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Basic multimode impedance analysis, based on the availability of nonequilibrium charge carriers and their delayed return to equilibrium, is employed to assess the state of equivalent circuit representations. This analysis highlights the necessity of surpassing these representations in nonlinear systems with inherent memory, along with their associated advantages and limitations. On the basic grounds of generation and recombination (or trapping) of nonequilibrium carriers and their relaxation times, we show how seeming complexity of frequency-dependent impedance that matches a vast universe of experimental evidences can be reduced to simple combinations of basic microscopic ingredients. Counterintuitive features, such as negative capacitances or unexpected inductances, arise when the results are projected onto linear equivalent circuit representations. This indicates the presence of certain limitations and potential ambiguities in the symbolic representation of "equivalent" circuits. Our approach further provides a microscopic perspective that exposes the linkage of an apparent flux with an apparent inductance dismissing any magnetic essence. [ABSTRACT FROM AUTHOR]

A deep learning neural network-assisted design strategy for programmable piezoelectric phononic crystal (PnC) beams with shunt circuits is proposed. The feasibility of integrating deep learning into the design of tunable PnCs to achieve real-time vibration isolation is demonstrated through numerical examples. The influence of shunt circuits (capacitance) on bandgaps of piezoelectric PnCs is studied by finite element (FE) simulations. The results show that the bandgap frequency and range vary with the capacitance and electrode length. Moreover, incorporating supercell structures introduces an additional bandgap, significantly expanding the tunable range of the bandgap and demonstrating that shunt circuit modifications can tailor the frequency and width of the bandgap. A suite of deep learning neural network (NN) algorithms is developed for predicting bandgaps and inversely designing PnC parameters, greatly accelerating the bandgap calculation and enabling faster inverse design than existing models. The accuracy of the NN algorithms is verified by comparing their predictions with those from FE simulations. The combination of designed PnC beams and deep learning NNs enables real-time vibration reduction and isolation. This design strategy is successfully validated in a practical scenario involving real-time vibration isolation of train rails. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) reduced graphene oxide (rGO)/Ti2CTx MXene hybrid aerogels were effectively prepared by a two-step method involving hydrothermal reaction and freeze-drying. The intimately coupled rGO/Ti2CTx hybrid aerogel combined high electrical conductivity, large interlayer spacing, and excellent mechanical stability of Ti2CTx, which not only effectively prevents the self-restacking of Ti2CTx nanosheets, exposes more active sites exposed, and improves the volume change during the charge/discharge process but also increases the accessibility of ions and promotes the rapid transfer of ions/electrons. As a result, rGO/Ti2CTx 17.5–2.5 as the working electrode of electric double layer capacitors delivers a large specific capacity (107.05 F g−1 at 0.5 A g−1 in a 1M Na2SO4 electrolyte), a high rate capability (maintains 30% of its initial capacitance at 10 A g−1, which is much better than rGO and Ti2CTx), and excellent long-term large-current cycle stability (the initial capacitance remains above 71.1% after 10 000 cycles at 1 A g−1). In addition to providing a high-performance electrode for supercapacitors, this study proposes an efficient and time-saving strategy for constructing 3D structures from 2D materials. [ABSTRACT FROM AUTHOR]

Self-sustained electrical oscillations (SEOs) in VO2 films have attracted considerable attention owing to their potential to emulate spiking pulses in neuromorphic circuits. However, triggering stable SEOs and the controlling oscillation frequency remain challenging because the details of circuit operation with VO2-based devices are not yet well understood. In this study, we propose a method to observe SEOs stably in a VO2-based planar device with Au/Ti facing electrodes by introducing a 50 Hz sinusoidal voltage from a curve tracer. The transient aspects, including the onset and collapse of the SEO, were captured, providing clarity on the oscillation frequency range and circuit conditions for the SEOs, which are closely correlated with the device temperature. It became clear that the parallel capacitance not only determined the oscillation frequency but also controlled the current through VO2 just after the insulator–metal transition of VO2, playing a role in triggering stable oscillations. We also successfully observed the transient aspects from in-phase to anti-phase synchronized oscillations in the coupled oscillations. This study advances the experimental procedures and applications of SEOs in VO2-based planar devices. [ABSTRACT FROM AUTHOR]

A ledge feature in the capacitance–voltage (CV) profiles of Ga2O3 MOS (metal–oxide–semiconductor) capacitors is investigated using UV-assisted CV measurements. A model is presented whereby the capacitance ledge is associated with carrier trapping in deep-level states at the Al2O3/Ga2O3 interface. Following UV assisted emptying of interface traps at a constant bias, a voltage ramp toward flatband results in a CV ledge when the trap recombination current becomes equal to the quasi-static sweep charging current. The ledge continues until all the traps below the corresponding pinned surface potential have been filled. Varying the UV energy varies the ledge voltage range and allows a density of states to be determined as a function of energy. A broad interface state peak with maximum density ∼8 × 1012 cm−2 eV−1 for deep trap energies lying between 2.4 and 4.1 eV below the conduction band (CB) edge is extracted. Using the conductance method, the interface trap density is also found to rise toward the CB edge in the range 0.25–0.45 eV below the CB edge, reaching a maximum density of ∼1 × 1012 cm−2 eV−1. Combining these two techniques, an interface trap distribution is estimated for almost the entirety of the bandgap of Ga2O3. This novel technique probes deep interface states where standard methods fail to quantify interface states reliably. [ABSTRACT FROM AUTHOR]

In this work, we propose and validate a generalization of the Helmholtz model that can account for both "bell-shaped" and "camel-shaped" differential capacitance profiles of concentrated electrolytes, the latter being characteristic of ionic liquids. The generalization is based on introducing voltage dependence of both the dielectric constant "ϵr(V)" and thickness "L(V)" of the inner Helmholtz layer, as validated by molecular dynamics (MD) simulations. We utilize MD simulations to study the capacitance profiles of three different electrochemical interfaces: (1) graphite/[BMIm+][ BF 4 − ] ionic liquid interface; (2) Au(100)/[BMIm+][ BF 4 − ] ionic liquid interface; (3) Au(100)/1M [Na+][Cl−] aqueous interface. We compute the voltage dependence of ϵr(V) and L(V) and demonstrate that the generalized Helmholtz model qualitatively describes both camel-shaped and bell-shaped differential capacitance profiles of ionic liquids and concentrated aqueous electrolytes (in lieu of specific ion adsorption). In particular, the camel-shaped capacitance profile that is characteristic of ionic liquid electrolytes arises simply from combination of the voltage-dependent trends of ϵr(V) and L(V). Furthermore, explicit analysis of the inner layer charge density for both concentrated aqueous and ionic liquid double layers reveal similarities, with these charge distributions typically exhibiting a dipolar region closest to the electrode followed by a monopolar peak at larger distances. It is appealing that a generalized Helmholtz model can provide a unified description of the inner layer structure and capacitance profile for seemingly disparate aqueous and ionic liquid electrolytes. [ABSTRACT FROM AUTHOR]

