnO₂. With the increase in Mn content, the hysteresis loop changed from a conventional loop to a pinned hysteresis loop, resulting in a decrease in remnant polarization (P_r). When x = 0.02, the recoverable energy storage density (W_rec) reached 0.1561 J/cm² @ 40 kV/cm, a 59% increase from undoped BZT. Further, XPS and EPR analyses confirmed that many oxygen vacancies were generated. We also performed SEM and TEM characterization and observed the microstructures. These results are consistent with theories suggesting that the formation of the pinned hysteresis loop is attributable to oxygen vacancies and defect dipoles. Full article

BaTiO₃-based lead-free ferroelectric films with a large recoverable energy density (W_rec) and a high energy efficiency (η) are crucial components for next-generation dielectric capacitors, which are used in energy conditioning and storage applications in integrated circuits. In this study, grain-engineered (Ba_0.95,Sr_0.05)(Zr_0.2,Ti_0.8)O₃ (BSZT) ferroelectric thick films (~500 nm) were prepared on Si substrates. These films were deposited at 350 °C, 100 °C lower than the temperature at which the LaNiO₃ buffer layer was deposited on Pt/Ti. This method reduced the (001) grain population due to a weakened interface growth mode, while promoting volume growth modes that produced (110) and (111) grains with a high polarizability. As a result, these films exhibited a maximum polarization of ~88.0 μC/cm², a large W_rec of ~203.7 J/cm³, and a high energy efficiency η of 81.2% (@ 6.4 MV/cm). The small-field dielectric constant nearly tripled as compared with that of the same BSZT/LaNiO₃ heterostructure deposited at the same temperature (350 °C or 450 °C). The enhanced linear dielectric response, delayed ferroelectric polarization saturation, and increased dielectric strength due to the nano-grain size, collectively contributed to the improved energy storage performance. This work provides a novel approach for fabricating high-performance dielectric capacitors for energy storage applications. Full article

Since 2015, research on liquid–solid triboelectric nanogenerators (L-S TENGs) has shown steady growth, with the primary focus on application domains such as engineering, physics, materials science, and chemistry. These applications have underscored the significant attention L-S TENGs have garnered in areas like human–nature interaction, energy harvesting, data sensing, and enhancing living conditions. Presently, doping composite dielectric materials and surface modification techniques are the predominant methods for improving the power generation capacity of TENGs, particularly L-S TENGs. However, studies exploring the combined effects of these two approaches to enhance the power generation capacity of TENGs remain relatively scarce. Following a review of existing literature on the use of composite material doping and surface modification to improve the power generation performance of L-S TENGs, this paper proposes an experimental framework termed “self-assembled surface TENG@carbonyl iron particle doping (SAS-TENG@CIP)” to investigate the integrated power generation effects of L-S TENGs when combining these two methods. Research cases and data results indicate that, for TENGs exhibiting capacitor-like properties, the enhancement of power generation performance through composite material doping and superhydrophobic surface modification is not limitless. Each process possesses its own inherent threshold. When these thresholds are surpassed, the percolation of current induced by material doping and electrostatic breakdown (EB) triggered by surface modification can lead to a notable decline in the power output capacity of L-S TENGs. Consequently, in practical applications moving forward, fully realizing the synergistic potential of these methods necessitates a profound understanding of the underlying scientific mechanisms. The conclusions and insights presented in this paper may facilitate their complex integration and contribute to enhancing power generation efficiency in future research. Full article

