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

Chuang Zhang, Hanzhao Song, Chee Keong Tan

ABSTRACT β‐Ga2O3, with its ultrawide bandgap (∼4.9 eV) and well‐established n‐type conductivity, is a promising semiconductor for next‐generation power electronics. However, the realization of stable p‐type doping remains a fundamental challenge owing to the deep‐acceptor levels of conventional dopants. Here, a Te–Mg co‐doping strategy is developed via metal–organic chemical vapor deposition (MOCVD) to overcome this limitation. The co‐doped films exhibit a room‐temperature resistivity of 32.4 Ω·cm, a Hall hole concentration of 1.78 × 1017 cm−3, and mobilities up to 5.29 cm2 V−1 s−1 at lower carrier concentrations (5.72 × 1014 cm−3). A preliminary p–n diode is successfully demonstrated. Density functional theory (DFT) calculations reveal that Te incorporation introduces an intermediate band near the valence band maximum (VBM), effectively reducing the Mg acceptor ionization energy. Spectroscopic analyses further confirm VBM elevation through Te–Ga orbital hybridization and a Fermi‐level shift toward the valence band, consistent with p‐type behavior. These results establish a viable route for achieving p‐type β‐Ga2O3 homoepitaxy and lay the groundwork for future optimization toward sub‐1 Ω·cm resistivity and a deeper understanding of the Te–Mg doping mechanism, paving the way for bipolar device applications in ultrawide‐bandgap electronics.

Gyanendra Kumar, Sur Singh Rawat, Jyoti Gautam et al.

Unmanned aerial vehicles (UAVs) have become indispensable in both civilian and military domains, enabling applications such as smart surveillance, environmental monitoring, and search-and-rescue operations. However, effective object detection in UAV imagery remains challenging due to the small size of targets, high object density, frequent occlusions, and complex backgrounds resulting from varying altitudes and viewpoints. Existing algorithms, such as You Only Look Once (YOLO) v5, exhibit limited accuracy in detecting targets in UAV images. To address these challenges, this study proposes an enhanced YOLOv5-based detection model. The model incorporates an optimized detection module with three prediction heads for multi-scale bounding box predictions. Additionally, self-attention mechanisms and a Convolutional Block Attention Module (CBAM) are integrated to focus on salient regions and mitigate the impact of occlusions. Furthermore, we introduce a ConvELU layer, which replaces the default SiLU activation with the Exponential Linear Unit (ELU). This modified ConvELU layer is applied to the backbone, neck, and head components, effectively improving the model's feature extraction capabilities. Experimental results of the VisDrone dataset demonstrate that the proposed model achieves a precision of 95.1 %, a recall of 86.3 %, and a mean Average Precision (mAP) of 91.6 %, outperforming the standard YOLOv5 and other state-of-the-art detectors.

Abhishek Kumar, Charles H. Devillers, Rita Meunier‐Prest et al.

Abstract Interface engineering in organic heterostructures is an important approach to tuning the characteristics of organic electronic devices and improving their performances in applications, such as gas sensing. Herein, organic heterostructures containing, a polyporphine (pZnP‐1), perfluorinated copper phthalocyanine (Cu(F16Pc)), and lutetium bis‐phthalocyanine (LuPc2) are synthesized by a combination of electrochemical and PVD methods for investigation of charge transport and ammonia (NH3)  sensing application. pZnP‐1 is synthesized by controlled oxidative electropolymerization and reveals a rough surface, which influences the electrical nature of its interface with the phthalocyanine. The electrical properties of the heterojunction devices reveal distinct interfacial and bulk charge transport properties, which are modulated by the thickness of pZnP‐1 and the external electric field. Indeed, the heterojunction device containing a thin film of pZnP‐1 displays n‐type behavior at low bias and p‐type nature at higher bias; i.e., an ambipolar behavior, in which ambipolarity is triggered by the external electric field. On the other hand, the heterojunction device having a thick film of pZnP‐1 exhibits p‐type behavior at all the studied biases. Investigation of NH3 sensing properties of the heterojunction devices highlights the advantages of introducing pZnP‐1 in the heterostructures, which enhances the sensitivity, stability, repeatability, and humidity tolerance of the sensors.

