Low Switching Voltage Research Articles

Write-once-read-many-times memory device based on Pt/BiFeO3/LaNiO3 heterostructures

Nonvolatile memory devices based on resistive switching effects are promising candidates for next generation high performance nonvolatile data storage. Here, we report the write-once-read-many-times (WORM) resistive switching behavior for the first time in Pt/BiFeO3/LaNiO3 heterostructures. BiFeO3 thin films with (100) preferred orientation have been prepared by RF magnetron sputtering combined with annealing at temperature higher than 600 ℃, and show excellent WORM resistive switching behaviors with data retention for>3600 s and reliable endurance for>1000 cycles. The devices with BiFeO3 annealed at 650 ℃ exhibit extremely high ON/OFF ratio (>3 × 104) and low switching voltage (∼3 V) due to the high quality of BiFeO3 thin films. The observed resistive switching behavior is attributed to the formation of permanent conducting filaments that composed of oxygen vacancies. These results demonstrate that BiFeO3 is promising for novel WORM memory device applications.

Reconfigurable Low-Voltage Hexagonal Boron Nitride Nonvolatile Switches for Millimeter-Wave Wireless Communications.

Recently, nonvolatile resistive switching memory effects have been actively studied in two-dimensional (2D) transition metal dichalcogenides and boron nitrides to advance future memory and neuromorphic computing applications. Here, we report on radiofrequency (RF) switches utilizing hexagonal boron nitride (h-BN) memristors that afford operation in the millimeter-wave (mmWave) range. Notably, silver (Ag) electrodes to h-BN offer outstanding nonvolatile bipolar resistive switching characteristics with a high ON/OFF switching ratio of 1011 and low switching voltage below 0.34 V. In addition, the switch exhibits a low insertion loss of 0.50 dB and high isolation of 23 dB across the D-band spectrum (110 to 170 GHz). Furthermore, the S21 insertion loss can be tuned through five orders of current compliance magnitude, which increases the application prospects for atomic switches. These results can enable the switch to become a key component for future reconfigurable wireless and 6G communication systems.

Low-voltage electro-optic switching and modulation of second harmonic generation in lithium niobate resonant waveguide gratings assisted by quasi-BICs

We numerically investigate the low-voltage electro-optic (EO) switching at a telecommunication wavelength and modulation of second harmonic generation (SHG) in lithium niobate (LN) resonant waveguide gratings (RWGs) working at quasi-bound states in the continuum (BICs). The external applied voltage V0 = 0.4 V can realize the transmission changing from near zero at V0 = 0 to 70 % in the feasible RWGs nanostructure at quasi-BICs wavelength under both TM-and TE-polarization. The tuning efficiency, i.e. the shift of resonance wavelength at external per-voltage, arrives up to 121 pm/V and 56 pm/V under TM- and TE-polarization, respectively. Besides the switching of linear transmission, SHG from the LN RWGs is also effectively modulated by external voltages. Several orders of magnitude change in SHG conversion efficiency are achieved for the external voltage varying from V0 = 0 V to 1 V. The low-voltage switching, high tuning efficiency and dramatical modulation of SHG are ascribed to the ultra-high Q-factor at quasi-BICs which is sensitively affected by the refractive index of LN based on EO effect. The results show that the LN RWGs nanostructure working at quasi-BICs is promising for the application in high-performance EO linear and nonlinear devices.

A Single-Stage Bimodal Transformerless Inverter with Common-Ground and Buck-Boost Features

This paper proposes a single-phase, single-stage common-ground inverter with a non-electrolytic capacitor and buck-boost ability. The proposed single-stage inverter is employed by a boost stage DC-DC converter and bimodal circuit, which makes it satisfactory for PV systems with a wide input voltage range and lower switch voltage stress. The leakage current of the proposed single-stage inverter can effectively suppress because the parasitic capacitor between the PV panel and the ground is shortened. In addition, the proposed single-stage inverter does not include electrolytic capacitors, which reduces the equivalent series resistance of electrolytic capacitors and also the size of the inverter system. The topology, operating principle, and PWM control method of the proposed single-stage inverter are given. The design guidelines of components and comparative studies of the proposed single-stage inverter are provided. A 500 W laboratory prototype of the proposed single-stage inverter is built to verify the correctness of the simulation and theoretical analysis.

