Low Switching Voltage Research Articles

Versatile Cu2ZnSnS4-based synaptic memristor for multi-field-regulated neuromorphic applications.

Integrating both electrical and light-modulated multi-type neuromorphic functions in a single synaptic memristive device holds the most potential for realizing next-generation neuromorphic systems, but is still challenging yet achievable. Herein, a simple bi-terminal optoelectronic synaptic memristor is newly proposed based on kesterite Cu2ZnSnS4, exhibiting stable nonvolatile resistive switching with excellent spatial uniformity and unique optoelectronic synaptic behaviors. The device demonstrates not only low switching voltage (-0.39 ± 0.08V), concentrated Set/Reset voltage distribution (<0.08/0.15V), and long retention time (>104s) but also continuously modulable conductance by both electric (different width/interval/amplitude) and light (470-808nm with different intensity) stimulus. These advantages make the device good electrically and optically simulated synaptic functions, including excitatory and inhibitory, paired-pulsed facilitation, short-/long-term plasticity, spike-timing-dependent plasticity, and "memory-forgetting" behavior. Significantly, decimal arithmetic calculation (addition, subtraction, and commutative law) is realized based on the linear conductance regulation, and high precision pattern recognition (>88%) is well achieved with an artificial neural network constructed by 5 × 5 × 4 memristor array. Predictably, such kesterite-based optoelectronic memristors can greatly open the possibility of realizing multi-functional neuromorphic systems.

Vacancy-Engineered Nickel Ferrite Forming-Free Low-Voltage Resistive Switches for Neuromorphic Circuits.

Innovations in resistive switching devices constitute a core objective for the development of ultralow-power computing devices. Forming-free resistive switching is a type of resistive switching that eliminates the need for an initial high voltage for the formation of conductive filaments and offers promising opportunities to overcome the limitations of traditional resistive switching devices. Here, we demonstrate mixed charge state oxygen vacancy-engineered electroforming-free resistive switching in NiFe2O4 (NFO) thin films, fabricated as asymmetric Ti/NFO/Pt heterostructures, for the first time. Using pulsed laser deposition in a controlled oxygen atmosphere, we tune the oxygen vacancies together with the cationic valence state in the nickel ferrite phase, with the latter directly affecting the charge state of the oxygen vacancies. The structural integrity and chemical composition of the films are confirmed by X-ray diffraction and hard X-ray photoelectron spectroscopy, respectively. Electrical transport studies reveal that resistive switching characteristics in the films can be significantly altered by tuning the amount and charge state of the oxygen vacancy concentration during the deposition of the films. The resistive switching mechanism is seen to depend upon the migration of both singly and doubly charged oxygen vacancies formed as a result of changes in the nickel valence state and the consequent formation/rupture of conducting filaments in the switching layer. This is supported by the existence of an optimum oxygen vacancy concentration for efficient low-voltage resistive switching, below or above which the switching process is inhibited. Along with the filamentary switching mechanism, the Ti top electrode also enhances the resistive switching performance due to interfacial effects. Time-resolved measurements on the devices display both long- and short-term potentiation in the optimized vacancy-engineered NFO resistive switches, ideal for solid-state synapses achieved in a single system. Our work on correlated oxide forming-free resistive switches holds significant potential for CMOS-compatible low-power, nonvolatile resistive memory and neuromorphic circuits.

A novel multi-port high-gain bidirectional DC–DC converter for energy storage system integration with DC microgrids

Bidirectional converters have often been used in numerous applications like DC microgrids, renewable energy, hybrid energy storage systems, electric vehicles, etc. The paper proposes a novel multi-port high-gain (NMPHG) bidirectional DC–DC converter that supports DC microgrid (DC-MG) applications. The main contributions of the proposed converter are high step-up/step-down conversion gain, multiple input ports, lower switch voltage stress, and lower component count owing to the single converter with multiple input ports for DC microgrid applications. The detailed operational principle, analysis, and design considerations of proposed NMPHG bidirectional DC–DC converters are discussed. Furthermore, the loss analysis, detailed comparison with similar works, and efficiency analysis with non-modalities during forward power flow (LV to HV) and reverse power flow (HV to LV) modes are presented. The efficiency of the proposed converter is found to be 93.8% in forward power flow and 92.9% in reverse power flow modes at rated power. Finally, a hardware prototype of the proposed NMPHG bidirectional DC–DC converters is implemented with 100 W in FPF mode and 200 W in RPF mode with a TMS320F28335 processor and validated with theoretical counterparts.

