Fast Operation Research Articles

Investigation for AGZO RRAM using the RF Co-sputtering method

Recently, the Internet of Things (IOT) has rapidly developed, leading to the development of many smart devices. Moreover, artificial intelligence (AI) and 5G communication are successful, and the demand for high-performance memory is increasing. The emerging nonvolatile RRAM has many advantages, such as low power consumption, fast operation speed, simple structure and excellent scalability, compared with traditional memories; this is promising for complex computing and mass storage. Zinc oxide (ZnO) is a promising candidate for transparent conducting oxide (TCO) applications because of its abundance, high conductivity, low toxicity, and cost-effectiveness. It is currently used in various optoelectronic components including thin-film transistors (TFTs) and photodetectors. Notably, TCO has been increasingly used in the switching layers of random resistive access memory systems. In this paper, we intend to combine AGO with a large energy gap and ZnO with a high conductivity to prepare AGZO as a switching layer for RRAM by co-sputtering. By adjusting the oxygen flow ratio and power of co-sputtering, the AGZO RRAM exhibited high performance with more than 1400 switching cycles, 102–103 on/off ratio, and low operation voltage, and high- and low-resistance states could be maintained for more than 10,000[Formula: see text]s.

Sweet-spot operation of a germanium hole spin qubit with highly anisotropic noise sensitivity

Spin qubits defined by valence band hole states are attractive for quantum information processing due to their inherent coupling to electric fields, enabling fast and scalable qubit control. Heavy holes in germanium are particularly promising, with recent demonstrations of fast and high-fidelity qubit operations. However, the mechanisms and anisotropies that underlie qubit driving and decoherence remain mostly unclear. Here we report the highly anisotropic heavy-hole g-tensor and its dependence on electric fields, revealing how qubit driving and decoherence originate from electric modulations of the g-tensor. Furthermore, we confirm the predicted Ising-type hyperfine interaction and show that qubit coherence is ultimately limited by 1/f charge noise, where f is the frequency. Finally, operating the qubit at low magnetic field, we measure a dephasing time of T2*\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{2}^{* }$$\\end{document} = 17.6 μs, maintaining single-qubit gate fidelities well above 99% even at elevated temperatures of T > 1 K. This understanding of qubit driving and decoherence mechanisms is key towards realizing scalable and highly coherent hole qubit arrays.

Multilevel resistive switching in hydrothermally synthesized FeWO4 thin film-based memristive device for non-volatile memory application

The memristors offer significant advantages as a key element in non-volatile and brain-inspired neuromorphic systems because of their salient features such as remarkable endurance, ability to store multiple bits, fast operation speed, and extremely low energy usage. This work reports the resistive switching (RS) characteristics of the hydrothermally synthesized iron tungstate (FeWO4) based thin film memristive device. The detailed physicochemical analysis was investigated using Rietveld’s refinement, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) techniques. The fabricated Ag/FWO/FTO memristive device exhibits bipolar resistive switching (BRS) behavior. In addition, the devices exhibit negative differential resistance (NDR) at both positive and negative bias. The charge-flux relation portrayed the non-ideal or memristive nature of the devices. The reliability in the RS process was analyzed in detail using Weibull distribution and time series analysis techniques. The device exhibits stable and multilevel endurance and retention characteristics which demonstrates the suitability of the device for the high-density non-volatile memory application. The current conduction of the device was dominated by Ohmic and trap controlled-space charge limited current (TC-SCLC) mechanisms and filamentary RS process responsible for the BRS in the device. In a nutshell, the present investigations reveal the potential use of the iron tungstate for the fabrication of memristive devices for the non-volatile memory application.

Stable and repeatable ZrO2 RRAM achieved by NiO barrier layer for negative set phenomenon elimination

Resistive random-access memory (RRAM) is a promising non-volatile memory technology due to its fast operation, low power consumption, and high reliability. However, the negative set phenomenon remains a challenge for RRAM, which can lead to the deterioration of device switching parameters. In this study, we successfully addressed this issue by inserting a NiO blocking layer between the ZrO2 and Ag top electrodes in ZrO2-based RRAM. In addition, the resistive switching characteristics of the device are significantly enhanced by the incorporation of a p-type oxide NiO layer. Compared to single-layer ZrO2 devices, the double-layer Ag/NiO/ZrO2/ITO RRAM exhibits improved cycling durability (>500 cycles) and good retention time (3 × 104s). Our analysis of the device conduction mechanism and proposed resistive switching model suggest that oxygen vacancies play a connecting role in the reset process, leading to failed reset behavior. Through the incorporation of a p-type semiconductor NiO layer into ZrO2-based RRAMs, the interference of oxygen vacancies on the reset process can be effectively impeded. This approach not only provides an effective resolution to the unforeseen negative set phenomenon in RRAM devices, but it also holds paramount significance for the advancement of high-performance RRAMs.