Rational design of a Ru(II) complex with a donor-acceptor-donor structure for organic resistive memory devices.

A novel Ru(II) complex with a donor-acceptor-donor (D-A-D) ligand was designed and synthesized to prepare organic memory devices. The fabricated Ru(II) complex-based devices exhibited obvious bipolar resistance switching behavior with a low switching voltage (∼1.13 V) and a large ON/OFF ratio (105). The dominant switching mechanism can be explained by the distinct charge-transfer states endowed by the interaction between metals and ligands, which is verified by density functional theory (DFT) calculations. Excitingly, the device displays a much lower switching voltage than most of the previously reported metal complex based memory devices due to the intense intramolecular charge transfer caused by the strong built-in electric field in D-A systems. This work not only reveals the potential of the Ru(II) complex in resistive switching devices, but also provides new inspiration to manipulate the switching voltage at the molecular level.

Solution-based in situ deposition of Sb2S3 from a single source precursor for resistive random-access memory devices

A one-step, scalable, reproducible, low-temperature, and in situ solvothermal deposition method has been established for the growth of Sb2S3 on FTO using [Sb{S2P{O(Pr)2}3] precursor. The Ag/Sb2S3/FTO device demonstrated low operating voltage and excellent resistive switching characteristics.

Low-voltage resistive switching characteristics of nano-bowl-like NiO arrays

我们利用单层胶体球自组装模板结合电化学沉积和磁控溅射方法在覆盖Pt导电层的白云母衬底上制备了NiO纳米碗状阵列(nano-bowl-like NiO array, 简称nb-NiO). 每个NiO纳米碗高约450 nm, 碗口直径约450 nm, 碗底厚约150 nm, 在Pt导电层上密排形成二维阵列. 在nb-NiO上覆盖厚约20 nm的HfO2薄膜层, 然后制备Ag或Pt点电极形成Ag(Pt)/HfO2/nb-NiO/Pt堆栈结构器件. 器件在小于± 0.4 V的翻转电压下即在高低电阻态之间周期性可逆跳变, 表现出良好的电阻开关特性: 器件在高低电阻态之间翻转的时间< 8.7 μs; 初始高/低电阻比值约为10^4, 连续测试1500个周期后, 高/低电阻值比依然>10^3. 断电后, 器件稳定在高(低)电阻态的时间均>10^4 s. 纳米碗状阵列结构使得NiO厚度在150 ~ 450 nm内周期性连续变化; 由于氧空位导电细丝更易在厚度较小的纳米碗底部导通, 因此碗状阵列结构使得原本随机分布的氧空位导电细丝通道具有了局域有序性, 进而提高了器件电阻开关性能的稳定性. HfO2薄膜层降低了器件漏电流, 提高了器件的高/低电阻值比. Ag电极与氧离子的氧化还原反应加速了氧空位导电细丝通道的导通和断裂, 从而降低了翻转电压.

Research on temperature rise method of low voltage switch equipment

Research on temperature rise method of low voltage switch equipment

Hybrid Modular Multilevel Converters for High-AC/Low-DC Medium-Voltage Applications

With ever-increasing power-density requirements, technologies such as energy storage systems and electric-vehicles can benefit greatly from interfacing medium-voltage (MV)-AC grid like 13.8kV or 30kV using high-AC/low-DC voltage converter. Using modular high-AC/low-DC voltage converter can help increase power-density and efficiency, while reducing total conversion steps and providing flexibility. Full-bridge modular multilevel converters (FB-MMC) and solid-state transformers are existing solutions for such operations, but suffer from limitations of high semiconductor requirements, large submodule capacitors and/or many high-frequency transformers. Three new hybrid-MMC (HMMC) topologies are proposed in this paper as alternative solutions for such high-AC/low-DC voltage operations. Each of the three developed HMMCs utilizes a unique combination of low-frequency high-voltage switches and fast-switching low-voltage switch based submodules to generate multilevel-AC voltage. HMMCs are compared extensively to state-of-the-art FB-MMC and are shown to have semiconductor savings of over 27%, 38% lower submodule capacitor size, and 53% lower losses for 13.8-kV-AC/6-kV-DC operation. Due to these benefits like higher efficiency, significantly smaller submodule capacitance requirements, and fewer semiconductors, HMMCs can be an excellent option for high-AC/low-DC applications. Practical considerations like snubber and DC split-capacitor requirement are also elaborated for developing and commercializing HMMCs. Comparison results are verified using a 17.5 kW three-phase MV laboratory prototype.