This study illustrates the successful achievement of tunable defect bands in one-dimensional defective phononic crystals (PnCs) through the incorporation of piezoelectric defects with synthetic negative capacitances (SNCs) for the first time. The efficacy of SNCs in creating tunable bandpass filters across a broad frequency range is thoroughly examined using the proposed analytical and numerical models. A newly developed electroelastically coupled transfer matrix that incorporates SNCs is presented, considering either series or parallel connection between bimorph piezoelectric elements. Defect band and transmittance analyses are conducted using the transfer matrix and S-parameter methods. Two key findings emerge from this investigation. First, when the total equivalent capacitance of the bimorph piezoelectric elements and SNC becomes zero, the defect band representing the point-symmetric defect-mode shape can be customized throughout the entire phononic bandgap. Second, the constant transmittance value, resembling short-circuit conditions, highlights the remarkable ability of SNCs to tune defect bands without energy dissipation, paving the way for fully tunable bandpass filters. To propel this research forward, future investigations could explore expanding the design space with double defects, adopting enhanced modeling techniques to account for lateral and shear effects, developing a control algorithm for the automatic optimization of SNC values in actively tunable bandpass filters, and incorporating artificial intelligence into design methods for piezoelectric defects with electrical connections. [ABSTRACT FROM AUTHOR]

The deviations of cryogenic collector current–voltage characteristics of SiGe heterojunction bipolar transistors (HBTs) from ideal drift-diffusion theory have been a topic of investigation for many years. Recent work indicates that direct tunneling across the base contributes to the non-ideal current in highly scaled devices. However, cryogenic discrepancies have been observed even in older-generation devices for which direct tunneling is negligible, suggesting that another mechanism may also contribute. Although similar non-ideal current–voltage characteristics have been observed in Schottky junctions and were attributed to a spatially inhomogeneous junction potential, this explanation has not been considered for SiGe HBTs. Here, we experimentally investigate this hypothesis by characterizing the collector current ideality factor and built-in potential of a SiGe HBT vs temperature using a cryogenic probe station. The temperature dependence of the ideality factor and the relation between the built-in potential as measured by capacitance–voltage and current–voltage characteristics are in good qualitative agreement with the predictions of a theory of electrical transport across a spatially inhomogeneous junction. These observations suggest that inhomogeneities in the base–emitter junction potential may contribute to the cryogenic non-idealities. This work helps to identify the physical mechanisms limiting the cryogenic microwave noise performance of SiGe HBTs. [ABSTRACT FROM AUTHOR]

We have developed and implemented an implicit electrolyte model in the Vienna Ab initio Simulation Package (VASP) that includes nonlinear dielectric and ionic responses as well as a nonlocal definition of the cavities defining the spatial regions where these responses can occur. The implementation into the existing VASPsol code is numerically efficient and exhibits robust convergence, requiring computational effort only slightly higher than the original linear polarizable continuum model. The nonlinear + nonlocal model is able to reproduce the characteristic "double hump" shape observed experimentally for the differential capacitance of an electrified metal interface while preventing "leakage" of the electrolyte into regions of space too small to contain a single water molecule or solvated ion. The model also gives a reasonable prediction of molecular solvation free energies as well as the self-ionization free energy of water and the absolute electron chemical potential of the standard hydrogen electrode. All of this, combined with the additional ability to run constant potential density functional theory calculations, should enable the routine computation of activation barriers for electrocatalytic processes. [ABSTRACT FROM AUTHOR]

Electrode–electrolyte interfacial properties characterize the functioning of electrochemical devices, and reactive molecular dynamics simulations, using reactive force fields (ReaxFF) and charge equilibration (QEq) techniques, are classical atomistic methods for investigating the processes that govern the device properties. However, the numerical implementation of ReaxFF and QEq treats Coulomb interaction with a short-distance cutoff for computational speed, thereby limiting interactions among atoms to a domain containing only their neighbor lists. Excluding long-distance Coulomb interactions makes the description of electrostatics in large-scale systems intractable. We apply Ewald sum in the extension of ReaxFF to include long-range Coulomb (LRC) interactions and investigate the effect of the inclusion on the electrostatic and capacitive properties of graphene–water interfaces at different applied potentials in comparison with the original ReaxFF. The study shows that with the inclusion of long-range Coulomb, the capacitance amounts to 4.9 ± 0.2 μF cm−2 compared with 4.4 ± 0.2 μF cm−2 predicted by the original ReaxFF [with short-range Coulomb (SRC)]; thus, indicating that SRC underestimates the capacitance of water between graphene walls by 12% when compared with the 5.0 μF cm−2 predicted with the extended simple point charge (SPC/E) water model. Thus, the results indicate that LRC ReaxFF/QEq have the ability and advantage to model electrochemical processes at a more realistic Coulomb interaction description and foster the processing of the details about the operation of electrochemical devices than the SRC. [ABSTRACT FROM AUTHOR]

In this article, a compact and high-gain, wide steering range and very low cross-polarization level holographic metasurface for beam steering is presented. The triangular modulated impedance surface is used for radiating the desired wave. The direction of the radiated beam is controlled through the varactor diode by changing the surface impedance of the device. The two prototypes of the designed device have been fabricated with two different varactor diodes. A higher gain of 11.7 dBi with a lower beam steering range of 25° and a radiation efficiency above 70% has been obtained from the device with a varactor diode SMV1405-079LF having lower parasitic resistance and larger capacitance properties. However, another fabricated device with higher parasitic resistance and lower capacitance property varactor diode SMV2201-40LF gives a lower gain of 9.1 dBi, a radiation efficiency below 55%, and a larger beam steering range of 61°. The experimental results are in good agreement with the simulation ones. The proposed device can be used for various applications like autonomous vehicles, toll plazas, and satellite communication. [ABSTRACT FROM AUTHOR]

