Bias Conditions Research Articles

Zigzag boron nitride nanoribbon doped with carbon atom for giant magnetoresistance and rectification behavior based nanodevices

Using the principles of density functional theory (DFT) and nonequilibrium Green’s function (NEGF), We thoroughly researched carbon-doped zigzag boron nitride nanoribbons (ZBNNRs) to understand their electronic behavior and transport properties. Intriguingly, we discovered that careful doping can transform carbon-doped ZBNNRs into a spintronic nanodevice with distinct transport features. Our model showed a giant magnetoresistance (GMR) up to a whopping 105\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^5$$\\end{document} under mild bias conditions. Plus, we spotted a spin rectifier having a significant rectification ratio (RR) of 104\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^4$$\\end{document}. Our calculated transmission spectra have nicely explained why there’s a GMR up to 105\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^5$$\\end{document} for spin-up current at biases of -1.2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-1.2$$\\end{document} V, -1.1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-1.1$$\\end{document} V, and -1.0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-1.0$$\\end{document} V, and also accounted for a GMR up to 103\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^3$$\\end{document}–105\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^5$$\\end{document} for spin-down current at biases of 1.0 V, 1.1 V, and 1.2 V. Similarly, the transmission spectra elucidate that at biases of 1.0 V, 1.1 V, and 1.2 V for spin-up, and at biases of 1.1 V and 1.2 V for spin-down in APMO, the RRs reach 104\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^4$$\\end{document}. Our research shines a light on a promising route to push forward the high-performance spintronics technology of ZBNNRs using carbon atom doping. These insights hint that our models could be game-changers in the sphere of nanoscale spintronic devices.

Performance study of microwave photonic links by considering the effect of phase shifters and bias conditions on dual-drive dual parallel Mach–Zehnder modulator

Abstract This paper presents the performance analysis of different schemes for generating linearized photonic signal by varying phase shifter arrangements of a dual-drive dual parallel Mach–Zehnder modulator (DD-DPMZM). The RF signals at the electrodes of sub-modulators of DD-DPMZM are fed using different phase angles to generate optically modulated signals in the output. The proposed system consists of a DD-DPMZM and phase shifters. Spurious free dynamic range (SFDR) is evaluated for different configurations of sub modulators in upper and lower arm of DD-DPMZM. SFDR of 135.6 dB Hz4/5 is obtained for quadrature and optical carrier suppression modulation in upper and lower submodulators by suppressing third order intermodulation distortion completely. It is found to be high performance configuration for dual parallel Mach–Zehnder modulator based linear microwave photonic link.

Multi-functional metasurface as a transmissive/reflective FSS and an on-air frequency mixer

In this paper, a multi-functional metasurface is proposed, which can work as a narrowband transmissive/reflective frequency selective surface (FSS) and an on-air frequency mixer based on its switching response. The metasurface is made up of unit cells with square and circular metallic loops connected by PIN diodes controlled by a bias source. In contrast to typical wideband FSSs, the structure provides 0.55 GHz of narrow stopband (a fractional bandwidth of 22%) at 2 GHz in the OFF state bias. The bandstop response can be adjusted by varying the reverse bias voltage. The metasurface alternates between its functionalities when in forward bias by providing a passband at the operational frequency. The structure is compact and operates as a transmissive/reflective surface under two different bias conditions (ON and OFF). The design is angularly stable and polarization-insensitive for both TE and TM polarisation. A prototype of the designed structure is developed and the measured results correlate well with the simulated responses from the finite-difference time-domain (FDTD) method-based simulation of the circuit model. On-air frequency mixing for a wave propagating through the metasurface is demonstrated and the effects of different parameters affecting the mixing are parametrically studied through FDTD simulations and experiments.

Interfacial thermal resistance effect in self-aligned top-gate a-IGZO thin film transistors

This study investigates the interfacial thermal resistance effect, primarily associated with the bottom-gate stack, in self-aligned top-gate amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs). We analyze self-heating and heat transfer characteristics across three different a-IGZO TFT configurations: single-gate, dual-gate type 1, and dual-gate type 2. Temperature maps, corresponding to various bias conditions, are acquired using infrared thermal microscopy. The extracted values of thermal resistance reveal a significant disparity between single- and dual-gate configurations. This suggests that the bottom-gate stack in a-IGZO TFTs, including the interfaces, notably impedes heat dissipation. These findings offer crucial insights into the power dissipation aspects of TFT technology, highlighting the importance of interfacial design for thermal management in advanced electronic devices.