With the evolution of micro/nanotechnology, anodic aluminum oxide (AAO) has received attention for sensor applications due to its regular and high-aspect-ratio nanopore structure with an excellent sensing performance, especially for electrical and optical sensors. Here, we propose the application of these capacitance and porous properties in a facile nanoporous AAO liquid sensor and study an efficient and economical method for preparing AAO substrates for liquid-phase substance sensing. By applying hybrid pulse anodization (HPA), a growth rate of approximately 5.9 μm/h was achieved in AAO fabrication. Compared to traditional low-temperature (0–10 °C) and two-step anodization with a growth rate of 1–3 μm/h, this process is significantly improved. The effect of pore widening on the performance of electrical sensors is also investigated and discussed. After pore widening, the capacitance values of AAO for air as a reference and various liquids, namely deionized water, alcohol, and acetone, are measured as 3.8 nF, 295.3 nF, 243.5 nF, and 210.1 nF, respectively. These results align with the trend in the dielectric constants and demonstrate the ability to clearly distinguish between different substances. The mechanism of AAO capacitive liquid-phase sensors can mainly be explained from two perspectives. First, since an AAO capacitive sensor is a parallel capacitor structure, the dielectric constant of the substance directly influences the capacitance value. In addition, pore widening increases the proportion of liquid filling the structure, enabling the sensor to clearly differentiate between substances. The other is the affinity between the substance and the AAO sensor, which can be determined using a contact angle test. The contact angles are measured as values of 93.2° and 67.7° before and after pore widening, respectively. The better the substance can fully fill the pores, the higher the capacitance value it yields. Full article

In this research work, two distinct types of three-dimensional (3D) capacitors were successfully fabricated, each with its own unique features and advantages. The first type of capacitor is centered around a 3D nanoporous structure. This structure is formed on a nickel substrate through anodic oxidation. After undergoing high-temperature thermal oxidation, a monolithic Ni-NiO-Pt metal–insulator–metal (MIM) capacitor with a nanoporous dielectric architecture is achieved. Structurally, this innovative design brings about several remarkable benefits. Due to the nanoporous structure, it has a significantly increased surface area, which can effectively store more charges. As a result, it exhibits an equivalent capacitance density of 69.95 nF/cm², which is approximately 18 times higher than that of its planar, non-porous counterpart. This high capacitance density enables it to store more electrical energy in a given volume, making it highly suitable for applications where miniaturization and high energy storage in a small space is crucial. The second type of capacitor makes use of Through-Glass Via (TGV) technology. This technology is employed to create an interdigitated blind-via array within a glass substrate, attaining an impressively high aspect ratio of 22.5:1 (with a via diameter of 20 μm and a depth of 450 μm). By integrating atomic layer deposition (ALD), a conformal interdigital electrode structure is realized. Glass, as a key material in this capacitor, has outstanding insulating properties. This characteristic endows the capacitor with a high breakdown field strength exceeding 8.2 MV/cm, corresponding to a withstand voltage of 5000 V. High breakdown field strength and withstand voltage mean that the capacitor can handle high-voltage applications without breaking down easily, which is essential for power-intensive systems like high-voltage power supplies and some high-power pulse-generating equipment. Moreover, due to the low-loss property of glass, the capacitor can achieve an energy conversion efficiency of up to 95%. Such a high energy conversion efficiency ensures that less energy is wasted during the charge–discharge process, which is highly beneficial for energy-saving applications and systems that require high-efficiency energy utilization. Full article

The gate reliability issues in SiC-based devices with a gate dielectric formed through heat oxidation are important factors limiting their application in power devices. Aluminum oxide (Al₂O₃) and titanium dioxide (TiO₂) were combined using the ALD process to form a composite AlTiO gate dielectric on a 4H-SiC substrate. TDMAT and TMA were the precursors selected and deposited at 200 °C, and the samples were Ar or N₂ annealed at temperatures ranging from 300 °C to 700 °C. An XPS analysis suggested that the AlTiO film had been deposited with a high overall quality and the involvement of Ti atoms had increased the interfacial bonding with the substrate. The as-deposited MOS structure had band shifts of ΔE_C = 1.08 eV and ΔE_V = 2.41 eV. After annealing, the AlTiO bandgap increased by 0.85 eV at most, and better band alignment was attained. Leakage current and breakdown voltage characteristic investigations were conducted after Al electrode deposition. The leakage current density and electrical breakdown field of an MOS capacitor structure with a SiC substrate were ~10⁻³ A/cm² and 6.3 MV/cm, respectively. After the annealing process, both the measures of the JV performance of the MOS capacitor had improved to ~10⁻⁶ A/cm² and 7.2 MV/cm. The interface charge N_eff of the AlTiO layer was 4.019 × 10¹⁰ cm⁻². The AlTiO/SiC structure fabricated in this work proved the feasibility of adjusting the properties of single-component gate dielectric materials using the ALD method, and using a suitable thermal annealing process has great potential to improve the performance of the compound MOS dielectric layer. Full article