In this paper, a high‐gain bidirectional DC–DC converter is presented for electric vehicles where low terminal voltage source like a supercapacitor is used along with the battery. The supercapacitor provides or absorbs large amount power during acceleration and deacceleration and extends the life of main energy source, that is, battery. The supercapacitor terminal voltage varies considerably during charging and discharging activities; hence, a bidirectional DC–DC converter with a high‐voltage conversion ratio must be used to connect the lower supercapacitor voltage to the higher DC‐link voltage. Such application requires steep voltage conversion ratio along with continuous gain‐based bidirectional DC–DC converters. In this study, a typical CuK converter is employed to produce a voltage gain of 3X and X/3 with the ability to transmit power in both directions. The suggested bidirectional converter has a continuous current on both the low‐ and high‐voltage sides, which reduces the requirement for filter capacitance and increases the lifespan of the supercapacitor and DC‐link capacitor. Further, inherent inrush current safety is provided by the proposed converter as the inclusion of an inductor in the path of capacitor charging or discharging. Both in the charging and discharging phases, a detailed steady‐state analysis of the proposed circuit was performed. Moreover, a deep discharge analysis of the supercapacitor and its implication on the performance of the converter is also investigated. [ABSTRACT FROM AUTHOR]

Summary: In this paper, a systematic research of the effects of second source harmonics caused by gate‐source capacitance in the design of a series of continuous mode (SCM) power amplifiers (PAs) is first presented. The research results show that, compared to the conventional SCMs that require the input second harmonic to be short circuited, SCMs under the impact of input nonlinearity have a more flexible input second harmonic manipulation space, and to further improve and maintain the performance of PAs in wideband operations, a new impedance design space is explored through analysis. For practical validation, SCMs PA considering the effects of the input nonlinearity is designed and fabricated with a 10‐W gallium nitride (GaN) device, acquiring 39.1–42 dBm output power and 60.6–71.5% drain efficiency (DE) performance at a 3 dB gain compression level operating over the 0.5–3.5 GHz frequency range with a relative bandwidth of 150%. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes a method for capacitance health monitoring (CHM) of submodule capacitors in modular multilevel converters (MMCs) that uses a reduced number of voltage sensors. In the proposed method, the MMC arms are divided into some groups of submodules and one voltage sensor is used for each group. In addition, a capacitor voltage estimation technique with minimal computational complexity is used to determine the capacitor voltage. The ratio of the estimated to measured capacitor voltage during positive arm current is also used to demonstrate a simple and efficient capacitance monitoring method. Moreover, contrary to the limitations associated with traditional CHM methods, the proposed method reduces the required voltage sensors and minimizes data exchange between the power system and the central processor. The effectiveness of the proposed method is validated through simulation and experimental results under various operating conditions. [ABSTRACT FROM AUTHOR]

The delay of a diffusion-controlled faradaic reaction was revisited by ac-impedance in the light of the ambiguous concept of the conventionally heterogeneous kinetics because of not only scattered values of rate constant but also participation in the negatively capacitive current at ac high frequency. It was examined by use of the redox reaction for a ferrocenyl derivative in KCl aqueous solution at a platinum thin wire electrode. The Nyquist plots at various dc-potentials showed lines, as in the well-known behavior. The double layer (DL)-corrected real admittance was sufficiently controlled by diffusion, whereas values of the corrected imaginary admittance got smaller than those of the real one with an increase in ac-frequency, taking even negative values. The difference between the two admittances can be regarded as the negatively capacitive current or the delay of ac-response, which is associated with the faradaic reaction. It is caused by the gradual stabilization of the orientation of dipoles generated by the electrode reaction, which depresses the capacitance over the DL capacitance. The delay is akin to the frequency dispersion of the DL and is regarded as a quasi-solid state structure. The expressions for the delayed ac-current were derived, which included both the negative capacitance and the phase angle. The delay was compared with the Butler-Volmer kinetics. [ABSTRACT FROM AUTHOR]

Present work reports on the synthesis of NiO-incorporated nanotorous ZrO2 synthesized by facile co-precipitation method for supercapacitor application. The as-synthesized composite was characterised using FTIR and XRD confirming the successful synthesis of ZrO2-NiO composite (ZNC). FESEM analysis also revealed morphology transition from nanoclusters of tiny ZrO2 particles and stacked flakes of NiO to self-assembled nanotorus ZNC. Electrochemical analyses (like CV, GCD, EIS) also revealed improved electrochemical behaviour of ZrO2 whose specific capacitance increased from 87.77 F/g to 251 F/g in ZNC at 1 A/g. This could be attributed to the synergistic effect of nanotorous morphology in the presence of NiO. These observations were well complemented by a reduced band gap (~ 2.96 eV) and lower charge transfer and solution resistance. A mechanistic insight was also proposed for a deeper understanding of the development of torous structured material. This work provides a closer look into how NiO-driven torous morphology of ZrO2-NiO composite has improved the electrochemical performance of ZrO2. [ABSTRACT FROM AUTHOR]

The vibration energy of the track slab can be converted into electric energy for wireless sensors by piezoelectric energy harvesters. A track laminated circular plate harvester (TLCP harvester) is designed in this paper based on foundation excitation. The central frequency of the harvester is 222 Hz, which is matched with the 222.8 Hz of the track slab. The stiffness curve, damping, equivalent capacitance, and electromechanical coupling coefficient of the harvester are obtained through the experiment. The harmonic balance method and Runge–Kutta's voltage results are consistent with the experimental results. The frequency responses verify the jump phenomenon and soft characteristics. The experiment results show that the maximum output power is 8.07 mW under 7 kΩ load resistance, and the maximum RMS power is 0.3804 mW under 5 kΩ load resistance. This paper develops a safe and high-efficiency piezoelectric energy harvester for track slabs. [ABSTRACT FROM AUTHOR]

High-k dielectric insulators are required to reduce leakage and increase transistor performance. They are able to impact the mobility of carriers in transistors positively, leading to better device performance in advanced transistor architecture. Nevertheless, an in-depth analysis of how high-k dielectric insulators influence transistor characteristics must be carried out to determine their suitability. The objective of this study is to investigate the impact of high-k insulators towards electrical properties of junctionless double gate strained transistor. The simulation works is done using process/device simulator Silvaco Athena/Atlas. Based on the retrieved results, the magnitude of ION, on-off ratio, gm, and Cint for TiO2-based device are approximately 63%, 99%, 62%, and 89% respectively higher than the lowest permittivity materialbased device. The TiO2-based device also exhibits the lowest magnitude in IOFF and SS compared to others. However, a significant degradation in fT magnitude have been observed for TiO2-based device significantly due to its large capacitances. [ABSTRACT FROM AUTHOR]

