Hasil untuk "Electric apparatus and materials. Electric circuits. Electric networks"

Yi‐Cheng Lo, Liao‐Jia Wang, Yu‐Chang Chen

ABSTRACT We systematically investigate the electronic structures of pristine monolayer WSe2 and WSe2 superlattices with periodic nitrogen substitution. Unlike random doping, which often introduces in‐gap impurity states, periodic nitrogen doping primarily modulates the bandgap, thereby facilitating effective bandgap engineering for electronic and optoelectronic applications. The gap narrows monotonically with increasing dopant density (pristine > 8‐row > 6‐row > 4‐row), directly influencing device switching. We also evaluate the FET performance of nanojunctions created by these configurations by examining the contour plot of current density as a function of temperature and gate voltage, which quantifies how bandgap engineering affects switching characteristics. Our calculations clarify the classical‐quantum crossover in sub‐10 nm 2D FETs: as T rises, J approaches the thermionic current; as T falls, quantum tunneling dominates, and the steep energy dependence of τ(E) may break the classical limit of subthreshold swing imposed by the Boltzmann tyranny. The optimal gating range (VgON, VgOFF) is investigated for each temperature, insensitive to temperature in the high‐temperature regime, confirming the good thermal stability of the FET devices. A comparison study demonstrates that the 4‐row structure, with excessively large JOFF, severely low ON/OFF ratio, and restricted operation range, is inappropriate for realistic FET applications. The pristine structure has the highest performance across all measures, but its high VgOFF (∼1.1 V) makes it less practical, since such a large threshold voltage may promote time‐dependent dielectric breakdown (TDDB) of the oxide layer, reducing device dependability. The 6‐row and 8‐row structures are slightly inferior to the pristine in terms of performance, but exhibit more favorable VgOFF values (∼0.75 V), achieving a balance between reasonable threshold voltage and stable operation range, making them more promising candidates for future FET integration.

Sitong Mu, Mahmoud Wagih

The Internet of Things (IoT) increases the demand for battery-less devices, driving the development of Radio Frequency (RF) energy harvesting and wireless power transfer (WPT) technologies, with RF identification (RFID) being an exemplar of mass-manufacturable RF-powered devices. RF-DC rectifiers are the core enabler, and also bottleneck, for sensitive, long-range wireless-powered systems. Unlike discrete-component rectifiers, fully-integrated RFIC and MMIC rectifiers offer advantages in form factor, scalability, and system-on-chip (SoC) co-integration capabilities. Through SoC integration, WPT can be adopted more broadly in applications such as biomedical implants, wearable sensors, and IoT nodes. This comprehensive review covers CMOS-based integrated rectifier designs, with a roadmap to SoC and system integration from dies, packages, to systems. Rectifier topologies are categorized into three major groups: voltage doublers, cross-coupled rectifiers, and reversed amplifier-inspired architectures, with the self-compensation techniques further discussed as possible performance enhancement strategies. A dataset of over 120 published rectifiers is analyzed to extract performance trends over frequency, process node, power sensitivity, efficiency, and circuit integration approaches. In addition, practical applications in both IoT systems and RFID-based platforms are examined to demonstrate the functional advantages of integration. The review highlights the evolution of rectifier performance metrics over time and provides insights into trade-offs among efficiency, sensitivity, and power dynamic range. As energy-autonomous electronics continue to expand across domains, integrated rectifiers are expected to remain a foundational building block in future low-power, wireless-powered systems.

Lina Koschinski, Thomas Grap, Erkan Yilmaz et al.

Abstract The development of high‐density microelectrode arrays (MEAs) for large‐scale brain recordings requires neural probes with reduced footprints to minimize tissue damage. One way to achieve this is by implementing dense electrode arrays with narrower feedline dimensions, though this increases susceptibility to capacitive coupling between electrical interconnects. To address this, this study explores the resolution limits for high‐density flexible MEAs by optimizing the fabrication using optical contact lithography (OCL) and electron beam lithography (EBL). OCL enables metal feedlines with widths of 520 nm and interconnect spaces of 280 nm, while EBL allows the realization of 50 nm feedlines with 150 nm spaces on flexible parylene C substrates. Based on these techniques, we fabricate a flexible 64‐channel intracortical implant with a miniaturized cross‐section of only 50 × 6 or 70 × 6 µm2. In vivo validation in awake rats demonstrates that the fabricated, high‐density flexible intracortical implants with submicron feedline resolution offer low‐impedance electrodes and reduced crosstalk, enabling reliable neuronal recordings. These findings demonstrate the feasibility of miniaturizing flexible MEAs using a single‐metal layer process, thereby reducing manufacturing complexity in high‐density thin‐film polymer‐based neural interfaces.