Ruiqian Zhang, Binbin Qian, Ke Xu et al.

Transition metal sulfides (TMSs), characterized by their distinctive physicochemical properties, adjustable electronic structures, and compositional diversity, have gained significant attention as catalysts for electrochemical energy conversion. The transformation of electrocatalysts into highly active species during catalytic processes is a proven approach to significantly boost catalytic performance. Catalyst reconstruction via amorphization, ion doping, and phase transitions facilitates the formation of highly active species, markedly improving the electrocatalytic efficiency for OER and HER. Catalyst reconstruction modulates electronic structures, such as orbital occupancy, spin states, and band structures, to enhance intermediate adsorption and electron transport dynamics. This review highlights the latest progress in lattice reconstruction strategies for TMSs catalysts, emphasizing the interplay between orbitals, band structures, and lattice features with catalytic activity, and discusses the role of in situ techniques and theoretical modeling in developing next-generation high-performance electrocatalysts.

Qijun Lu, Jiawei Sun, Hao Zhang et al.

This paper presents a novel compact wideband quadruple-mode bandpass filter (BPF) with four resonant modes and five transmission zeros (TZs). Two T-shaped stepped impedance stub loaded resonators are coupled in parallel to the input and output feed lines to form the entire BPF. To provide a wideband and outstanding rejection in upper stopband, the two TZs are introduced by the stepped impedance stub as well as the designed coupling capacitor, and the two inherent TZs produced by the coupling between the resonators and feed lines are used and carefully tuned. The proposed BPF is fabricated in 65 nm CMOS technology with a core area of 0.072 mm² (7.1×10^-3 λ₀²). The measurement results show that the 3-dB bandwidth is 24.2 GHz at the center frequency of 94 GHz as well as the minimum insertion loss is 4.6 dB. Meanwhile, the stopband extends to 170 GHz with a stopband rejection above 25 dB.

María de Lourdes Rivas Becerra, Juan José Raygoza Panduro, Edwin Christian Becerra Alvarez et al.

This work presents the design of a system of a highly flexible pseudorandom number generator system (PRNG) incorporating both conventional and neuro-generators. The system integrates four internal generators with different conditions to produce new output sequences with adequate bits distribution and complexity. Two generators function at a frequency of 100 MHz with adjustable frequency settings, while two neuro-generators employ impulse neurons with distinct behaviours at 4 kHz, also modifiable. The proposed system meets 12 statistical randomness standards based on NIST’s (National Institute of Standards and Technology of U. S.) test suite, including the Frequency test, Binary Matrix Rank test, Linear Complexity test, and Random Excursion test, among others. Each resulted in a <i>P-value</i> greater than 0.01, confirming the pseudo-randomness of the generated sequences. The system is implemented on a reconfigurable device FPGA (Field Programmable Gate Array), with a low occupancy percentage, demonstrating its feasibility for various applications.

Chen Chen, Guang Cui, Jiawei Yang et al.

Abstract The demand for multinarrowband absorber has attracted increasing interest among researchers in recent years. However, integrating multifrequency absorption, tunability, and high optical transparency into an absorber remains a crucial challenge. In this study, a multiband, tunable, and transparent microwave meta‐absorber is theoretically proposed and experimentally demonstrated. This meta‐absorber is composed of resonant patterns made from graphene and indium tin oxide (ITO), placed on a substrate of lithium niobate (LN). By introducing P‐type doping to reduce the resistance of monolayer graphene to around 300 Ω, the impedance matching of the absorber is promoted, consequently manifesting ten absorption points within 40 GHz. The electric field distribution analysis and an equivalent circuit model are employed to elucidate the physical mechanisms of the multiband absorber. Additionally, the lithium niobate dielectric layer possesses a substantial dielectric constant and exhibits phase transition characteristics with temperature changes. When the temperature increases to 250 °C, a comprehensive tuning range of more than 5.49 GHz within 40 GHz range is realized. The maximum tuning range for a single frequency point is 1.33 GHz. With the broadening of the band, the meta‐absorber can provide multiple tunable ranges, making it more favorable for practical applications in optical modulator and sensor.

Ali Solgi, Anton Weissbach, Yahya Asl Soleimani et al.