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A flexible capacitive three-dimensional (3D) force transducer with four bottom electrodes is proposed. A dielectric layer with ionic effects and pyramid-like microstructures is designed to improve the sensing performance of this sensor. The arrayed sensor exhibits remarkable capabilities in capturing and decoupling 3D forces, showcasing a high sensitivity, a wide response range (0–30 kPa), rapid response time (62 ms), excellent repeatability under continuous pressure, as well as static and dynamic responses. By assembling a robotic arm to grasp various objects, the sensor demonstrates exceptional sensing capabilities for object roughness, thereby highlighting its potential application as a touch recognition system in human–computer interaction scenarios. [ABSTRACT FROM AUTHOR]

An improved 4H‐SiC SBD‐wall‐integrated trench metal‐oxide‐semiconductor (SWITCH‐MOS) with n‐bury and split‐gate is proposed. Under the premise of ensuring breakdown voltage (BV), the n‐bury layer can smooth the path to current conduction, which reduces the specific on‐resistance (RON, SP) and improves static characteristics. Besides, the split‐gate is able to transform the gate‐drain capacitance (CGD) and improve the dynamic characteristics. Therefore, a superior forward performance that SWITCH‐MOS always craves is achieved. According to the simulation results, compared to the conventional SWITCH‐MOS with almost the same BV, the proposed one reduces the RON, SP by 57% and the CGD by 59% while gaining equally advanced reverse performance. Its reverse conduction voltage is only −1.78 V, but its figure of merit reaches 1.67 GW/cm2 and 65 mΩ·nC, which is attractive for the application in power inverters. [ABSTRACT FROM AUTHOR]

ABSTRACT The transimpedance amplifier (TIA) is an essential component in optical communication systems. It converts the photodiode current to a voltage for further processing. In this paper, a novel CMOS current‐mirror‐based TIA is proposed. Its suitability to optical communication systems is verified. The current‐mirror topology is chosen due to its low input resistance and highly linear current amplification. The proposed TIA employs negative feedback and shunt‐inductive peaking to extend the bandwidth. Three configurations of the shunt‐inductive peaking are explored: one with passive inductors and two with active inductors. The proposed TIA is verified by simulation using the 45‐nm CMOS technology with a 1‐V supply and 1‐pF photodiode capacitance with the key performance trade‐offs discussed. A figure of merit (FoM) is introduced to evaluate the performance of the proposed TIA. The simulation results of the proposed TIA with passive inductors show a gain of 30.6 dB, a 3‐dB bandwidth of 2.8 GHz, and a power consumption of 1.63 mW, with an input‐referred noise current of 23.55 pA/√Hz. [ABSTRACT FROM AUTHOR]

Herein, a Bi2Fe4O9@Bi25FeO40 heterostructure with a high specific surface area of 30.07 m² g-1 and abundant heterogeneous interfaces was successfully fabricated and applied to supercapacitors for the first time. The Bi2Fe4O9@Bi25FeO40 electrode exhibits a high specific capacity (550.8 F g-1 at 1.0 A g-1) and good cycling stability (75% capacitance retention and 92.3% coulombic efficiency after 3000 cycles at 5.0 A g-1), significantly outperforming the pure Bi2Fe4O9 or Bi25FeO40 electrode. This work proposes an effective interfacial engineering strategy to enhance supercapacitor performance. [ABSTRACT FROM AUTHOR]

Supercapacitors, as promising energy storage devices, have gained significant attention due to their ability to deliver high power and efficient charge storage mechanisms. In this work, we report the synthesis and electrochemical characterization of pristine NiO and Ni 1-x Ce x O (x = 0.01, 0.02, 0.03) nanoparticles using a single-step auto ignition combustion method. Preliminary investigations indicate that Ni 1-x Ce x O (x = 0.02) nanoparticles (2 % Ce doping) exhibit superior specific capacitance compared to other compositions. Therefore, we focused on structural, morphological, and vibrational studies on pristine and 2 % Ce-doped NiO. XPS and BET techniques were explored to assess the electronic state and porosity of the samples. Subsequent electrochemical performance evaluations included Cyclic Voltammetry (CV) at various scan rates, Galvanostatic Charge-Discharge (GCD), and Electrochemical Impedance Spectroscopic (EIS) techniques. From CV at a scan rate of 5 mVs−1, specific capacitance values of 419 Fg-1 and 604 Fg-1 were obtained for pristine and 2 % Ce-doped NiO, respectively. GCD studies revealed a specific capacitance of 381 Fg-1 for 2 % Ce-doped NiO at a current density of 1 Ag-1 and demonstrated capacitance retention of 95.1 % over 3000 GCD cycles for a current density of 4 Ag-1. The symmetric two-electrode supercapacitor cell demonstrates exceptional electrochemical performance, exhibiting a high specific capacitance of 122 Fg-1, an impressive energy density of 8.17 WhKg−1, a power density of 700 WKg-1 at 1 Ag-1, and a remarkable 88 % capacitance retention after 5000 GCD cycles. DFT calculations suggest that Ce doping significantly alters pristine NiO's electronic and structural features due to lattice strain. Our work highlights the enhanced electrochemical performance of 2 % Ce-doped NiO and its potential as a good-quality supercapacitor material. [ABSTRACT FROM AUTHOR]

Suspending devices on thin SiN membranes can limit their interaction with the bulk substrate and reduce parasitic capacitance to ground. While suspending devices on membranes are used in many fields including radiation detection using superconducting circuits, there has been less investigation into maximum membrane aspect ratios and achievable suspended device quality, metrics important to establish the applicable scope of the technique. Here, we investigate these metrics by fabricating superconducting coplanar waveguide resonators entirely atop thin (∼ 110 nm) SiN membranes, where the membrane's shortest length to thickness yields an aspect ratio of approximately 7.4 × 10 3 . We compare these membrane resonators to on-substrate resonators on the same chip, finding similar internal quality factors ∼ 10 5 at single photon levels. Furthermore, we confirm that these membranes do not adversely affect resonator thermalization and conduct further materials characterization. By achieving high quality superconducting circuit devices fully suspended on thin SiN membranes, our results help expand the technique's scope to potential uses including incorporating higher aspect ratio membranes for device suspension and creating larger footprint, high impedance, and high quality devices. [ABSTRACT FROM AUTHOR]