Tao Yue, Yuyin Zhang, Yuanjie Gan et al.

Abstract Tactile information, serving as the most intricate form of data humans gather from the external environment, has long been a significant area of focus for wearable flexible sensors. The advancement of wearable technology and robotics in healthcare has spurred research into integrating thin, compact flexible sensors into robotic systems for mimicking human tactile tissue manipulation during surgery and data collection. Here, a continuous injection method is used to fabricate a multi‐layer liquid metal sensor. By laminating multiple PDMS microfluidic layers, the two parameters of pressure and deformation are simultaneously measured in a decoupled manner. The compact and thin design of the sensor facilitates its integration into fingers or robotic digits, enabling assistance by deforming upon contact with materials and identifying their hardness through applied pressure. Separate performance tests of the two sensors show that the strain and pressure functions are decoupled from each other, and their ratios can identify and classify the hardness of different contact materials (glass, PDMS, and silicone). The hardness sensor can assist robots in operating human tissues during medical surgeries. The demonstrated fabrication and integration approaches provide a path toward tactile sensor applications in medical treatment, rehabilitation, services, and other processes.

Keishi Sunami, Sachio Horiuchi, Shoji Ishibashi et al.

Abstract The convergence of electronics and photonics is attracting attention for its potential to surpass performance limitations of existing information‐processing devices. In particular, the electro‐optic (EO) effect plays a critical role in high‐speed and low‐power conversion between electrical and optical signals, which is demanded for future communication networks. Here, a novel class of EO material is demonstrated, the organic ferroelectric crystal of croconic acid (CRCA). The recently developed birefringence field‐modulation imaging technique enables high‐throughput evaluation of the EO coefficient for as‐grown bulk crystals, unveiling a figure of merit of >400 for CRCA, which exceeds that of 320 in the conventional EO material LiNbO3 in the visible‐light range. Analyses in conjunction with theoretical calculations clarify that its remarkable EO performance is attributable to deformation of the π‐orbital coupled with the proton displacement. This finding provides a new route for the molecular design of high‐performance EO materials: proton–π‐electron‐coupled ferroelectrics.

Saransh Shrivastava, Wei‐Sin Dai, Stephen Ekaputra Limantoro et al.

Abstract Due to the imitation of the neural functionalities of the human brain via optical modulation of resistance states, photoelectric resistive random access memory (ReRAM) devices attract extensive attraction for synaptic electronics and in‐memory computing applications. In this work, a photoelectric synaptic ReRAM (PSR) of the structure of ITO/Zn2SnO4/Ga2O3/ITO/glass with a simple fabrication process is reported to imitate brain plasticity. Electrically induced long‐term potentiation/depression (LTP/D) behavior indicates the fulfillment of the fundamental requirement of artificial neuron devices. Classification of three‐channeled images corrupted with different levels (0.15–0.9) of Gaussian noise is achieved by simulating a convolutional neural network (CNN). The violet light (405 nm) illumination generates excitatory post synaptic current (EPSC), which is influenced by the persistent photoconductivity (PPC) effect after discontinuing the optical excitation. As an artificial neuron device, PSR is able to imitate some basic neural functions such as multi‐levels of photoelectric memory with linearly increasing trend, and learning‐forgetting‐relearning behavior. The same device also shows the emulation of visual persistency of optic nerve and skin‐damage warning. This device executes high‐pass filtering function and demonstrates its potential in the image‐sharpening process. These findings provide an avenue to develop oxide semiconductor‐based multifunctional synaptic devices for advanced in‐memory photoelectric systems.

Himanshu Mavani, Kai Huang, Kartik Samanta et al.

Spin-split antiferromagnets have significance for antiferromagnetic (AFM) spintronics due to their momentum dependent spin polarization which can be exploited for the control and detection of the AFM order parameter. Here, we explore the polar-layer stacking of AFM-ordered bilayers driving the emergence of reversable electric polarization and non-relativistic spin splitting (NRSS) of their band structure. Based on the spin-space group approach, we identify several representative two-dimensional AFM materials which exhibit different types of NRSS when stacked into a polar bilayer. We demonstrate that NRSS can have both altermagnetic and non-altermagnetic origins and elucidate symmetry requirements for NRSS to be switchable by electric polarization. We argue that the electric polarization switching of NRSS in polar AFM bilayers may be more practical for device applications than the current-induced Néel vector switching.