Abstract Organic electrochemical transistors (OECTs) are gaining attention for their ease of fabrication, flexibility, and biocompatibility, with applications in biosignal sensing, neuromorphic computing, wearable health monitors, environmental monitoring, and bioelectronic interfaces. The interactions between ionic and electronic subcircuits in OECTs raise fundamental questions about the relationship between device design and performance. A major challenge is to meet specific integration, processing, and device performance requirements. While miniaturization of OECTs can improve transconductance and maximum operating frequency, it often compromises cost effectiveness and integratability. This work investigates an OECT architecture that incorporates both a crosslinkable printed aqueous electrolyte and a printed poly(3,4‐ethylenedioxythiophene):ploy(4‐styrenesulfonate) (PEDOT:PSS) top‐gate to achieve efficient gating, higher operating frequencies, and easy integration with low‐cost printing techniques. Improved performance is demonstrated in this top‐gate OECTs over conventional side‐gate structures, achieving sub‐millisecond device operation with channel lengths of 100 µm. This configuration shows practical potential for circuit integration, as demonstrated with a complementary inverter using an ambipolar material.

Tianyi Zhou, Ming Yang, Jingyao Wang et al.

Abstract On‐chip polarization photodetectors are crucial for advancing optical communication, which is facing the challenges of limited polarization sensitivity and hard on‐chip integration. 2D materials offer unique opportunities for creating high‐performance polarization photodetectors thanks to their intrinsic anisotropy and extensive heterostructure design freedom. Herein, a graphene/h‐BN/ReS2 tunneling heterostructure is designed to realize a high‐performance polarization photodetector in the Fowler−Nordheim tunneling (FNT) regime. Specifically, the photodetector achieves a high photocurrent signal‐to‐noise ratio of ≈103 by suppressing the tunneling dark current with the hBN tunneling layer. The h‐BN also creates a strong electric field, which accelerates the photogenerated carriers and achieves a response time of ≈70 µs. Such a high signal‐to‐noise ratio and short response time are over two orders of magnitude stronger and shorter than those of field‐effect transistor‐type ReS2 photodetectors. Moreover, in the FNT regime, the contribution of an anisotropic tunneling barrier and effective hole mass can effectively enhance the photocurrent dichroic ratio to exceed the intrinsic absorption dichroic ratio of 1.61, achieving the maximal value of 1.85. The enhancement mechanism is well understood by the consistent experimental and theoretical results. This study provides a viable approach to designing high‐performance on‐chip polarization photodetectors by utilizing the characteristics of the FNT regime.

Ta‐Shun Chou, Thi Thuy Vi Tran, Hartwin Peelaers et al.

Abstract In this work, the out‐diffusion and uphill‐diffusion of Mg inside (100) β‐Ga2O3 epilayers and substrates are reported. The Mg accumulates toward the (100) surface upon annealing under an oxidizing environment, whereas the concentration profile changes with annealing temperatures and durations. Furthermore, the out‐diffusion of Mg from the substrate into the epilayer is observed at temperatures above 800 °C, which continues during the film growth. The substitutional‐interstitial‐diffusion (SID) mechanism is suggested to be the driving mechanism for the former, and the latter is related to the diffusion of mobile Mg interstitials. The accumulation profile of Mg can be used to identify the interface between the epilayer and the substrate. Furthermore, significant differences in device performance are observed for power transistors fabricated on annealed and non‐annealed epitaxial β‐Ga2O3 wafers. Increased breakdown voltages of annealed samples are attributed to the Mg diffusion into the first few nanometers of the epitaxial layer close to the interface to the semi‐insulating substrate, leading to compensation of residual dopants (donors) in that region.

Ying Shen, Fa‐Hsyang Chen, Dongliang Yu et al.