Cu/MgO-based resistive random access memory for neuromorphic applications

Resistive Random Access Memory (ReRAM) is considered to be a suitable candidate for future memories due to its low operating voltage, fast access speed, and the potential to be scaled down to nanometer range for ultra-high-density storage. In addition, its ability to retain multi-level resistance states makes it suitable for neuromorphic computing applications. In this paper, we report the resistive switching performance of Cu/MgO/Pt ReRAM. Repetitive resistive switching transitions with low switching voltages (around 1 V), 102 storage windows, and multi-level memory capabilities have been obtained. Biological synaptic plasticity behavior, such as long-duration potentiation/depression and paired-pulse facilitation, has been realized by the Cu/MgO/Pt ReRAM. The simulation of convolutional neural network for handwritten digit recognition is carried out to evaluate its potential application in neuromorphic systems. Finally, the conduction mechanism of the device is studied, and a resistive switching model based on Cu conducting filaments is proposed according to the dependence of I–V results on temperature and electrode size as well as the element distribution in the device. These findings indicate the potential of Cu/MgO/Pt device as high-performance nonvolatile memories and its utilization in future computer systems and neuromorphic computing.

Interface engineering for facile switching of bulk-strong polarization in Si-compatible vertical superlattices

Ferroelectric thin films incorporating different compositional layers have emerged as a promising approach for enhancing properties and performance of electronic devices. In recent years, superlattices utilizing various interactions between their constituent layers have been used to reveal unusual properties, such as improper ferroelectricity, charged domain walls, and negative capacitance in conventional ferroelectrics. Herein, we report a symmetry scheme based on the interface engineering in which the inherent cell-doubling symmetry allowed atomic distortions (phonons) in any vertically aligned superlattice activate novel interface couplings among atomic distortions of different symmetries and fundamentally improve the ferroelectric properties. In a materialized case, the ionic size difference between Hf4+ and Ce4+ in the HfO2/CeO2 (HCO) ferroelectric/paraelectric superlattice leads to these couplings. These couplings mitigate the phase boundary between polar and non-polar phases, and facilitate polarization switching with a remarkably low coercive field (Ec\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${E}_{c}$$\\end{document}) while preserving the original magnitude of the bulk HfO2 polarization and its scale-free ferroelectric characteristics. We show that the cell-doubled distortions present in any vertical superlattice have unique implications for designing low-voltage ferroelectric switching while retaining bulk-strong charge storing capacities in Si-compatible memory candidates.

Pioneering Maintenance Strategies for Enhanced Reliability of Low Voltage Switchboards

This study highlights the critical need for rigorous maintenance protocols, focusing on routine inspections, preventative measures, and timely corrective actions. Low voltage switch panels (PHB-TR) are vital for ensuring the efficiency and reliability of electricity distribution systems. Through systematic analysis of existing maintenance procedures and field evaluations across diverse setups, the research confirms that structured maintenance not only mitigates the risk of failures but also significantly reduces workplace accidents. The findings advocate for strict adherence to standard operating procedures and improved coordination among technicians, suggesting these strategies as global standards for enhancing the safety and functionality of electrical distribution networks. Highlights: Proper maintenance ensures optimal performance and reduces the risk of system failure. Adherence to applicable SOPs is crucial to prevent work accidents. Coordination and adherence to job distribution streamline work execution. Keywords: PHB-TR Maintenance, Split Switch Panel Maintenance, Low Voltage Split Switch Board

Phase Shift Angle Segmentation Modulation for Soft-Switching Medium-Voltage DAB Converter With Series-Connected SiC MOSFETs

Medium voltage (MV) dual active bridge (DAB) converter with series-connected SiC MOSFETs (S-SiC) is a promising solution for high power density isolated DC/DC converter. To improve the voltage sharing and reliability of S-SiC, relatively large snubber capacitors are connected in parallel with S-SiC. But this narrows the zero voltage switching-on (ZVS-on) range of S-SiC, and even reduces the efficiency and reliability of the entire converter. Adding non-optimized internal phase shift angle to the low-voltage (LV) side switching unit will result in excessive circulating power and still lead to low efficiency. In this paper, the phase-shift angle segmentation modulation (PSSM) scheme featuring soft-switching performance is proposed for a MV DAB converter with S-SiC. The proposed modulation scheme is based on a detailed derivation of the ZVS-on range and operation modes. Then, the changes in operation characteristics and the advantages brought by the proposed modulation scheme are analyzed in terms of transmission power, state transition process, switching current and device losses. Moreover, the introduced modes and ZVS-on characteristics are verified on the 4kV/1kV 200kW experimental prototype. As a result, the converter’s loss can be decreased by up to 75% under light load, validating the efficiency advantage of the proposed modulation scheme.