In this study, we analyzed the electrical characteristics of metal–insulator–metal (MIM) capacitors fabricated with reference to insulator (Si_xN_y) thickness and deposition condition. Si_xN_y thicknesses of 650 Å, 500 Å, and 400 Å were used with four different conditions designated as MIM (N content 1.49), NEWMIM (N content 28.1), DAMANIT (N content 1.43), and NIT (N content 0.30), deposited by controlling gas flow and RF power as a function of N content. Capacitor characteristics were evaluated mainly in terms of the relationship between leakage current and breakdown voltage (BV). Current–voltage (I–V) characterizations revealed that a higher N–H/Si–H ratio effectively suppressed trap-assisted leakage conduction and enhanced dielectric robustness under high-field stress. Among the tested conditions, the NEWMIM process demonstrated the most favorable electrical performance with highest N contents. The MIM and NEWMIM conditions proved most effective among the evaluated processes, achieving sufficient BV values (>20 V) for reliable MIM capacitor operation and proposing a process optimization framework for integrating medium-density Si_xN_y–based MIM capacitors (2 fF/µm²) with sufficiently high BV values in the future. Full article

Accurate parameter estimation is essential for effective monitoring and treatment of high-salinity industrial wastewater. Traditional methods such as spectroscopy, ion chromatography, and electrochemical analysis offer high sensitivity but are often complex, costly, and unsuitable for real-time monitoring. This research integrates Deep Neural Networks (DNNs) with the Levenberg–Marquardt (LM) algorithm to develop an advanced RFID-based sensing system for real-time monitoring of sodium chloride solutions in wastewater. The DNN extracts essential features from raw data, while the LM algorithm optimizes parameter estimation for enhanced precision and stability. Experimental results show that the dielectric constant sample variance at various flow rates under wireless frequency is 0.08509, while the sample total variance is 0.06807, both below 0.1. Additionally, the sample standard deviation and total standard deviation are both below 0.3, at 0.26090 and 0.29169, respectively. These findings confirm that the proposed system is robust against flow rate variations, ensuring accurate, real-time monitoring and supporting sustainable industrial practices. Full article

Dynamic random-access memory (DRAM) is a vital component in modern computing systems. Enhancing memory performance requires maximizing capacitor capacitance within DRAM cells, which is achieved using high-k dielectric materials deposited as thin, uniform films via atomic layer deposition (ALD). Precise film deposition that minimizes electronic defects caused by charged vacancies is essential for reducing leakage current and ensuring high dielectric strength. In this study, we fabricated metal–insulator–metal (MIM) capacitors in high-aspect-ratio trench structures using remote plasma ALD (RP-ALD) and direct plasma ALD (DP-ALD). The trenches, etched into silicon, featured a 7:1 aspect ratio, 76 nm pitch, and 38 nm critical dimension. We evaluated the electrical characteristics of HfO₂-based capacitors with TiN top and bottom electrodes, focusing on leakage current density and equivalent oxide thickness. Capacitance–voltage analysis and X-ray photoelectron spectroscopy (XPS) revealed that RP-ALD effectively suppressed plasma-induced damage, reducing defect density and leakage current. While DP-ALD offered excellent film properties, it suffered from degraded lateral uniformity due to direct plasma exposure. Given its superior lateral uniformity, lower leakage, and defect suppression, RP-ALD shows strong potential for improving DRAM capacitor performance and serves as a promising alternative to the currently adopted thermal ALD process. Full article