Designing potential architectures by the modification of conventional electrode materials is an effective approach in the development of high performance supercapacitor electrodes. The present study investigated the effect of varying anodization voltages (50, 75, and 100 V) on the morphology and electrochemical properties of titanium nanotubes (TNT). Molybdenum was doped onto TNT using a simple hydrothermal procedure, followed by thermal treatment at 450 °C. The study effectively demonstrated control over the dimensions of the nanotube structure by adjusting the anodization voltage. Additionally, it was found that the tube diameters were increased due to etching during the hydrothermal treatment with the Mo precursor, which potentially enhanced the supercapacitive performance of Mo‐doped TNT. Further, structural analysis revealed that Mo doping improved both crystallinity and electrode stability. With an optimal anodization voltage of 100 V, TNT and Molybdenum‐doped TNT could exhibit capacitance value of 13.34 and 326.54 mF cm−2 respectively, at a current density of 1 mA cm−2. Furthermore, the electrode demonstrated good cyclic stability with 88% capacitance retention and 97% coulombic efficiency after 5000 cycles. An impressive energy density of 87.03 µWh cm−2 and a power density of 799.99 µW cm−2 could be achieved with this sample in an asymmetrical device. [ABSTRACT FROM AUTHOR]

Achieving a high storage capability while maintaining good rate performance using symmetric microsupercapacitors (MSCs) remains challenging. Herein, a 3D symmetric MSC based on interdigitated 3D bicontinuous pseudocapacitive electrodes is proposed to simultaneously attain ultrahigh energy density and ultrafast response. The 3D electrodes comprise electrolytically active MnO2 layers conformally coated onto a 3D periodic porous Ni current collector. In this architecture, the low conductivity of MnO2 can be compensated by efficient charge transport and facile charge transfer without compromising its high capacitance. The 3D MSC with a 1‐V window exhibits an ultrahigh volumetric energy density of 15.8 mWh cm−3 with a high power density of 4.95 W cm−3, outperforming all previously reported MnO2‐based symmetric MSCs. Benefitting from its ultrafast response, the 3D MSC exhibits superiority in terms of the phase angle (−66°), areal capacitance (1400 µF cm−2), and time constant (0.6 ms) at an alternating‐current (AC) frequency of 120 Hz. By using the 3D MSC as a line‐filtering capacitor in a real circuit, the AC signal is effectively smoothed with small residual ripples (≈1.35 mV). Additionally, the device achieves excellent performance in an all‐solid‐state form. [ABSTRACT FROM AUTHOR]

In this Letter, we demonstrate heteroepitaxial α-Ga2O3 MOSFETs using an aluminum scandium nitride (AlScN) ferroelectric gate stack. Owing to ferroelectric effects, α-Ga2O3 MOSFETs with the AlScN/HfO2 gate stack (FGFET) exhibited enhanced electrical performance compared with a HfO2 gate dielectric (IGFET) for variable gate–drain lengths (10, 15, 20 μm). A remnant polarization value of the AlScN deposited on a HfO2 layer was measured to be about 30 μC/cm2. The subthreshold swing (SS) and field-effect mobility (μFE) of IGFET was extracted at 1814 mV/dec and 13.9 cm2/V s, respectively. However, the FGFET exhibits a reduced SS of 552 mV/dec with enhanced μFE of 42.7 cm2/V s owing to the negative capacitance of the ferroelectric AlScN. Furthermore, a lateral figure-of-merit of 17.8 MW/cm2 was achieved for the FGFET, far surpassing the 8.3 MW/cm2 of the IGFET. The proposed ferroelectric AlScN/HfO2 stack can be a promising gate structure for improving both transfer and breakdown characteristics in heteroepitaxial α-Ga2O3 power devices. [ABSTRACT FROM AUTHOR]

The most significant challenge associated with micro‐light‐emitting‐diode (micro‐LED) displays, which are anticipated to be the next generation of display technology, is the high manufacturing cost. In order to reduce manufacturing costs, it is essential to improve yield. Improving the manufacturing yield of them necessitates the evaluation of micro‐LED chips prior to their installation onto substrates. However, the microsize and large quantity of these chips renders inspection difficult with conventional inspection methods. Herein, we propose a method for inspecting micro‐LED chips by measuring the voltage generated between the anode and cathode due to the photovoltaic effect using a developed proximity capacitance image sensor. As this inspection method does not require the use of probe pins to contact LED electrodes, it enables simultaneous inspection of multiple chips in a short time without causing any damage to the electrodes. In this paper, an experimental system equipped with this sensor was developed to demonstrate the basic measurement principle. Moreover, we demonstrated that more than 50,000 micro‐LED chips with a size of 60 μm × 34 μm can be simultaneously inspected in approximately 2 s. [ABSTRACT FROM AUTHOR]

In this study, microelectrical discharge machining (μEDM) is used for drilling microholes on a thin sheet of Ti Grade 2 alloy of thickness 50 μm using a tungsten carbide (WC) microtool of diameter 470 μm. The main focus of the study is to understand the electrical and nonelectrical μEDM parameters on the accuracy, precision, and machining efficiency of drilled holes. The controllable process factors such as capacitance, voltage, tool rotation, and feed rate are considered when conducting the experiments based on a Taguchi L16 orthogonal array. The main effect and interaction contour plots have been prepared to investigate the influence of the process parameters on the response measures like material removal rate, overcut, circularity, and taper angle of the drilled holes. Analysis of variance (ANOVA) has been carried out to study the percentage contribution and significance of each process parameter on the performance measures. The micrographic images reveal the quality of the profiles and edges of the drilled holes. Further, the Overall Evaluation Criterion (OEC) is applied for multiparameter optimization. [ABSTRACT FROM AUTHOR]

In a modular multilevel converter (MMC) system, the sub‐module capacitors account for a large proportion of the cost, volume, and weight. This paper proposed a method to reduce the total capacitance of MMC based on the combination of boosting the modulation index (m) and second‐harmonic circulating current injection (SCCI). A small amount of full‐bridge sub‐modules was added to conventional half‐bridge sub‐modules (HBSM) based MMC to form the hybrid MMC. The third‐harmonic voltage injection technology was used to increase the m of hybrid MMC without the common‐mode voltage injected on the ac‐side. An optimized SCCI method determined by m was introduced, which limited the root mean square (RMS) of arm current. An improved modulation approach is used to eliminate the coupling effect of third‐harmonic voltage injection and SCCI in boosting m, ensuring that the m increases to 1.15 with the optimized SCCI. Compared with conventional HBSM‐MMC, the proposed method reduced the total capacitance by approximately half when m = 1.15. A comprehensive comparison of different capacitance reduction methods was presented to demonstrate the cost and effect. Simulation and experiment verified the proposed method. [ABSTRACT FROM AUTHOR]