Reactive DC Sputtered TiO2 Electron Transport Layers for Cadmium‐Free Sb2Se3 Solar Cells

AbstractThe evolution of Sb2Se3 heterojunction devices away from CdS electron transport layers (ETL) to wide bandgap metal oxide alternatives is a critical target in the development of this emerging photovoltaic material. Metal oxide ETL/Sb2Se3 device performance has historically been limited by relatively low fill factors, despite offering clear advantages with regards to photocurrent collection. In this study, TiO2 ETLs are fabricated via direct current reactive sputtering and tested in complete Sb2Se3 devices. A strong correlation between TiO2 ETL processing conditions and the Sb2Se3 solar cell device response under forward bias conditions is observed and optimized. Numerical device models support experimental evidence of a spike‐like conduction band offset, which can be mediated, provided a sufficiently high conductivity and low interfacial defect density can be achieved in the TiO2 ETL. Ultimately, a SnO2:F/TiO2/Sb2Se3/P3HT/Au device with the reactively sputtered TiO2 ETL delivers an 8.12% power conversion efficiency (η), the highest TiO2/Sb2Se3 device reported to‐date. This is achieved by a substantial reduction in series resistance, driven by improved crystallinity of the reactively sputtered anatase‐TiO2 ETL, whilst maintaining almost maximum current collection for this device architecture.

CVD-Grown Monolayer MoS2 and GaN Thin Film Heterostructure for a Self-Powered and Bidirectional Photodetector with an Extended Active Spectrum.

Photodetector technology has evolved significantly over the years with the emergence of new active materials. However, there remain trade-offs between spectral sensitivity, operating energy, and, more recently, an ability to harbor additional features such as persistent photoconductivity and bidirectional photocurrents for new emerging application areas such as switchable light imaging and filter-less color discrimination. Here, we demonstrate a self-powered bidirectional photodetector based on molybdenum disulfide/gallium nitride (MoS2/GaN) epitaxial heterostructure. This fabricated detector exhibits self-powered functionality and achieves detection in two discrete wavelength bands: ultraviolet and visible. Notably, it attains a peak responsivity of 631 mAW-1 at a bias of 0V. The device's response to illumination at these two wavelengths is governed by distinct mechanisms, activated under applied bias conditions, thereby inducing a reversal in the polarity of the photocurrent. This work underscores the feasibility of self-powered and bidirectional photocurrent detection but also opens new vistas for technological advancements for future optoelectronic, neuromorphic, and sensing applications.

Planar deposition of Nb thin films by HiPIMS for superconducting radiofrequency applications

Cost efficiency and sustainability are critical challenges for future accelerator machines. Nb-coated Cu (Nb/Cu) superconducting radiofrequency (SRF) accelerating cavities, while requiring R&D to meet high acceleration gradient performance standards, show potential for addressing these challenges. Defects in the Nb layer responsible for the deterioration of cavity performance have been linked to the underlying Cu substrate. This study investigates a novel optimization method by mitigating the substrate surface’s impact on deposited Nb, using High Power Impulse Magnetron Sputtering alongside a DC substrate bias (from −50 to −300 V). Trenched silicon substrates are chosen to emulate substrates with exceptionally rugged surface characteristics. Film deposition is investigated both experimentally and through kinetic Monte Carlo simulations. Higher DC voltages are shown to eliminate self-shadowing during the coating process via improved incident ionic flux directionality, enhanced adatom mobility and increased re-sputtering rates, ultimately yielding flat and densely-packed films. The influence of the substrate’s shape on the film’s surface was found to decrease exponentially with increasing ion bombardment energies. Films sputtered under high DC bias conditions (−300 V) exhibited complete planarization with a 30% re-sputtering rate. Strategies for applying this technique to Nb/Cu SRF cavities, enhancing their viability for future particle accelerators, are also discussed.

The influence of the gap width of the blade on the performance of the mixing pump

Abstract The spiral axial flow gas-liquid mixed pump has some problems, such as unsteady flow and sharp decline in performance, when it runs in the biased condition with high gas content. Based on the principle of fluid flow and the design concept of slot drainage, a slit blade is proposed in this study to improve the degree of gas-liquid separation inside the mixing pump. The slit connects the pressure surface of the blade of the mixing pump with the suction surface. The pressure difference between the pressure surface and the suction surface leads to the generation of slit jet, which plays a “blowing” role in the adhesion of the gas phase on the suction surface inside the mixing pump. And make the stagnant air mass in the flow passage move again, so as to slow down the gas-liquid separation in the mixed transport pump. This study provides theoretical reference for the design and optimization of spiral axial flow gas-liquid mixed pump.