Моделирование потерь мощности в контактных системах низковольтных коммутационных аппаратов

The article studies the dependences of active power losses in contacts and contact systems of circuit breakers, contactors and magnetic starters on the main parameters of electrical equipment. Models of functional dependences of active power losses on nominal current for low-voltage switching devices of some manufacturers are developed. Approximation functions of these characteristics have been compiled and the value of determination coefficient of the obtained functions of active losses and approximation error have been calculated. Graphical dependences of the investigated parameters of low-voltage equipment are presented.

Research on the Coordination Suppression Strategy of Neutral Point Potential and Common Mode Voltage for NPC Three-Level Inverter

A Neutral Point Clamped (NPC) type three-level inverter has the advantages of a low switch voltage and a high-quality output waveform. However, there are inherent problems, such as neutral point potential asymmetry and common mode interferences, which easily affect the symmetry of the three-phase output voltage and the safe operation of the inverter. Firstly, according to the different modulation degrees, the fluctuation of midpoint potential can be suppressed by adding an action time correction factor to the traditional space vector pulse-width (SVPWM) modulation strategy and virtual space vector pulse-width (VSVPWM) modulation strategy, respectively. Secondly, considering the suppression of common mode voltage, a new virtual space vector pulse-width (NVSVPWM) modulation strategy is proposed, which uses a set of new vector synthesis methods. Finally, the simulation and experiment prove that the NVSVPWM strategy with an action time correction factor can suppress the fluctuation of the neutral point potential and common mode voltage at the same time, and the effect is significant.

A low-power Si:HfO2 ferroelectric tunnel memristor for spiking neural networks

As key components of the human brain's neural network, synapses and neurons are important processing units that enable highly complex neuromorphic systems. Spiking neural network (SNN) is more powerful and efficient in terms of neuromorphic computing. Moreover, memristor-based neuromorphic computers can implement neural network algorithms more effectively than conventional hardware. However, the investigation on spiking neural network (SNN) based neuromorphic computing is still in the exploratory stage. Herein, a SNN based on ferroelectric Si:HfO2 film (∼ 6.8 nm) memristor was realized. The Si:HfO2-based memristor exhibits lower switching voltage (1.55/− 1.50 V) and super low power consumption (∼ 32.65 fJ). Additionally, it also shows superior conductance tunability and reliable realization of multiple synaptic functions. Especially, the highly linear conductance modulation of the Si:HfO2-based memristor results in a high accuracy of ∼ 96.23 % for handwritten digits. Spatiotemporal model recognition and unsupervised synaptic weight update functions were successfully implemented with the SNN constructed by these synaptic devices and artificial neuron models, which demonstrates the excellent adaptability and versatility of this SNN and paves the way for future neural network studies.

Forming-Free Tunable Analog Switching in WOx/TaOx Heterojunction for Emulating Electronic Synapses.

In this work, the sputtered deposited WOx/TaOx switching layer has been studied for resistive random-access memory (RRAM) devices. Gradual SET and RESET behaviors with reliable device-to-device variability were obtained with DC voltage sweep cycling without an electroforming process. The memristor shows uniform switching characteristics, low switching voltages, and a high RON/ROFF ratio (~102). The transition from short-term plasticity (STP) to long-term potentiation (LTP) can be observed by increasing the pulse amplitude and number. Spike-rate-dependent plasticity (SRDP) and paired-pulse facilitation (PPF) learning processes were successfully emulated by sequential pulse trains. By reducing the pulse interval, the synaptic weight change increases due to the residual oxygen vacancy near the conductive filaments (CFs). This work explores mimicking the biological synaptic behavior and further development for next-generation neuromorphic applications.