J. Amira Geuther, Marit R. Fiechter, Jeremy O. Richardson

Strong electric fields can be used to align molecules. However, a non-polar molecule such as H$_2$ has no preference for its orientation. There are thus two equivalent configurations with equal energy separated by a potential-energy barrier. Quantum mechanically, the molecule can tunnel between these configurations resulting in a tunnelling splitting, which in the case of H$_2$, is the same as the ortho--para splitting. In this work, we generalize semiclassical instanton theory to calculate the energy splitting of molecules in electric fields in full dimensionality. This goes beyond a perturbative treatment of the field and takes into account changes in molecular geometry during the tunnelling process which influence its electrical properties and can have a significant impact on the result. We first study the case of H$_2$ in a static electric field and then show how it can be applied to larger polar molecules subjected to oscillating electric fields, where we find that even large-amplitude heavy-atom tunnelling can lead to observable splittings.

Zdzislaw Trzaska

Jie Wu, Jian Guo, Yifeng Ren et al.

Abstract To meet the needs of energy storage under high temperature and high pressure, a high‐entropy relaxor ferroelectric ceramic, La‐modified (Bi0.2Na0.2Ba0.2Sr0.2Ca0.2)TiO3 is prepared, which has excellent thermal and mechanical stability. At the wide temperature range of 327–689 K (tan δ < 0.01) and below ≈7 GPa, the material shows extraordinary functional performance. Comprehensive study indicates that the ceramic possesses a single‐phase cubic perovskite structure, and as the pressure increases, the material undergoes a transition at ≈8 GPa, in which enormous large grains crack into smaller grains, but the space group Pm3¯m does not change. In addition, with further compression, the grains begin to rotate and re‐orientate at ≈9 GPa. Based on the investigations, it is considered that the suitable doping of multiple cations can effectively improve the stability of ceramics, and it also paves the experimental way to further study thermally and mechanically stable high‐entropy ceramics.

Peter H. Siegel

Welcome to Volume 4 of <sc>IEEE Journal of Microwaves</sc>&#x0021; In this issue, we bring you 11 quality papers: two invited and nine regular submissions. We also celebrate six of our Outstanding Reviewers of 2023 and announce our <sc>IEEE Journal of Microwaves</sc> 2022 Best Paper prize. Our author and reader pools continue to expand and our usage counts per article published now exceed 1530. All of our 232 published articles from 2021 to 2023 now appear on Clarivate&#x0027;s Web of Science and we are looking forward to possibly receiving an impact factor this July. Remember to take a look at our solicitation for papers that can fit into our <italic>Microwaves in Climate Change</italic> special issue, which we intend to release before the end of 2024.

Andrey Rybakov, Adolfo O. Fumega, Dorye L. Esteras et al.

Layered van der Waals two-dimensional (2D) magnets are a cornerstone of ultrathin spintronic and magnonic devices. The recent discovery of a 2D multiferroic with strong magnetoelectric coupling in NiI$_2$ offers a promising platform for the electrical control of spin-wave transport. In this work, using ab initio calculations, we investigate how the magnonic properties of monolayer NiI$_2$ can be controlled using an external electric field. We show that the emergence of a ferroelectric polarization leads to an energy splitting in the magnon spectrum, thus establishing a way to detect the electric polarization experimentally. We also show the modulation of the magnon splitting and the energy position of the singularities in magnon DOS by an electric field due to the strong magnetoelectric coupling. Our results highlight the interplay between ferroelectricity and magnons in van der Waals multiferroics and pave the way to design electrically tunable magnetic devices at the 2D limit.

Munyaradzi J. Chihota, Courtney Devine, Bernard Bekker

V. Anitha, Orlando Juan Marquez Caro, R. Sudharsan et al.

The aim of this paper is to create a decentralized transparent voting and analysis system that can be implemented with blockchain to provide an efficient and highly secure justifiable method of election systems in countries where traditional physical voting with gameable securities is used, increasing the chances of rigged elections. This system is designed to focus on a secure voting system, lower costs, faster wait times, no disparities due to various erroneous proxies, high scalability, and geographic independence. Overall, an effective election mechanism to strengthen the democratic process. The proposed dApp allows voters to vote from the comfort of their own homes, saving time and reducing the number of false votes registered.

Petr S. Bednyakov, Jiří Hlinka

Abstract Previous experiments with barium titanate crystals have shown that electric field applied in the vicinity of its ferroelectric phase transition can be used to introduce peculiar ferroelectric domain walls, persisting to the ambient conditions: head‐to‐head charged walls compensated by the 2D electron gas. The present in situ optical observations allow the documentation of the early stage of this poling process in which the cubic and ferroelectric phases coexist, the latter being broken into multiple martensitic superdomains, separated by superdomain boundaries. It is revealed that the transient superdomains are subsequently converted into the regular ferroelectric domains, while the superdomain boundaries transform into the desired charged domain walls. In order to assign the observed transient domain patterns, to understand the shapes of the observed ferrolectric precipitates and their agglomerates as well as to provide the overall interpretation of the recorded domain formation process, the implications of the mechanical compatibility of the coexisting superdomain states are derived in the framework of the Wechsler–Lieberman–Read theory. These results also suggest that both the electric conductivity and interlinked motion of the superdomain boundaries and phase fronts are involved in the transport of the compensating charge carriers toward the charged domain wall location.