Design of high-performance entangling logic in silicon quantum dot systems with Bayesian optimization

Device engineering based on computer-aided simulations is essential to make silicon (Si) quantum bits (qubits) be competitive to commercial platforms based on superconductors and trapped ions. Combining device simulations with the Bayesian optimization (BO), here we propose a systematic design approach that is quite useful to procure fast and precise entangling operations of qubits encoded to electron spins in electrode-driven Si quantum dot (QD) systems. For a target problem of the controlled-X (CNOT) logic operation, we employ BO with the Gaussian process regression to evolve design factors of a Si double QD system to the ones that are optimal in terms of speed and fidelity of a CNOT logic driven by a single microwave pulse. The design framework not only clearly contributes to cost-efficient securing of solutions that enhance performance of the target quantum operation, but can be extended to implement more complicated logics with Si QD structures in experimentally unprecedented ways.

Energy‐efficient switching method using input‐swapping for high‐resolution successive approximation register analog‐to‐digital converters

AbstractThis paper presents an energy‐efficient digital‐to‐analog converter (DAC) switching method with low common‐mode variations for high‐resolution successive approximation register (SAR) analog‐to‐digital converters (ADCs), while enabling to implement resolutions such as 14‐bit as compared to the typical 10‐bit. The proposed switching method enables high resolution by having a nearly constant common‐mode voltage and employing input‐swapping to use the reference voltage (Vref) only in the sampling phase. This method eliminates the need for the third reference voltage during the entire DAC switching steps, which reduces the required number of switches at the bottom plates of the capacitors. The use of lower number of switches not only lowers the DAC control logic complexity, but also results in a faster operation, lower power, and smaller area. When compared to conventional 10‐bit SAR ADCs, the proposed switching method in a 10‐bit implementation reduces the average energy and area by 96.09% and 75%, respectively, while offering high‐resolution implementation options such as 14 bits.

A novel viscoelastic microfluidic platform for nanoparticle/small extracellular vesicle separation through viscosity gradient-induced migration.

Small extracellular vesicles (sEVs) are extracellular vesicles with diameters ranging from 30 to 150 nm, harboring proteins and nucleic acids that reflect their source cells and act as vital mediators of intercellular communication. The comprehensive analysis of sEVs is hindered by the complex composition of biofluids that contain various extracellular vesicles. Conventional separation methods, such as ultracentrifugation and immunoaffinity capture, face routine challenges in operation complexity, cost, and compromised recovery rates. Microfluidic technologies, particularly viscoelastic microfluidics, offer a promising alternative for sEV separation due to its field-free nature, fast and simple operation procedure, and minimal sample consumption. In this context, we here introduce an innovative viscoelastic approach designed to exploit the viscosity gradient-induced force with size-dependent characteristics, thereby enabling the efficient separation of nano-sized particles and sEVs from larger impurities. We first seek to illustrate the underlying mechanism of the viscosity gradient-induced force, followed by experimental validation with fluorescent nanoparticles demonstrating separation results consistent with qualitative analysis. We believe that this work is the first to report such viscosity gradient-induced phenomenon in the microfluidic context. The presented approach achieves ∼80% for both target purity and recovery rate. We further demonstrate effective sEV separation using our device to showcase its efficacy in the real biological context, highlighting its potential as a versatile, label-free platform for sEV analysis in both fundamental biological research and clinical applications.