A single switch high gain multilevel boost converter with switched inductor topology for photovoltaic applications

This paper proposes a new transformer-less single-switch high-gain dc-dc converter for solar power systems. The suggested converter is created by supplementing the conventional boost converter with a switched inductor cell plus a voltage multiplier stage. The converter has several benefits, including a high voltage conversion ratio, reduced voltage stress on semiconducting switches and diodes, a reduction in the need for gate drivers because only one switch is used, as well as constant input current to prolong the lifespan of the photovoltaic cell. The analytical waveforms of the recommended converter can be seen in the continuous conduction mode (CCM). The analysis of voltage stress is done. In the presence of parasitic components, increased voltage gain and efficiency were also obtained.The proposed high-gain converter topology is compared to recently published high-gain converter topologies in terms of performance. Using PSIM, a high-gain dc-dc converter's performance is studied and analysed with regard to its low switching voltage stress. The suggested converter is successful in stepping up 20V to 400V at 160W power capacity, while offering a continuous input source current at 95% efficiency.

Broadband Silver Ribbon-Embedded Graphene and h-BN Optical Modulator With High Modulation Depth and Extinction Ratio and Low Switching Voltage

Broadband Silver Ribbon-Embedded Graphene and h-BN Optical Modulator With High Modulation Depth and Extinction Ratio and Low Switching Voltage

Analysis of Power Quality in Low Voltage Switch Panels in Real-Time Based on IoT Using the Fuzzy Logic Method

This far power quality analysis from the PHBTR monitoring system is still done manually. This condition creates several challenges in efficiency and accuracy in detecting and responding to changes in PHBTR power quality. With manual processes, collecting and analyzing data related to power quality can be time consuming, and there is the potential for delays in identifying disturbances or anomalies that could affect PHBTR performance. Therefore, in this research an innovative step was taken by applying the fuzzy logic method to simplify and increase the accuracy of automatic power quality analysis. From the analysis results, it was found that the power quality at the MCC4, GRL2, and CKG116 substations when viewed from voltage, current, frequency, and temperature, the three substations were at normal indications (91.32) and in good condition (76.32). However, the load balance quality of the three substations is still not balanced with load imbalance percentages of 110%, 52% and 17% respectively. This is because there are consumers in one phase using higher power than consumers in another phase, so a load imbalance will occur. This can be caused by differences in the use of electrical equipment or loads on each phase. Through this effort, it is hoped that significant improvements in the efficiency and responsibility of the PHBTR monitoring system can be achieved

Switchable Optical Properties of Dyes and Nanoparticles in Electrowetting Devices.

The optical properties of light-absorbing materials in optical shutter devices are critical to the use of such platforms for optical applications. We demonstrate switchable optical properties of dyes and nanoparticles in liquid-based electrowetting-on-dielectric (EWOD) devices. Our work uses narrow-band-absorbing dyes and nanoparticles, which are appealing for spectral-filtering applications targeting specific wavelengths while maintaining device transparency at other wavelengths. Low-voltage actuation of boron dipyromethene (BODIPY) dyes and nanoparticles (Ag and CdSe) was demonstrated without degradation of the light-absorbing materials. Three BODIPY dyes were used, namely Abs 503 nm, 535 nm and 560 nm for dye 1 (BODIPY-core), 2 (I2BODIPY) and 3 (BODIPY-TMS), respectively. Reversible and low-voltage (≤20 V) switching of dye optical properties was observed as a function of device pixel dimensions (300 × 900, 200 × 600 and 150 × 450 µm). Low-voltage and reversible switching was also demonstrated for plasmonic and semiconductor nanoparticles, such as CdSe nanotetrapods (abs 508 nm), CdSe nanoplatelets (Abs 461 and 432 nm) and Ag nanoparticles (Abs 430 nm). Nanoparticle-based devices showed minimal hysteresis as well as faster relaxation times. The study presented can thus be extended to a variety of nanomaterials and dyes having the desired optical properties.