Assessment of 180 nm double SOI technology for analog front-end design with back-gate voltage

This paper provides an assessment of the electrical and noise performance in the 180 nm double silicon-on-insulator (DSOI) technology, which shows advantages for analog front-end radiation detectors. For the first time, the impact of the back-gate voltage on the electrical and noise performance of DSOI MOSFETs is investigated. The transconductance-to-current (gm /ID ) ratio and low-frequency (1/f) noise were measured as a function of the MOS device types (NMOS/PMOS), gate length, and bias condition of front- and back-gates. Experimental results show that positive back-gate voltage deteriorates the gm /ID ratio of the MOSFETs in weak inversion region. The DSOI NMOS devices overwhelm the PMOS with better gm /ID and 1/f performance. The DSOI devices have a comparable 1/f noise with the 180 nm SOI counterparts. With negative back-gate voltage applied, the low frequency noise performance of NMOS is improved. This assessment of DSOI technology gives a guideline for the readout circuit design in detector front-end systems.

26‐3: Room Temperature Bias‐Selectable, Dual‐Band Ultraviolet/Infrared Detectors Based on PTAA/MAPbCl3 Single Crystal film Heterojunction

A single photodetector capable of switching its peak spectral photoresponse between two wavelength bands is highly useful, particularly for the ultraviolet‐infrared bands in applications such as remote sensing, object identification, and chemical sensing. However, it is difficult to realize dual‐frequency ultraviolet/infrared detection with the existing technology. In this study, we leverage the advantages of perovskites materials to demonstrate a bias‐selectable ultraviolet/infrared dual‐band detector that operates at room temperature by using CH3NH3PbCl3 (MAPbCl3) single ctystal film and poly(triaryl amine). By switching between zero and forward bias, this detectors switch peak photosensitive ranges between the ultraviolet and infrared bands with room temperature detectivities of 4.5 × 1012 and 1.65 × 10 9 cm Hz 1/2 W −1, respectively. Unlike conventional bias‐selectable detectors, which utilize a set of back‐to‐back photodiodes, we demonstrate that under zero/forward bias conditions the device's operation mode instead changes between photovoltaic effect and photoconductive effect / the radiant thermal effect, allowing additional functionalities that the conventional structure cannot provide.

Enhanced performance of normally-OFF GaN HEMTs with stair-shaped p-GaN cap layer

The p-GaN-gated E-mode HEMTs (P-HEMTs) are being extensively studied for emerging power electronics. However, the devices still suffer from performance trade-off among threshold voltage (V TH), output drain current (I DS), and breakdown voltage (V BD). Herein, we propose a P-HEMT with a stair-like p-GaN cap layer to boost their performance. The p-GaN cap layer is composed of four discrete p-GaN staircases with the decreased thickness to the right (Right-Stair P-HEMT) or to the left (Left-Stair P-HEMT). It is found that the RSP-HEMT simultaneously achieves the 1.3 times increased I DS, 160 V enhanced V BD, and improved V TH stability against drain-induced barrier lowering effects, compared with the LSP-HEMT and the conventional BaSeline P-HEMT. These device merits should be attributed to the effective manipulation of the lateral electric field (E F) under all bias conditions by the unique band structures enabled by the RSP configuration. Such E F manipulation strategies offer us helpful guidance and insights to further propel the development of high-performance E-mode P-HEMTs.

Numerical investigation on the convergence of self-consistent Schrödinger-Poisson equations in semiconductor device transport simulation

Semiconductor devices at the nanoscale with low-dimensional materials as channels exhibit quantum transport characteristics, thereby their electrical simulation relies on the self-consistent solution of the Schrödinger-Poisson equations. While the non-equilibrium Green’s function (NEGF) method is widely used for solving this quantum many-body problem, its high computational cost and convergence challenges with the Poisson equation significantly limit its applicability. In this study, we investigate the stability of the NEGF method coupled with various forms of the Poisson equation, encompassing linear, analytical nonlinear, and numerical nonlinear forms Our focus lies on simulating carbon nanotube field-effect transistors (CNTFETs) under two distinct doping scenarios: electrostatic doping and ion implantation doping. The numerical experiments reveal that nonlinear formulas outperform linear counterpart. The numerical one demonstrates superior stability, particularly evident under high bias and ion implantation doping conditions. Additionally, we investigate different approaches for presolving potential, leveraging solutions from the Laplace equation and a piecewise guessing method tailored to each doping mode. These methods effectively reduce the number of iterations required for convergence.