Purpose: In the measurement of liquid density and viscosity, the change of resonance parameters due to the parasitic parallel capacitance of resonator affects the measurement accuracy. To improve the accuracy, a method was proposed to compensate the parasitic parallel capacitance of resonator by adding an electrode. Design/methodology/approach: The new electrode (compensation electrode) was added into resonant sensor to make compensation capacitance. The closer the compensation capacitance was to the parasitic parallel capacitance, the better compensation was. The structural parameters of resonant sensor with the compensation electrode were determined by the simulation and experiment. Findings: The effect of this method was examined by the experiment. The relative errors of density and viscosity were less than 0.15, 0.5 % and standard deviations were less than 0.0004 g/cm3 and 0.005 mPas, respectively. Practical implications: The experimental results show that this method is valuable for the parasitic parallel capacitance compensation of immersed resonant sensor. Originality/value: This paper has not been published in other journals. [ABSTRACT FROM AUTHOR]

Needle-like CoO nanowires have been successfully synthesized by a facile hydrothermal process on an electrospun carbon nanofibers substrate. The as-prepared sample mesoporous CoO nanowires aligned vertically on the surface of carbon nanofibers and cross-linked with each other, producing loosely porous nanostructures. These hybrid composite electrodes exhibit a high specific capacitance of 1068.3 F g−1 at a scan rate of 5 mV s−1 and a good rate capability of 613.7 F g−1 at a scan rate of 60 mV s−1 in a three-electrode cell. The CoO NWs@CNF//CNT@CNF asymmetric device exhibits remarkable cycling stability and delivers a capacitance of 79.3 F/g with a capacitance retention of 92.1 % after 10,000 cycles. The asymmetric device delivers a high energy density of 37 Wh kg−1 with a power density of 0.8 kW kg−1 and a high power density of 16 kW kg−1 with an energy density of 23 Wh kg−1. This study demonstrated a promising strategy to enhance the electrochemical performance of flexible supercapacitors. [ABSTRACT FROM AUTHOR]

With its distinctive multiple electrochemical reaction, iron vanadate (FeV3O9.2.6H2O) is considered as a promising electrode material for energy storage. However, it has a relatively low practical specific capacitance. Therefore, using the low temperature sol–gel synthesis process, transition metal doping was used to enhance the electrochemical performance of layered structured FeV3O9.2.6H2O (FVO). According to this study, FVO doped with transition metals with larger interlayer spacing exhibited superior electrochemical performance than undoped FVO. The Mn-doped FVO electrode showed the highest specific capacitance and retention of 143 Fg−1 and 87%, respectively, while the undoped FVO showed 78 Fg−1 and 54%. [ABSTRACT FROM AUTHOR]

The Co3O4 nanowire@NiCo2O4 nanosheet hierarchical array was constructed on Ni foam using hydrothermal and annealing approaches in turn, from which a NiCo2O4 nanosheet could self-assemble on the Co3O4 nanowire. The structure and morphology of the Co3O4 nanowire@NiCo2O4 nanosheet hierarchical array were characterized via XRD, EDS, SEM, and FESEM, respectively. The electrochemical performance of the composite array was measured via a cyclic voltammetry curve, galvanostatic current charge–discharge, charge–discharge cycle, and electrochemical impedance and then compared with the Co3O4 nanowire. The results show that the Co3O4 nanowire@NiCo2O4 nanosheet hierarchical array could reach a high value of 2034 F g−1 at a current density of 2.5 A g−1. After 5000 galvanostatic charge–discharge cycles, the specific capacitance of the Co3O4 nanowire@NiCo2O4 nanosheet hierarchical array could still maintain 94.7% of the original value. Therefore, the Co3O4 nanowire@NiCo2O4 nanosheet hierarchical array would be a desirable electrode material for a high-performance supercapacitor. [ABSTRACT FROM AUTHOR]

The potential of electrochemical water splitting to tackle energy and environmental issues has garnered substantial interest. In the present work, an effective ZnS/In2Te3 has been constructed by hydrothermal support on a stainless‐steel strip and explored for oxygen evolution. The addition of ZnS modifies the band structure of In2Te3 and enhances its specific conductivity and capacitance on an intrinsic level, making rapid ion transportation. The optimized ZnS/In2Te3 displayed efficient oxygen evolution reaction (OER) performance with an overpotential of 228 mV and a Tafel slope of 111 mV dec−1 with cyclic activity up to 1000 cycles in 1 M KOH solution. ZnS/In2Te3 has a large surface area (28 m3g−1) and a charge capacitance of (.037 mF), according to studies using Brunauer–Emmett–Teller and double‐layer capacitance. Combining several strategies improves overall electrochemical performance of ZnS/In2Te3, making it a promising option for use in state‐of‐the‐art OER. [ABSTRACT FROM AUTHOR]

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This article presents a power-efficient DC-DC converter based on a switched-capacitor (SC) cell in power management systems supplied for fully integrated photovoltaic (PV) modules. These modules shall provide high-performance point-of-load voltage regulation. The primary objective of this study is to better utilize capacitance and switches by selecting a proper SC topology in order to improve the power efficiency of SC converters. A general steady-state performance model is investigated to optimize and compare a variety of SC DC-DC topologies. The investigation method relies on a charge-multiplier approach and considers the impact of area constraint on capacitors. To identify the most suitable topology for a given conversion ratio, the performance-limit metrics of SC converters are calculated. The analysis provides framework to determine optimum switch size and switching frequency for a two-phase 3:1 series–parallel converter for a target load current of 10 mA implemented on a 22 nm process technology. The results shows that a minimum of 250 MHz switching frequency is desirable for achieving a target efficiency greater than 85% while maintaining the minimum output voltage of 0.34 V. The analysis results are verified through MATLAB and PSpice-based simulations. [ABSTRACT FROM AUTHOR]