Two-Switch Ultrahigh Step-Up DC–DC Converterer With Low Input Current Ripple and Low Switch Voltage Stress

Two-Switch Ultrahigh Step-Up DC–DC Converterer With Low Input Current Ripple and Low Switch Voltage Stress

Energy-efficient resistive switching synaptic devices based on patterned Ag nanotriangles with tunable gaps fabricated using plasma-assisted nanosphere lithography.

The development of synaptic devices featuring metallic nanostructures with brain-analog hierarchical architecture, capable of mimicking cognitive functionalities, has emerged as a focal point in neuromorphic computing. However, existing challenges, such as inconsistent and unpredictable switching, high voltage requirements, unguided filament formation, and detailed fabrication processes, have impeded technological progress in the domain. The present study addresses some of these challenges by leveraging periodic nanostructures of Ag fabricated via plasma-assisted nanosphere lithography (NSL). The triangular nanostructures with a preferred orientation offer enhanced localized electric fields, facilitating low voltage electromigration at the sharp edges to guide predictive filament formation. A thorough investigation into gap control between the nanostructures through oxygen plasma treatment enables the attainment of an optimized low switching voltage of 0.86 V and retention at an ultra-low current compliance of 100 nA. The optimized device consumes low power, typically in the fJ range, akin to biological neurons. Furthermore, the device showcases intriguing synaptic characteristics, including controlled transition from short- to long-term potentiation, associative learning, etc., projecting its potential in perceptive learning, memory formation, and brain-inspired computing. COMSOL Multiphysics simulation, supported by ex situ electron microscopic imaging, confirms the controlled and predictable filament formation facilitated by electric field enhancement across the strategic nanostructures. Thus, the work highlights the potential of NSL-based cost-effective fabrication techniques for realizing efficient and biomimetic synaptic devices for neuromorphic computing applications.

Bipolar Resistive Switching in 2D MoSe2 Grown by Atmospheric Pressure Chemical Vapor Deposition.

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) are highly promising nanomaterials for various electronic devices such as field-effect transistors, junction diodes, tunneling devices, and, more recently, memristors. 2D MoSe2 stands out for having high electrical conductivity, charge carrier mobility, and melting point. While these features make it particularly appropriate as a switching layer in memristive devices, reliable and scalable production of large-area 2D MoSe2 still represents a challenge. In this study, we manufacture 2D MoSe2 films by atmospheric-pressure chemical vapor deposition and investigate them on the atomic scale. We selected and transferred MoSe2 bilayer to serve as a switching layer between asymmetric Au-Cu electrodes in miniaturized crossbar vertical memristors. The electrochemical metallization devices showed forming-free, bipolar resistive switching at low voltages, with clearly identifiable nonvolatile states. Other than low-power neuromorphic computing, low switching voltages approaching the range of biological action potentials could unlock hybrid biological interfaces.

Highly flexible and robust HfOx-based memristor for wearable in-memory computing

Metal oxide-based memristors usually exhibit robust resistive switching characteristics but poor mechanical tolerance, limiting their applications in wearable intelligent electronics. Here, we report a highly flexible and robust hafnium oxide-based memristor by using the ultrathin substrate for wearable in-memory computing. The fabricated memristor can display reliable resistive switching behaviors, including low switching voltage, good endurance, and excellent uniformity, under an extremely bending state with the radius of 0.8 mm. The mechanical behavior of the flexible memristor with varying substrate thickness is systematically analyzed using the finite element method. Moreover, typical synaptic plasticity including long-term potentiation and long-term depression was verified under the extremely bending state. Based on the highly flexible and robust memristor device, a three-layer neural network was constructed using a software simulator, achieving a recognition accuracy of 90.49% for handwritten digit recognition under the bending state. These results demonstrate our robust memristor synapse shows high mechanical flexibility, paving a promising way to realizing wearable in-memory computing.

A novel non-isolated step-down converter with low switch voltage stress

ABSTRACT This article is aimed at introducing a novel non-isolated step-down converter with superior advantages including reduced voltage stress on switching, enhanced efficiency as well as reduced number of required components. Improved distribution of voltage among several switches mitigates the stress exerted upon individual switches, thereby inflicting reduced voltage MOSFETS with smaller ON resistance. To show the superiority of the introduced converter over other converters of this kind through comparison, ON-OFF switching operations of two switches are performed under ZVS conditions, and as a result, a reduced switching loss is observed which is a proof for optimised efficiency. Finally, the design formula and simulations of the converter operating modes are discussed.