Intelligent Detection Algorithm of Medium and Low Voltage Switch Performance Based on the Improved K-means Clustering

The performance of medium and low voltage switches will directly affect the reliability of medium and low voltage distribution networks. The medium and low voltage switch algorithm’s failure form is mainly mechanical. In order to realize its intelligent detection, a medium and low voltage switch detection algorithm based on the improved K-means clustering algorithm is proposed. Optimizing the algorithm’s clustering center selection establishes a model of the switch working state under different vibration signals and an intelligent detection algorithm for medium and low voltage switches with intelligent judgment, adaptive adjustment, and remote fault diagnosis. Experiments show that: the detection algorithm of the medium and low voltage switch controller based on the improved K-means algorithm can more accurately identify the fault of the switch algorithm according to the vibration signals, which provides a new idea for the fault identification and monitoring of the medium and low voltage switch.

Flexible Memristor Devices Using Hybrid Polymer/Electrodeposited GeSbTe Nanoscale Thin Films.

We report on the development of hybrid organic-inorganic material-based flexible memristor devices made by a fast and simple electrochemical fabrication method. The devices consist of a bilayer of poly(methyl methacrylate) (PMMA) and Te-rich GeSbTe chalcogenide nanoscale thin films sandwiched between Ag top and TiN bottom electrodes on both Si and flexible polyimide substrates. These hybrid memristors require no electroforming process and exhibit reliable and reproducible bipolar resistive switching at low switching voltages under both flat and bending conditions. Multistate switching behavior can also be achieved by controlling the compliance current (CC). We attribute the switching between the high resistance state (HRS) and low resistance state (LRS) in the devices to the formation and rupture of conductive Ag filaments within the hybrid PMMA/GeSbTe matrix. This work provides a promising route to fabricate flexible memory devices through an electrodeposition process for application in flexible electronics.

Sub-volt switching of nanoscale voltage-controlled perpendicular magnetic tunnel junctions

Magnetic random-access memory (MRAM) based on voltage-controlled magnetic anisotropy in magnetic tunnel junctions (MTJs) is a promising candidate for high-performance computing applications, due to its lower power consumption, higher bit density, and the ability to reduce the access transistor size when compared to conventional current-controlled spin-transfer torque MRAM. The key to realizing these advantages is to have a low MTJ switching voltage. Here, we report a perpendicular MTJ structure with a high voltage-controlled magnetic anisotropy coefficient ~130 fJ/Vm and high tunnel magnetoresistance exceeding 150%. Owing to the high voltage-controlled magnetic anisotropy coefficient, we demonstrate sub-nanosecond precessional switching of nanoscale MTJs with diameters of 50 and 70 nm, using a voltage lower than 1 V. We also show scaling of this switching mechanism down to 30 nm MTJs, with voltages close to 2 V. The results pave the path for the future development and application of voltage-controlled MRAMs and spintronic devices in emerging computing systems.

Resistive Switching and Synaptic Behavior of Perovskite Lanthanum Orthoferrite Thin Film for Neuromorphic Computing

A resistance random access memory (RRAM), based on a metal oxide thin film with resistive switching behavior, has been explored as an emerging candidate for their application as nonvolatile memories, due to their various advantages, such as simple device configuration, long data retention, high switching speed, and low operating voltage. Various metal oxides have been explored for resistive switching applications including, e.g., binary and ternary compounds. Among all metal oxides, the perovskites have attracted considerable interest due to their potential to be used for information storage and neuromorphic application. In this work, we demonstrate stable bipolar resistive switching devices based on the sputtered LaFeO3 thin film on fluorine doped tin oxide (FTO)-coated glass with circular-shaped silver contacts. The memory performance of fabricated devices was characterized as a function of the thickness of the LFO thin layer. The resistive switching properties are investigated using macroscopic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}$ </tex-math></inline-formula> measurements, showing low-voltage switching with a high ON–OFF ratio ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\approx 300$ </tex-math></inline-formula> ) and long retention (≥9000 s). The fabricated devices demonstrate the stable, low voltage and high-speed switching. Furthermore, in this work, we demonstrate the synaptic behavior of the LFO thin-film memory devices, as it exhibits analog memory characteristics, potentiation, and depression.