Abstract This study investigates the effects of various ion implantation processes on the electrical performance of flexible low‐temperature polycrystalline silicon (LTPS) thin‐film transistor (TFT) backplanes. The introduction of BF2 ion implantation induces an additional shallow defect level near the valence band edge within the polycrystalline silicon band gap, as confirmed by deep‐level transient spectroscopy (DLTS). Simultaneously, this process reduces deep‐level traps within the band gap. Density functional theory (DFT) calculations further reveal that the BF2 clusters in polycrystalline silicon function as donors, effectively passivating defect states within the TFT channel. This effect contributes to the observed reduction in deep‐level traps. Consequently, BF2‐doped TFT channels exhibit a lower density of deep‐level traps, leading to enhanced electrical stability of the TFT devices under continuous electrical stress. As a result, AMOLED displays driven by these stabilized TFT backplanes demonstrate reduced image sticking and improved image quality. The above achievements provide a systematic methodology that combines experimental analysis and theoretical model calculation for the in‐depth exploration of the intrinsic mechanisms of device performance in the display industry.

Xiaoning Wang, Ming Zeng, Dazhang Li et al.

Plasma wakefield acceleration holds remarkable promise for future advanced accelerators. The design and optimization of plasma-based accelerators typically require particle-in-cell simulations, which can be computationally intensive and time consuming. In this study, we train a neural network model to obtain the on-axis longitudinal electric field distribution directly without conducting particle-in-cell simulations for designing a two-bunch plasma wakefield acceleration stage. By combining the neural network model with an advanced algorithm for achieving the minimal energy spread, the optimal normalized charge per unit length of a trailing beam leading to the optimal beam-loading can be quickly identified. This approach can reduce computation time from around 7.6 minutes in the case of using particle-in-cell simulations to under 0.1 seconds. Moreover, the longitudinal electric field distribution under the optimal beam-loading can be visually observed. Utilizing this model with the beam current profile also enables the direct extraction of design parameters under the optimal beam-loading, including the maximum decelerating electric field within the drive beam, the average accelerating electric field within the trailing beam and the transformer ratio. This model has the potential to significantly improve the efficiency of designing and optimizing the beam-driven plasma wakefield accelerators.

Farzin Asadi

Pengcheng Liu, Zhenghang Hao, Zhuo Chen et al.

In order to realize the real-time electromagnetic transient simulation of grid-connected photovoltaic power generation system with small time step, a heterogeneous multiplexed parallel real-time simulation method based on field programmable gate array (FPGA) and central processor is studied. According to the simulation accuracy requirements of the high and low frequency decoupling module, a differentiated simulation step size is used to solve the problem, and a 1us/50us FPGA-CPU multi-rate real-time simulation platform is constructed, in which the FPGA simulation part meets the real-time requirements of small-step transient simulation through the optimization of the response matching method and the EMTP algorithm, the offline simulation results are compared with Simulink, and the model before and after optimization is analyzed, the real-time electromagnetic transient simulation results are compared with Simulink, and the model before and after optimization is analyzed. By comparing the offline simulation results with Simulink and analyzing the FPGA resource consumption before and after model optimization, the accuracy and real-time performance of the co-simulation method for real-time simulation of grid-connected photovoltaic systems are verified.

Chaoyu Zhang, Qi Jia, Yijie Liu et al.

The research refers to the features of production-living-ecological land use transformation in the Zhengzhou metropolitan area from 1990 to 2020, applies the PLUS (patch-generating land use simulation) model and ESV(Ecosystem Service Value)accounting to set three scenarios, and analyzes the spatiotemporal features of ecosystem service value via multi-scenario simulation, aiming to provide technical support to territorial spatial planning and ecological restoration. The results show that: (1) From 1990 to 2020, agricultural production land has the highest transform volume; the supply, regulation, and cultural services along the Yellow River continued to increase, while support services continued to decrease in the metropolitan areas of Zhengzhou and Xinzheng. (2) Compared with 2020, the supply and regulation services under the ecological protection scenario show an upward trend, and the comprehensive benefits of ecosystem services reach the best. (3) The ecological protection scenario reduces the probability of converting ecological land into living land, making the total ESV grow constantly.