High performance antimony-rich RexSb3Te for phase-change random access memory applications

Phase-change random access memory (PCRAM) demands for high-performance phase change materials, including operation speed, data retention, resistance drift etc. In this work, a high performance PCRAM device based on antimony-rich RexSb3Te material was put forward and studied. Excellent data retention, fast operation speed, low resistance drift, low power consumption and good cycle characteristics were achieved. The lattice information, bonding properties and surface morphology of the films were characterized by transmission electron microscopy, Raman spectroscopy and atomic force microscopy. Density functional theory calculations show that the Re dopant is more inclined to replace Sb and forms chemical bonds with Te, and the Re-Te bonds are more stable than the previous Sb-Te bonds, which is conducive to the formation of stable precursors to accelerate nucleation. The research shows that the antimony-rich Re0.18Sb3Te material has good overall performance, which provides a strategy for developing high-performance memory.

Gate-Tunable Multiband van der Waals Photodetector and Polarization Sensor.

A single photodetector with tunable detection wavelengths and polarization sensitivity can potentially be harnessed for diverse optical applications ranging from imaging and sensing to telecommunications. Such a device will require the combination of multiple material systems with different structures, band gaps, and photoelectrical responses, which is extremely difficult to engineer using traditional epitaxial films. Here, we develop a multifunctional and high-performance photosensor using all van der Waals materials. The device features a gate-tunable spectral response that is switchable between near-infrared/visible and short-/midwave infrared, as well as broad-band operation, at room temperature. The linear polarization sensitivity in the telecommunication O-band can also be directly modulated between horizontal, vertical, and nonpolarizing modes. These effects originate from the balance of photocurrent generation in two of the active layers that can be manipulated by an electric field. The photodetector features high detectivity (>109 cmHz1/2W-1) together with fast operation speed (∼1 MHz) and can be further exploited for dual visible and infrared imaging.

High data rate and energy efficient configurable IR-UWB transmitter with an integrated balun

This paper presents a novel, digitally configurable, switching oscillator-based impulse radio ultra-wideband (IR-UWB) transmitter that is robust to process variations. The pulse width and pulse position properties of the output waveform are configurable to ensure operation for the desired bandwidth and output pulse energy values. The architecture is based on a cross-coupled LC voltage-controlled oscillator (LC VCO) implemented with a custom-designed on-chip balun at a center frequency of 2.4 GHz. With the usage of this on-chip balun, the need for an extra buffer stage is eliminated, and the highest possible efficiency is achieved with the proper turns ratio selected. The generated digital control pulse signals are also used to ensure fast start-up and UWB operation while maintaining low power consumption with an implemented on/off tail switching scheme. The presented IR-UWB transmitter that occupies a total area of 0.35 mm2 is fabricated in the United Microelectronics Corporation (UMC) 180-nm mixed-mode/radio frequency (RF) CMOS process. The measured output voltage swing of the fabricated transmitter is 0.812 V on a 50-Ω load for the 200 Mb/s data rate, and the bandwidth is measured as 902 MHz. The achieved frequency tuning range is 1 GHz and the fabricated transmitter can drive 50 Ω, 75 Ω and 100 Ω loads with measured efficiency values 4.16%, 5.76%, and 4.05%, respectively. Compared to other works in the literature, this design achieves a higher output pulse energy at a higher data rate while maintaining low power consumption and, thus, high efficiency.

Engineering Spin-Orbit Interactions in Silicon Qubits at the Atomic-Scale.

Spin-orbit interactions arise whenever the bulk inversion symmetry and/or structural inversion symmetry of a crystal is broken providing a bridge between a qubit's spin and orbital degree of freedom. While strong interactions can facilitate fast qubit operations by all-electrical control, they also provide a mechanism to couple charge noise thereby limiting qubit lifetimes. Previously believed to be negligible in bulk silicon, recent silicon nano-electronic devices have shown larger than bulk spin-orbit coupling strengths from Dresselhaus and Rashba couplings. Here, it is shown that with precision placement of phosphorus atoms in silicon along the [110] direction (without inversion symmetry) or [111] direction (with inversion symmetry), a wide range of Dresselhaus and Rashba coupling strength can be achieved from zero to 1113 × 10-13eV-cm. It is shown that with precision placement of phosphorus atoms, the local symmetry (C2v, D2d, and D3d) can be changed to engineer spin-orbit interactions. Since spin-orbit interactions affect both qubit operation and lifetimes, understanding their impact is essential for quantum processordesign.