This study presents the fabrication and characterization of magnetically active textiles using cotton fibers impregnated with suspensions of pumpkin seed oil, carbonyl iron microparticles, and propolis microparticles. The textiles were utilized to manufacture planar capacitors, enabling an investigation of the effects of static magnetic fields and the introduced microparticles on the components of complex dielectric permittivity. The results reveal that the dielectric properties of the fabricated textiles are highly sensitive to the applied magnetic field intensity, the frequency of the alternating electric field, and the composition of the impregnating suspension. The experimental findings suggest that the dielectric loss and permittivity can be finely tuned by adjusting the magnetic flux density and the proportion of propolis microparticles. The multifunctional nature of these magnetically responsive textiles, combined with the bioactive properties of the incorporated natural components, opens promising pathways for applications in smart textiles, biomedical devices, and sensor technologies. Full article

High-temperature performance is crucial for dielectric capacitors, especially in military and aerospace applications, as they offer superior charge–discharge rates and power density compared to supercapacitors and batteries. However, the stability of polymers based on commercial dielectric capacitors under extreme environmental conditions (i.e., ≥100 °C) presents significant challenges. Herein, with polyimide (PI) as the matrix, a middle layer is produced that is rich in zero-dimensional nanoparticles, BaTiO₃ (0DBTO@PI), to enhance dielectric polarization. The upper and lower layers integrate two-dimensional laminated Al₂O₃ (2DAO@PI) as thermal conductive and insulating layers to improve heat dissipation and electrical insulation. The composites combine polarization enhancement and thermal management to synergistically improve high-temperature capacitive energy storage. As a result, the designed composite capacitors maintain good performance at temperatures > 150 °C. Even at 200 °C, it retains 2.36 J cm⁻³ (a 203% increase over pure PI), demonstrating unprecedented stability under extreme temperatures. Layer-specific functionalization provides a new and significant paradigm for designing high-temperature polymer-based energy storage films. Full article

This study presents the fabrication and characterization of hybrid magneto-responsive composites (hMRCs), composed of recyclable components: magnetite microparticles (MMPs) as fillers, lard as a natural binding matrix, and cotton fabric for structural reinforcement. MMPs are obtained by in-house plasma-synthesis, a sustainable, efficient, and highly tunable method for producing high-performance MMPs. hMRCs are integrated into flat capacitors, and their electrical capacitance (C), resistance (R), dielectric permittivity (${ϵ}^{\prime }$), and electrical conductivity ($\sigma$) are investigated under a static magnetic field, uniform force field, and an alternating electric field. The experimental results reveal that the electrical properties of hMRCs are dependent on the volume fractions of MMPs and microfibers in the fabric, as well as the applied magnetic flux density (B) and compression forces (F). C shows an increase with both B and F, while R decreases due to improved conductive pathways formed by alignment of MMPs. $\sigma$ is found to be highly tunable, with increases of up to 300% under combined field effects. In the same conditions, C increases up to 75%, and R decreases up to 80%. Thus, by employing plasma-synthesized MMPs, and commercially available recyclable lard and cotton fabrics, this study demonstrates an eco-friendly, low-cost approach to designing multifunctional smart materials. The tunable electrical properties of hMRCs open new possibilities for adaptive sensors, energy storage devices, and magnetoelectric transducers. Full article

Solution-processed metal oxide dielectrics often result in unstable thin-film transistor (TFT) performance, hindering the development of next-generation metal oxide electronics. In this study, we prepared fluorine (F)-doped zirconium oxide (ZrO₂) dielectric layers using a chemical solution method to construct TFTs. The characterization by X-ray photoelectron spectroscopy (XPS) revealed that appropriate fluoride doping significantly reduces oxygen vacancies and the concentration of hydroxyl groups, thereby suppressing polarization processes. Subsequently, the electrical properties of Al/F:ZrO₂/n⁺⁺Si capacitors were evaluated, demonstrating that the optimized 10% F:ZrO₂ dielectric exhibits a low leakage current density and stable capacitance across a wide frequency range. Indium zinc oxide (IZO) TFTs incorporating 10% F:ZrO₂ dielectric layers were then fabricated. These devices displayed reliable electrical characteristics, including high mobility over a broad frequency range, reduced dual-sweep hysteresis, and excellent stability under positive-bias stress (PBS) after three months of aging. These findings indicate that the use of the fluorine-doped ZrO₂ dielectric is a versatile strategy for achieving high-performance metal oxide thin-film electronics. Full article