Hasibullah Khan

Aim: Considering the consequences of climate change, architects must consider how their designs may affect both interior and outdoor thermal comfort. Method: ologies: Examining various design possibilities regarding biometeorological characteristics is made possible by new microclimate analysis technologies that are becoming more popular among architects. Architects and designers can automate complex design processes and generate dynamic geometries through the incorporation of Grasshopper, a visual scripting plugin for Rhino, and Dynamo, a visual programming tool for Revit. By integrating these tools, designers can construct parametric models that respond to various environmental factors, such as solar radiation, wind flow, thermal comfort, and daylight availability. Findings: The article discusses an architectural design firm's recent efforts to use local climate challenges as design inspiration. Rhino and Revit, respectively, two architectural engineering construction (AEC) software, interacted to produce open source platforms like Grasshopper and Dynamo. These new instruments have made modern biometeorological parameters more accessible for experimentation and design. Limitations: Most of the available resources for developing climatic modeling were designed for study and lack optimization for architecture and urban designing; as a result, they require changes to enhance their usability or achieve interoperability with commonly used software by architects. It provides Python scripts that produce climatic boundary conditions for microclimate simulations and extract design-consequential data from simulated results. Conclusion: This study outlines the difficulties encountered when incorporating microclimate analysis into design practice as well as the methods used to get through these roadblocks.

Jiong Pan, Zeda Wang, Bingchen Zhao et al.

With the development of artificial intelligence and edge computing, the demand for high-performance non-volatile memory devices has been rapidly increasing. Two-dimensional materials have ultrathin bodies, ultra-flattened surfaces, and superior physics properties, and are promising to be used in non-volatile memory devices. Various kinds of advanced non-volatile memory devices with semiconductor, insulator, ferroelectric, magnetic, and phase-change two-dimensional materials have been investigated in recent years to promote performance enhancement and functionality extension. In this article, the recent advances in two-dimensional material-based non-volatile memory devices are reviewed. Performance criteria and strategies of high-performance two-dimensional non-volatile memory devices are analyzed. Two-dimensional non-volatile memory array structures and their applications in compute-in-memory architectures are discussed. Finally, a summary of this article and future outlooks of two-dimensional non-volatile memory device developments are given.

Jiayun Xiang, Gaoqing Cao

Very strong electromagnetic field can be generated in peripheral relativistic heavy ion collisions. This work is devoted to exploring the interplay between the effects of a constant external electric field and confining potential on heavy-flavor mesons. As the corresponding vector potential linearly depends on one spatial coordinate for a constant electric field, it might be able to overcome the linear confining potential of QCD and induce deconfinement. To perform analytic calculations and for comparison, one and two dimensional systems are studied together with the realistic three dimensional systems. The one dimensional Schr$\ddot{\text o}$dinger equation can be solved analytically with the help of Airy functions, and deconfinement is indeed realized when the electric field is larger than the string tension. Focus on the confining case, the two and three dimensional Schr$\ddot{\text o}$dinger equations can be solved analytically in large $r$ limit with the help of elliptic cosine/sine functions, and the wave functions are dominated by the region antiparallel to the electric field. When a more realistic potential is applied, a non-monotonic feature is found for $Υ(2S)$ and $Υ(3S)$-like mesons with increasing electric field.

Ahmed Gailani, Peter Taylor

Decarbonising the industrial sector is vital to reach net zero targets. The deployment of industrial decarbonisation technologies is expected to increase industrial electricity demand in many countries and this may require upgrades to the existing electricity network or new network investment. While the infrastructure requirements to support the introduction of new fuels and technologies in industry, such as hydrogen and carbon capture, utilisation and storage are often discussed, the need for investment to increase the capacity of the electricity network to meet increasing industrial electricity demands is often overlooked in the literature. This paper addresses this gap by quantifying the requirements for additional electricity network capacity to support the decarbonisation of industrial sectors across Great Britain (GB). The Net Zero Industrial Pathways model is used to predict the future electricity demand from industrial sites to 2050 which is then compared spatially to the available headroom across the distribution network in GB. The results show that network headroom is sufficient to meet extra capacity demands from industrial sites over the period to 2030 in nearly all GB regions and network scenarios. However, as electricity demand rises due to increased electrification across all sectors and industrial decarbonisation accelerates towards 2050, the network will need significant new capacity (71 GW + by 2050) particularly in the central, south, and north-west regions of England, and Wales. Without solving these network constraints, around 65% of industrial sites that are large point sources of emissions would be constrained in terms of electric capacity by 2040. These sites are responsible for 69% of industrial point source emissions.

Mostafa Mohammadian, Kyri Baker, Ferdinando Fioretto