Self-Powered cobalt nanocluster decorated flexible graphene based Tribo-Sensors for respiratory diagnosis of critical asthma patient

Self-powered ultrafast sensors have received much attention for sustainable operation without any external power source in the Internet of Things (IoT) platform. This paper proposes faster responsive, highly sensitive triboelectric nanogenerator (TENG) sensors based on few layered nitrogen-doped graphene anchored with cobalt nanocluster (Co-N-Gr) to detect the relative concentration of target species, their proximity analysis, and monitor malfunction of human respiration in real-time. Herein, to understand the sensing mechanism, P-type behaviour of this active material is verified under the FET platform by reducing the leakage current density via the implementation of dual dielectric gate (NiO (200 nm)-SiO2 (10 nm)) oxides leading to better control over channel mobility. The device exhibits maximum sensitivity of around 4722 % at zero bias conditions with excellent response and recovery time of 1.16 s and 1.39 s, respectively which falls within the range of standard human breathing frequency. The triboelectric nature of the sensor device at 1 V bias under natural breathing exhibits a high sensitivity (39.56 %) towards relative humidity of 10–90 % with excellent stability over 13 h. In addition, our TENG sensor is highly sensitive towards NOx content upto ppb levelwhich can improve reliability towards asthma detection as NOx content is relatively higher in asthma patients. This approach provides an integrated platform not only towards selective detection of NOx content as well as to identify the individual breathing strength. Furthermore, as-fabricated self-powered device demonstrates its potential in differentiating various respiratory status and has the capability to detect acute exacerbation of chronic obstructive pulmonary disease (AECOPD) via a distinct pattern recognition. Therefore, the work paves the way to design a low-cost flexible device fabrication on Kapton substrate integrable with wearable appliances for commercialization.

Multi-channel polarization manipulation based on graphene for encryption communication

Wave-based cryptography, at the vanguard of advancing technologies in advanced information science, is essential for establishing a diverse array of secure cryptographic platforms. The realization of these platforms hinges on the intelligent application of multiplexing techniques, seamlessly combined with appropriate metasurface technology. Nevertheless, existing multi-channel encryption technologies based on metasurfaces face challenges related to information leakage during partial channel decoding processes. In this paper, we present a reprogrammable metasurface for polarization modulation. This metasurface not only allows for the arbitrary customization of linearly polarized reflected waves but also enables real-time amplitude modulation. Here, relying on polarization amplitude control, a fully secure communication protocol is developed precisely in the terahertz (THz) spectrum to achieve real-time information encryption based on polarization modulation metasurfaces where access to information is highly restricted. The proposed metasurface employs the double random phase encryption (DRPE) algorithm for information encryption. It transmits the encrypted data through different polarization channels using two graphene nanoribbons, exclusively controlled by external biasing conditions. Various encryption scenarios have been outlined to fortify information protection against potential eavesdroppers. The simulated results show that this unique technology for hiding images by manipulating the polarization of the reflected wave provides new opportunities for various applications, including encryption, THz communications, THz secure data storage, and imaging.

Enhancing performance of SnS2 based self-powered photodetector and photocatalyst by Na incorporation

Sn and S are environmentally friendly elements that are abundant in nature. The SnS2 compound formed with these elements has intrinsic n-type electrical conductivity and a direct forbidden band gap of ∼2.2 eV. Therefore, it is a very promising compound for visible light optoelectronic applications. In this study, SnS2thin films were coated on p-Si substrates and pn heterojunction structures were obtained. By adding certain amounts of Na element to SnS2, the photosensitivity of the heterojunction devices increased tremendously and reached a high value of 3.2 × 104 under zero bias condition. It was observed that the prepared devices had excellent speeds and stability with rise and decay times of as low as 28 m s and 23 m s. Moreover, the devices were found to be sensitive to visible light even at ultra-low light intensity of ∼0.3 μW/cm2. Furthermore, the responsivity and specific detectivity values of the prepared photodetectors reach very high values of 11 A/W and 8.4 × 1013 Jones at this low light intensity. The NEP value drops to a low level of 2.7 × 10−15 WHz −1/2. In addition, the photocatalytic properties of Na-doped and undoped SnS2 compound were also examined under visible LED light. Compared to undoped samples, photocatalytic efficiency increased by ∼42 % in Na-doped SnS2 thin films. The findings clearly reveal that Na improves both photodetector device performance and the photocatalytic effect of the SnS2 semiconductor.