The antiferroelectric-ferroelectric phase transition is a basic principle that holds promise for antiferroelectric ceramics in high capacitance density nonlinear capacitors. So far, the property optimization based on antiferroelectric-ferroelectric transition is solely undertaken by chemical composition tailoring. Alternately, here we propose a phase transition engineering tactic by applying pulsed electric stimulus near the critical electric field, which finally results in ~54.3% enhancement and quick stabilization of capacitance density in Pb0.97La0.02(Zr0.35Sn0.55Ti0.10)O3 antiferroelectric ceramics. Ex-situ and in-situ structural characterizations show that electric stimuli can induce the charming successive structural evolution, including domain evolution from multidomain to monodomain state, and modulation period change from 7.49 to 7.73. Structure-property correlation indicates that the antiferroelectric-ferroelectric phase transition engineering mainly stems from the unexpected irreversible recovery of the modulated structures. The present findings would deepen the understanding of the structural phase transition and provoke composition-independent post-treatment property innovation in the incommensurate antiferroelectric materials and devices. The authors utilize the pulsed electric stimulus near the critical electric field to perform the antiferroelectric-ferroelectric phase transition engineering, realizing enhancement and quick stabilization of capacitance in antiferroelectrics. [ABSTRACT FROM AUTHOR]

Supercapacitors offer superior energy storage capabilities than traditional capacitors, making them useful for applications such as electric vehicles and rapid large‐scale energy storage. The energy storage performance of these devices relies on electrical double‐layer capacitance and/or pseudocapacitance from rapid reversible redox reactions. Metal–organic frameworks (MOFs) have recently emerged as a new class of electrode materials with promising supercapacitor performances and capacitances that exceed those of traditional materials. However, the comparison of the supercapacitor performance of a porous carbon and a state‐of‐the‐art MOF highlights a number of challenges for MOF supercapacitors, including low potential windows, limited cycle lifetimes, and poor rate performances. It is proposed that the well‐defined and tuneable chemical structures of MOFs present a number of avenues for improving supercapacitor performance. Recent experimental and theoretical work on charging mechanisms in MOF‐based supercapacitors is also discussed, and it is found that there is a need for more studies that elucidate the charge storage and degradation mechanisms. Ultimately, a deeper understanding will lead to design principles for realizing improved supercapacitor energy storage devices. [ABSTRACT FROM AUTHOR]

In an underground inductive power transfer (IPT), it is inevitable to produce the phenomenon of misalignment between the transmitter and the receiver, which will reduce the output current, voltage and output efficiency of the whole IPT system. Aiming to solve this problem, a universal hybrid coupler is proposed, which can still stabilize the output in the expected range and has the ability of anti-misalignment when the X and Z directions are misaligned. The coupler is composed of a BP coupler and Γ type network. The secondary edge of the coupler introduces a Γ network, which decouples the two main coils on the same side of the receiver from the auxiliary coil and reduces the complexity of the system. The coupler can effectively reduce the coupling fluctuation caused by physical movement between the downhole transmitting end and the receiving end, thereby ensuring the stable output of the coupler. As a widely used IPT system, it can access the rest of the circuit topology whose output is independent of the load and achieve misalignment-tolerant output. Finally, based on the proposed hybrid IPT coupler theory, a 500 W misalignment-tolerant coupler prototype was built, and the compensation topologies were configured as series–series (SS) and series/inductance/capacitance/capacitor (S/LCC) structures. When the X and Z direction is misaligned, the constant current and voltage independent of the load can be output by switching the compensation topology. The experimental results are the same as the theoretical analysis. [ABSTRACT FROM AUTHOR]

DC link capacitors (DCLCs) are key devices in converters. The relative humidity affects the performance of the elements of a DCLC. Currently, there are relatively few studies on the effect of relative humidity on the electrical characteristics of the elements of DCLCs during the production process. This study describes the effects and the control of the relative humidity in the production process. For this purpose, a DCLC component withstand voltage test platform and a DCLC component aging test platform were established. The voltage withstand tests were conducted during different processes and at different relative humidities, and life aging tests were conducted at different relative humidities and different storage times. The results show that after the winding and metal-spraying processes, the voltage withstand levels of the components stored at 30% RH, 60% RH, and 80% RH were very close to that of the components at 3000 VDC; after the heat-setting process, the voltage withstand levels of the components stored at 30% RH, 60% RH, and 80% RH showed a decreasing tendency compared with the level of the components at 3000 VDC. Regarding the samples, after the heat-setting process, stored at 30% RH and 60% RH for 24 h, 96 h, 168 h, 240 h, and 336 h and 2000 h of the aging tests, the capacitance decreases monotonically as the storage time is increased but never exceeds 3%, and the capacitance change decreases as the relative humidity increases. This study can provide important guidance for the humidity control of various processes in the production of DCLCs. [ABSTRACT FROM AUTHOR]

ABSTRACT The accurate emulation of the electrical impedance of biological tissues is crucial for the development and validation of bioimpedance measurement devices and algorithms. This paper describes a digitally controllable impedance emulator capable of reproducing values representative of tissue bioimpedance in user‐specified resistance, reactance, and frequency ranges up to 1 MHz. The presented solution uses a 2R‐1C impedance model to emulate the impedance characteristics of a biological tissue. Specific selection of each element value in this model is achieved using analog multiplexers with low Ron$$ {R}_{on} $$ resistance. A MATLAB algorithm was developed for value estimation using target impedance requirements. An example design to emulate impedance from 1 kHz to 1 MHz with 10 Ω$$ \Omega $$ to 400 Ω$$ \Omega $$ resistance and −45Ω$$ -45\Omega $$ maximum reactance is provided. The nonideal behavior of this design was evaluated and compared against experimentally collected impedance measurements. Deviations of <1% were observed between experimental and theoretical resistances for values >50Ω$$ >50\Omega $$ up to 100 kHz (with approximately 5% deviations up to 1 MHz) and reactance deviations were also <1% up to 10 kHz. High frequency deviations are attributed to the parasitic capacitance in the realization of the design. The experimental results validate the design approach and realization for low frequencies. Overall, the innovation of the proposed approach is the control of both resistance and reactance for emulating electrical impedance representative of biological tissues. [ABSTRACT FROM AUTHOR]

In this study, bismuth oxyfluoride (BiOF) nanostructures were synthesized using a microwave synthesis method at 150 °C, 175 °C, and 200 °C, which were denoted as BiOF-150, BiOF-175, and BiOF-200, respectively. Their morphological, structural, and electrochemical properties were studied using various techniques. Compared to BiOF-150 and BiOF-200, BiOF-175 exhibited a high specific capacity of 623.4 Fg−1 at a current density of 0.5 A g−1. Further, the material exhibited a capacitance retention of 77.4 % after 10000 cycles (at 5 A g−1), highlighting its high cycling stability. The BiOF-175 nanosheets exhibited good electrochemical performance, making them a viable choice for supercapacitor (SCs) applications. [ABSTRACT FROM AUTHOR]