Flexible SnO2–MoS2 based memristive device exhibiting stable and enhanced memory phenomenon

Flexible non-volatile memory devices have been gaining interest in expanding the digital data storage world. Due to the burgeoning advancement in the healthcare industry, the Internet of Things, and wearable electronics, the demand for ultra-thin, low-power, and flexible memory is increasing. Further, the advancement of synthesis procedures for two-dimensional nanomaterials having better optical, electrical, and mechanical strength with flexibility has fuelled the flexible memory device area, as commonly used flash memory is approaching its physical limit. In this context, the present work reports the flexible resistive switching memory device based on pure molybdenum disulfide (MoS2) and tin oxide (SnO2) based nanocomposite powder synthesized using the simple hydrothermal process. The nanocomposite formation was characterized using x-ray diffraction and Raman spectroscopic techniques. The memory device was fabricated by spin-coating the pure MoS2, pure SnO2, and MoS2–SnO2 nanocomposite film over the ITO-PET flexible substrate. The device was completed by thermally evaporating the thin Al layer through a shadow mask. It was found that MoS2–SnO2 based memory devices exhibited improved switching performance having a higher I ON/I OFF ratio, and lower switching voltage in comparison to pure MoS2 and pure SnO2-based devices (I ON/I OFF ratio ∼100, V = 0.5 V). Furthermore, to check the stability and cyclic performance of the fabricated device, the retention and endurance test was also performed, and the MoS2–SnO2 device retained the HRS and LRS states up to 2 × 103s and showed stable performance up to 100 switching cycles without much degradation, respectively. It should be mentioned that the presently proposed ReRAM device based on SnO2 and MoS2 with flexible and low-power features had excellent potential for use in the wearable device industry.

MoS2-Based Memristor: Robust Resistive Switching Behavior and Reliable Biological Synapse Emulation.

Memristors are recognized as crucial devices for future nonvolatile memory and artificial intelligence. Due to their typical neuron-synapse-like metal-insulator-metal(MIM) sandwich structure, they are widely used to simulate biological synapses and have great potential in advancing biological synapse simulation. However, the high switch voltage and inferior stability of the memristor restrict the broader application to the emulation of the biological synapse. In this study, we report a vertically structured memristor based on few-layer MoS2. The device shows a lower switching voltage below 0.6 V, with a high ON/OFF current ratio of 104, good stability of more than 180 cycles, and a long retention time exceeding 3 × 103 s. In addition, the device has successfully simulated various biological synaptic functions, including potential/depression propagation, paired-pulse facilitation (PPF), and long-term potentiation/long-term depression (LTP/LTD) modulation. These results have significant implications for the design of a two-dimensional transition-metal dichalcogenides composite material memristor that aim to mimic biological synapses, representing promising avenues for the development of advanced neuromorphic computing systems.

A High-Efficiency Single-Stage Isolated Sepic-Flyback AC–DC Led Driver

Regulating LED current and voltage is critical to maintaining a constant luminous flux in AC- or DC-powered LED lighting circuits. Today, users require constant current drivers that can provide a wide range of output voltages to drive different numbers of series-connected LED arrays. This work proposes an LED driver by combining an isolated SEPIC converter operating in the continuous conduction mode (CCM) and a modified Vienna rectifier. The proposed LED driver offers a single-switch control structure by adding a Vienna rectifier to the integrated SEPIC-FLYBACK converter. This driver structure provides many advantages over traditional bridge rectifier structures. The prototype circuit was tested in an 18 W continuous current mode (CCM) to verify its feasibility. As a result of the values obtained from both simulation and prototype circuit models, it has been shown to provide many of the following advantages: 95% high efficiency, high reliability, 4% low total harmonic distortion, 97% high power factor, and 70 V low switching voltage. This work meets class C 3-2 and IEC 61000 standards.

New concept of two-cascade energy compression systems based on drift step recovery diodes

A new concept of effective high-voltage nanosecond pulse generators based on two compression cascades of drift step recovery diodes (DSRDs) is presented. The main advantage of the proposed approach arises from the decoupling of the operation cycles of DSRD cascades while using a single primary switch. This greatly improves the overall efficiency of the system. The first DSRD cascade operates with low pulse current densities. Its operation cycles can be extended resulting in an increase of the compression factor and pulse energy, whereas the loss level is kept at a minimum. The second DSRD cascade operates with high current densities, but the duration of its cycles can be chosen much shorter which ensures good efficiency too. Furthermore, an extension of the working cycle of the first DSRD cascade makes the requirement for the primary switch milder so that even relatively slow low-voltage switches can be employed.