Analysis and Modeling of a Single-Power-Source T-Type 7-Level Single-Phase DC-AC Inverter with Voltage Gain of 3

This paper proposes a novel T-type 7-level single-phase DC-AC inverter having a single input power source, self-balancing, and voltage gain of 3 along with low total harmonic distortion (THD). Since the structure of the proposed 7-level DC-AC inverter is symmetrical, the interchangeability of mass production can be easily achieved. In addition, because only one switch works for all time, the switch has quite low switching loss and voltage stress as well as the control being very easy. Furthermore, not only the proposed 7-level DC-AC inverter is analyzed in detail by the operating principle, but also the mathematical model for the adopted level-shift sinusoidal pulse width modulation (LS-SPWM) for this multilevel DC-AC inverter is successfully developed by using the well-known state averaging technique widely employed in the DC-DC converter. As a result, the required proportional-integral (PI) controller, used in the closed loop, can be designed systematically and easily. Eventually, the feasibility and effectiveness of the proposed inverter are verified by simulated and experimental results.

High-Performance Pockels Effect Modulation and Switching in Silicon-Based GaP/Si, AlP/Si, ZnS/Si, AlN/3C-SiC, GaAs/Ge, ZnSe/GaAs, and ZnSe/Ge Superlattice-On-Insulator Integrated Circuits.

We propose new a Si-based waveguided Superlattice-on-Insulator (SLOI) platforms for high-performance electro-optical (EO) 2 × 2 and N × M switching and 1 × 1 modulation, including broad spectrum and resonant. We present a theoretical investigation based on the tight-binding Hamiltonian of the Pockels EO effect in the lattice-matched undoped , , , , , , and wafer-scale short-period superlattices that are etched into waveguided networks of small-footprint Mach-Zehnder interferometers and micro-ring resonators to yield opto-electronic chips. The spectra of the Pockels r33 coefficient have been simulated as a function of the number of the atomic monolayers for “non-relaxed” heterointerfaces. The large obtained r33 values enable the SLOI circuit platforms to offer a very favorable combination of monolithic construction, cost-effective manufacturability, high modulation/switching speed, high information bandwidth, tiny footprint, low energy per bit, low switching voltage, near-IR-and-telecom wavelength coverage, and push-pull operation. By optimizing waveguide, clad, and electrode dimensions, we obtained very desirable values of the VπL performance metric, in the range of 0.062 to 0.275 V·cm, portending a bright future for a variety of applications, such as sensor networks or Internet of Things (IoT).

A New Topology of High-Efficiency DC-DC Hybrid Boost SEPIC Converter for PV Cell

This paper initiates a high-gain high efficiency step-up DC-DC converter based on Boost SEPIC (Single Ended Primary Inductor Converter) hybrid topology for photovoltaic application. Customarily DC-DC converter circuit is a widely used technique to improve the voltage level of solar cells. However, for low output voltage and low efficiency, they are not sufficient enough to provide expected outcomes. To defeat the conventional system a hybrid Boost SEPIC topology has been recommended with enhanced performance. The proposed design of the DC-DC converter circuit can provide a high voltage gain without decaying its overall performance. The modified converter topology is being worked by a single switch with low switching voltage stress over the semiconductor devices. The main edge of the proposed design is that it can perform efficiently without using any transformer, the combined design of Boost SEPIC topology increases the voltage gain much higher compared to the conventional Boost or SEPIC. The maximum Power Point Tracking (MPPT) algorithm is used to obtain maximum power from a photovoltaic source. MATLAB Simulink and PSIM software has analyzed the performance of the newly designed converter circuit thoroughly.