Smart Home Automation System

In fast moving world, where people are very busy in their own things, there is a need for automation in all activities, not only industries and machineries; even home automation is of prime importance. As of now, for automation purposes we use different wireless technologies and that process uses a PC, voice processor etc., these have their own limitations and results in decreased accuracy. In order to provide more reliable and convenient automation we use android applications. Smart phones are becoming more popular now a days and each of us are having a smart phone in present situation. So by using dedicated applications on an android device complete automation can be done and this to a great level will decrease the drawbacks caused by other conventional wireless technological processes. It has a variety of advantages over conventional old microcontrollers such as RISC architecture, larger memory word, fast operation and a host of inbuilt features such as ADC, communication protocols etc., The project can be used to control any external environment where in the person may like to control all his surroundings such as fans, lights, TVs, etc; He may also like to open the door for someone or close the water tap.

Components of Wireless Charging Technology for Smart Cars and Simple Applications

A wireless charging smart car that can perform rapid short-term wireless charging was designed in this research. This car features energy-saving, fast, and efficient operation, with strong usability and potential for development. The CH32V307VCT6 microcontroller is used as the main controller for the smart car, and the CH32V203C8T6 microcontroller functions as a control chip for the wireless charging transmitting end. Combining the use of a super-capacitor group as an energy storage device along with the DRV8701 motor drive and corresponding sensors, it enables the smart car to accomplish wireless charging and automatic tracking. The wireless transmission terminal of this project employs an LCC compensation circuit method and an inverter circuit to achieve high-power wireless charging of 600W. The wireless charging receiver module receives and converts electrical energy to ultimately power the movement of the smart car.

Fast-speed and low-power-consumption optical phased array based on lithium niobate waveguides

Abstract Fast scanning speed and low-power consumption are becoming progressively more and more important in realizing high-performance chiplet optical phased arrays (OPAs). Here, we successfully demonstrated integrated OPAs with multiple waveguides channels based on thin-film lithium niobate-on-insulator (LNOI) platform. Specifically, two lithium niobate (LN) OPA chips have been implemented with 32 and 48 channels LN waveguides, respectively, enabled by electro-optic modulations, which showcases the low power consumption (1.11 nJ/π) and fast operation speed (14.4 ns), showing obvious advantage of the LNOI platform over others. As results, we experimentally achieved a beam steering with a 62.2° × 8.8° field of view (FOV) and a beam divergence of 2.4° × 1.2° for 32 channels, and a FOV of 40° × 8.8° and a beam divergence of 0.33° × 1.8° for 48 channels. This work also demonstrates the feasibility of LNOI platform in scalable OPA chips.

Ferroelectric tunnel junctions: promise, achievements and challenges

Abstract Ferroelectric tunnel junctions (FTJs) have been the subject of ongoing research interest due to its fast operation based on the spontaneous polarization direction of ultrathin ferroelectrics and its simple two-terminal structure. Due to the advantages of FTJs, such as non-destructive readout, fast operation speed, low energy consumption, and high-density integration, they have recently been considered a promising candidate for non-volatile next-generation memory. These characteristics are essential to meet the increasing demand for high-performance memory in modern computing systems. In this review, we explore the basic principles and structures of FTJs and clarify the elements necessary for the successful fabrication and operation of FTJs. Then, we focus on the recent progress in perovskite oxide, fluorite, 2-dimensional van der Waals, and polymer-based FTJs and discuss ferroelectric materials expected to be available for FTJs use in the future. We highlight various functional device applications, including non-volatile memories, crossbar arrays, and synapses, utilizing the advantageous properties of ferroelectrics. Lastly, we address the challenges that FTJ devices currently face and propose a direction for moving forward.

Polarizability Engineering of Surface Flattening Molecular Dipoles for Fast and Long Lithium Metal Battery Operation

To overcome the energy limitations of conventional Li‐ion batteries (LIB), renewed attention has been given to Li‐metal anodes, which provide the highest capacity and lowest anode potential. To realize Li‐metal batteries (LMBs), it is crucial to stabilize unwanted side reactions on the surface and to inhibit problematic dendrite growth, which causes short‐circuit issues. Herein, diverse pyrrolidone‐based molecular dipole additives controlled by different functional groups are introduced as trifunctional surface stabilizers. It is discovered that the Li–Li symmetric cell improves proportionally with the molar volume and corresponding polarizability values of the molecular dipoles. The highly polarizable pyrrolidone‐based molecular dipoles offer exceptional benefits, including surface flattening of the Li metal anode, controlling the growth direction of crystalline Li, and forming durable solid electrolyte interface (SEI) components. The study is based on polarizability‐controlled molecular dipoles, and offers an effective approach for designing advanced surface stabilizers to develop of high‐performance LMBs.