In wafer testing, the test probe needs to contact the surface of the semiconductor wafer to measure electrical parameters such as resistance, capacitance, and current. The probe mark damage frequently occurs on the machine during wafer testing. This phenomenon causes inaccuracies in electrical parameter testing, significantly reducing the yield in IC packaging processes and resulting in substantial manufacturing cost losses. Therefore, this study proposed an effective probe mark damage detection and prediction method to prevent significant yield reduction due to inaccurate testing. This study uses importance analysis from random forests and correlation analysis to identify the critical parameters influencing probe mark damage. Introducing these parameters into a Sparse Transformer with hybrid normalization can successfully train an intelligent model for predicting the occurrence of probe mark damage. The model accurately predicts the probability of probe mark damage and promptly adjusts machine parameters to avoid inaccuracies in electrical parameter settings. The proposed approach can outperform other methods, achieving two very high accuracies of 95.1% (at room temperature) and 93.5% (at high temperature) and significantly reducing the occurrence of large-area probe mark damage. [ABSTRACT FROM AUTHOR]

The large size of the sub-module (SM) capacitor is a typical problem in traditional modular multilevel converter-type solid-state transformers (MMC-SSTs). The MMC-SST based on high-frequency link interconnection is an effective solution for achieving lightweight capacitance. This structure can help to eliminate the symmetric SM fluctuating power, thereby reducing the SM capacitance. In a three-phase interconnected MMC-SST with low capacitance, potential risks may arise during transient processes, especially in cases of three-phase voltage asymmetry, such as large fluctuations in the SM voltage and unstable DC bus voltage. Aiming to solve this problem, this article re-analyzes the internal power characteristics of the MMC-SST under asymmetric operation and re-derives the SM capacitance constraint suitable for different degrees of three-phase voltage asymmetry. The new SM capacitance constraint enhances the asymmetric voltage ride-through capability of the MMC-SST. The new capacitance constraint is higher than that in symmetric operation, but it still has significant advantages in capacitance compared with the traditional MMC-SST. [ABSTRACT FROM AUTHOR]

In a modular multilevel converter (MMC) system, the sub‐module (SM) capacitors account for a large proportion of cost, volume and weight. Increasing modulation index (m) is an effective method to reducing the capacitance. Traditional MMC based on half‐bridge SM (HBSM) cannot boosting m while the hybrid MMC composed of HBSMs and full‐bridge sub‐modules (FBSM) can increase the m. The negative voltage is required when hybrid MMC works at the boosted m, which is only provided by the FBSMs because the HBSMs cannot output negative voltage. Therefore, appropriate control strategies are needed to achieve the normal operation of hybrid MMC under boosted m. This paper presents a control method suitable for hybrid MMC with high m based on multi‐harmonic voltage injection. The m is increased to 1.41 with the proposed multi‐harmonic voltage injection. Compared with the HBSM‐MMC, the proposed method reduces the total capacitance by more than 32%. Boosting m also reduces the RMS and peak value of the arm current by 18%. A comprehensive comparison was presented to demonstrate the cost and effect. Simulation and experiment verified the proposed method. [ABSTRACT FROM AUTHOR]

MoS2 is widely reported as anode material for sodium‐ion batteries (SIBs). However, its ability to operate effectively across a wide temperature range and at high rates continues to pose fundamental challenges, limiting its further development. Herein, a monolayer Fe‐doped MoS2/N,O‐codoped C overlapping structure is designed and employed as an anode for wide‐temperature‐range SIBs. Fe doping imparts MoS2 electrode with zero bandgap characteristics, an increased interlayer spacing, and low sodium‐ion diffusion energy barriers across wide operation temperatures. Impressively, Fe atoms doped into the MoS2 lattice can be reduced to superparamagnetic Fe0 nanocrystals of ≈2 nm during conversion reactions. In situ magnetometry reveals that these Fe0 nanocrystals can be used as electron acceptor in the formation of space charge zones with Na+, thereby triggering strong spin‐polarized surface capacitance that facilitates fast sodium‐ion storage over a wide temperature range. Consequently, the designed MoS2 electrode demonstrates exceptional fast‐charging capability in half/full cells operating at −40–60 °C. This study provides novel perspectives on the utilization of heteroatom doping strategies in conversion‐type electrode material design and proves the effectiveness of spin‐polarized surface capacitance effect on enhancing sodium‐ion storage over a wide temperature range. [ABSTRACT FROM AUTHOR]

ZnWO4@NiCo2O4 core–shell nanosheet array composites are synthesized on nickel foam via a two-step hydrothermal method. The optimal conditions, including a Ni(NO3)2·6H2O to Co(NO3)2·6H2O molar ratio of 2 : 1, 12 hours reaction time, and 120 °C temperature, yield a specific capacitance of 875 C g−1 at 1 A g−1. The electrode also maintains 81.1% capacitance after 10 000 cycles. The material's performance is attributed to its core–shell structure, which enhances ion diffusion and electron transport. This study presents a viable approach for high-performance supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

Dynamic random-access memory (DRAM) has been scaled down to meet high-density, high-speed, and low-power memory requirements. However, conventional DRAM has limitations in achieving memory reliability, especially sufficient capacitance to distinguish memory states. While there have been attempts to enhance capacitor technology, these solutions increase manufacturing cost and complexity. Additionally, Silicon-based capacitorless memories have been reported, but they still suffer from serious difficulties regarding reliability and power consumption. Here, we propose a novel Schottky barrier memory (SBRAM), which is free of the complex capacitor structure and features a heterojunction based on bandgap engineering. SBRAM can be configured as vertical cross-point arrays, which enables high-density integration with a 4F2 footprint. In particular, the Schottky junction significantly reduces the reverse leakage current, preventing sneak current paths that cause leakage currents and readout errors during array operation. Moreover, the heterojunction physically divides the storage region into two regions, resulting in three distinct resistive states and inducing a gradual current slope to ensure sufficient holding margin. These states are determined by the holding voltage (Vhold) applied to the programmed device. When the Vhold is 1.1 V, the programmed state can be maintained with an exceptionally low current of 35.7 fA without a refresh operation. [ABSTRACT FROM AUTHOR]