Yannick Raffel, Franz Müller, Sunanda Thunder et al.

In this invited article we present a comprehensive overview of 28 nm high-k-metal gate-based ferroelectric field effect transistor devices for synaptic applications. The devices under test were fabricated on 300 mm wafers at GlobalFoundries. The fabricated devices demonstrate 103WRITE-endurance cycles and 104seconds of data-retention capability at 85 °C. We have also assessed the FeFET-based crossbar array’s performance in system-level applications. The system performance was assessed by simulating the FeFET crossbar array for neuromorphic applications. For datasets from the National Institute of Standards and Technology (MNIST), the crossbar array achieved software-comparable inference accuracy of about 97% using multilayer perceptron (MLP) neural networks.

John Barr

This paper will present a historical overview of the IEEE Microwave Theory and Technology Society (MTT-S) from its inception in 1952 to the present times. As there is a vast amount of activities to cover, this paper will just provide a high-level summary of some of the more notable activities and trends. The paper will be organized on a decade-by-decade basis. In each decade, there will be coverage of the major activities of MTT-S by following the actions of the Administrative Committee, the conferences and symposiums, the publications, and the growth of the membership and chapter activities. Additionally, there will be brief discussions on the key relationships that MTT-S had with other professional groups inside and outside of the IEEE and of the key technologies that the MTT-S community was involved with at the time. For brevity, individual names will generally be left out but pointers to internet listings of major contributors will be provided.

Tianyi Gao, Leyan Nian, Li Jin et al.

Abstract High tunability of photoconductivity is highly desired for applications in optical memories, sensors, and bioelectronics. Recently, room temperature persistent photoconductivity (PPC) in SrTiO3 (STO) has been revealed and has attracted great attention. However, reversible switching of the PPC in STO with a large on/off ratio remains challenging to date. Here, a giant switchable PPC in soft chemistry reduced STO is reported. An initial insulator‐to‐metal transition with on/off ratio up to 7 orders of magnitude is observed and about 5 orders of magnitude transition is found to be reversible. Via nuclear magnetic resonance measurements, it is uncovered that such unusual PPC is driven by the generation of excess carriers accompanied with a configuration evolution of the incorporated hydrogen from hydridic HO+ to protic Hi+ upon illumination. The work demonstrates giant switchable PPC transition in soft chemistry reduced perovskite oxides, providing a new platform for pursuing high performance sensors and nonvolatile optoelectronic memory devices.

Radha Priyadharsini G, Krishnaveni K

The use of facial emotion recognition (FER) technologies will become more pervasive in our everyday lives. Emotional awareness is advantageous for many types of businesses and areas of life. It is advantageous and important for reasons of security and heath. Deep hierarchical FER systems often focus on the following two main problems; going out of control due to identification factors including lighting, face location, and recognition bias, as well as a lack of training data. We developed each Deep Convolutional Neural Network (DCNN) based on a Binary Attention Mechanism (BAM) for the facial emotion recognition issue in our proposed system. Each image of a face has to be assigned to one of the seven facial emotions. An updated BAM-DCNN model was trained using the original pixel data characteristics. The Histogram of Oriented Gradients (HOG) is used for data preparation. To lessen the overfitting of the models, we used dropout and batch normalization in addition to L2 regularization. The recommended technique enables the detection of human emotion in images by automatically recognizing, extracting, and evaluating diverse face expressions. We extract and examine performance assessment measures from FER datasets, including recognition accuracy, precision, sensitivity, specificity, recall, and F1 score. To demonstrate the effectiveness of our system, we also contrast the recommended technique with the practices now in use.

Sara Heshmatian, Fatemeh Ahmadi, Alexander Trounev

In this article, we investigate the thermal equilibration of the holographic QCD model dual to the Einstein-Maxwell-Dilaton (EMD) gravity in the presence of an external electric field. The model captures the QCD features at finite temperature and finite chemical potential in both confinement and deconfinement phases and could be considered a good candidate to study the dynamics of the strongly interacting system in out-of-equilibrium conditions. For this purpose, we examine the instability imposed by an external electric field using the AdS/CFT dictionary and study the electric current flow and its relaxation for this holographic model. We study the effects of temperature, electric field strength, and chemical potential on the current flow of the stationary state by applying a constant electric field. Additionally, for a time-dependent electric field, we investigate the relaxation time scales of the system using equilibration time. Finally, we compare our results with those from other holographic models and experiments.