Hydrogen-Driven Low-Temperature Topotactic Transition in Nanocomb Cobaltite for Ultralow Power Ionic-Magnetic Coupled Applications.

We reversibly control ferromagnetic-antiferromagnetic ordering in an insulating ground state by annealing tensile-strained LaCoO3 films in hydrogen. This ionic-magnetic coupling occurs due to the hydrogen-driven topotactic transition between perovskite LaCoO3 and brownmillerite La2Co2O5 at a lower temperature (125-200 °C) and within a shorter time (3-10 min) than the oxygen-driven effect (500 °C, tens of hours). The X-ray and optical spectroscopic analyses reveal that the transition results from hydrogen-driven filling of correlated electrons in the Co 3d-orbitals, which successively releases oxygen by destabilizing the CoO6 octahedra into CoO4 tetrahedra. The transition is accelerated by surface exchange, diffusion of hydrogen in and oxygen out through atomically ordered oxygen vacancy "nanocomb" stripes in the tensile-strained LaCoO3 films. Our ionic-magnetic coupling with fast operation, good reproducibility, and long-term stability is a proof-of-principle demonstration of high-performance ultralow power magnetic switching devices for sensors, energy, and artificial intelligence applications, which are keys for attaining carbon neutrality.

A pilot protection based on low frequency component model for HVDC transmission lines

AbstractReliable and fast identification of high‐voltage direct current (HVDC) transmission line faults is important to the safety of power system. In traditional DC transmission line protection, differential protection is invulnerable to high fault resistance, but it needs long time delay for the influence of distributed capacitance current. In order to solve this problem, a novel pilot protection is proposed. The characteristics of the voltage and current processed by low‐pass filter under different fault conditions are analysed, and based on it the protection criteria is proposed. When external fault occurs, it reflects the line capacitance where the first forward fault traveling wave passes, which is increasing until equal to the whole line capacitance, then remains constant. However, when internal fault occurs, its value is negative in the initial stage, and after that its value is very different from the whole line capacitance. The analysis proves that this pilot protection method has fast operation speed, and can be applied for a relatively long period of time. What is more, the applicable time of superposition principle is considered in the analysis, which is not considered in many literatures. An UHVDC system is modelled for simulation in PSCAD/EMTDC, and the correctness and effectiveness of the proposed scheme is verified.

Electric Vehicle Aggregation in a PV-Battery Charging Station: A Contract-Based Approach

As the proportion of high-power fast charging piles increases, how to more stably aggregate electric vehicles to avoid market risks brought about by user charging behavior is an urgent problem for charging station operators. This is especially so for fast charging station operators. To address this issue, a retail package design method for PV-battery charging stations based on contract theory and Lyapunov optimization is proposed in this paper. The operator can formulate optimal charging and discharging packages under asymmetric information in the day-ahead and real-time stages. Packages with fixed power and prices will be offered to users to reduce the impact of user behavior uncertainty. In addition, the queuing problems of pile allocation and PV-battery energy management are resolved by the Lyapunov drift optimization method. The performance indicators, such as the average power and demand processing capability of in-station equipment, will be optimized while ensuring the stability of the queuing network. The simulation verifies that the proposed method can improve the operator's net income and make the social welfare approach the theoretical value under complete information. Moreover, it shows stronger stability in terms of user aggregation.

Microwave Vertebrae Strength Probe Development: Robust and Fast Phase Unwrapping Technique.

We have developed a new transmission-based, open-ended coaxial probe for assessing vertebrae strength during spinal fusion surgery. The approach exploits the fact that the probes are within the far field of each other implying that the phase varies linearly with respect to propagation distance. Determining the absolute phase is critical for recovering the associated tissue dielectric properties from which bone strength will be determined. Unfortunately, unwanted multi-path signals corrupt the signals at the lower end of the operating frequency range from which our conventional unwrapping strategy depends. Our new approach requires only three measurements within the prime frequency range and can be determined robustly with a minimum of computations. This will be vital to developing a commercial device since the signal levels will be extremely low power requiring longer than usual data acquisition times, which will be mitigated by measuring the data at only a few frequencies. Fast and efficient operation will be critical for clinical success.