WITHDRAWN: Vacancies and antisites investigation at InAlAs/InGaAs hetero-interface: A first-principles study

The vacancies and antisites at InAlAs/InGaAs hetero-interface have been investigated by first-principles calculation based on hybrid density functional (HSE06). We propose an approach to obtain the chemical potentials based on the growth process of hetero-junction. The valence-band maximum of hetero-interface supercell is aligned with the reference of the average electrostatic potential of bulk material. The VIn, VGa, and VAl defects are deep acceptors, while VAs-1, VAs-2, and VAs-3 defects would behave as donor defects. The antisites are amphoteric defects, whereas they will only behave as donor defects due to the Fermi-level should be below the conduction-band minimum of InGaAs side. For InAlAs/InGaAs devices, the impact of the cation vacancies (acceptors) and antisites (donors) is associated to the bias conditions, while it is bias-independent for As vacancies (donors).

Associations Between Neighborhood Resources and Youths’ Response to Reward Omission in a Task Modeling Negatively Biased Environments

Neighborhoods provide essential resources (eg, education, safe housing, green space) that influence neurodevelopment and mental health. However, we need a clearer understanding of the mechanisms mediating these relationships. Limited access to neighborhood resources may hinder youths from achieving their goals and, over time, shape their behavioral and neurobiological response to negatively biased environments blocking goals and rewards. To test this hypothesis, 211 youths (aged ∼13.0 years, 48% boys, 62% identifying as White, 75% with a psychiatric disorder diagnosis) performed a task during functional magnetic resonance imaging. Initially, rewards depended on performance (unbiased condition); but later, rewards were randomly withheld under the pretense that youths did not perform adequately (negatively biased condition), a manipulation that elicits frustration, sadness, and a broad response in neural networks. We investigated associations between the Childhood Opportunity Index (COI), which quantifies access to youth-relevant neighborhood features in 1 metric, and the multimodal response to the negatively biased condition, controlling for age, sex, medication, and psychopathology. Youths from less-resourced neighborhoods responded with less anger (p< .001, marginal R2= 0.42) and more sadness (p< .001, marginal R2= 0.46) to the negatively biased condition than youths from well-resourced neighborhoods. On the neurobiological level, lower COI scores were associated with a more localized processing mode (p= .039, marginal R2= 0.076), reduced connectivity between the somatic-motor-salience and the control network (p= .041, marginal R2= 0.040), and fewer provincial hubs in the somatic-motor-salience, control, and default mode networks (all pFWE< .05). The present study adds to a growing literature documenting how inequity may affect the brain and emotions in youths. Future work should test whether findings generalize to more diverse samples and should explore effects on neurodevelopmental trajectories and emerging mood disorders during adolescence. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented racial and/or ethnic groups in science. One or more of the authors of this paper self-identifies as a member of one or more historically underrepresented sexual and/or gender groups in science. One or more of the authors of this paper received support from a program designed to increase minority representation in science. We actively worked to promote sex and gender balance in our author group. We actively worked to promote inclusion of historically underrepresented racial and/or ethnic groups in science in our author group.

Why the racing industry and equestrian disciplines need to implement population pharmacokinetics: To learn, explain, summarize, harmonize, and individualize.

Population pharmacokinetics (POP PK) is a powerful pharmacokinetic tool, which measures quantitatively, and explains the variability in drug exposure and drug effect between individuals. POP PK uses an observational (nonexperimental) approach; it is conducted in the target population living in its normal environment (e.g., farm and race-track). The strength of the POP PK approach lies in its greater relevance for the population studied in its different natural environments than experimental studies carried out in more or less biased laboratory conditions. In clinical settings, it is commonly necessary to restrict the number of samples per subject collected for analysis and the derived data cannot be analyzed using traditional individual data analytical methods; rather data are merged and analyzed with an appropriate statistical tool: the nonlinear mixed effect model (NLMEM). POP PK modeling is frequently used with the objective of adjusting drug dosage, and hence drug exposure, not only for the whole population but also for subgroups of animals (e.g., for a given breed, sex, and age). It can also have application at the individual subject level, in the context of precision medicine. For horses, the use of the POP PK/PD model will allow prescribers to estimate an individual Withdrawal Time for a given horse whose treatment they are supervising. Another potential field of application will be meta-analysis of existing data to generate new knowledge on a drug or to collate and synthesize, in an objective and transparent manner, existing data; this will facilitate harmonization of screening limits at an international level.

2D MoS2 monolayers integration with metal oxide-based artificial synapses

In this study, we report on a memristive device structure wherein monolayers of two-dimensional (2D) molybdenum disulfide (MoS2) are integrated with an ultrathin yttrium oxide (Y2O3) layer to simulate artificial synapses functionality. The proposed physical simulation methodology is implemented in COMSOL Multiphysics tool and is based on the minimization of free energy of the used materials at the applied input voltage. The simulated device exhibits a stable bipolar resistive switching and the switching voltages is significantly reduced by increasing the number of MoS2 layers, which is key to conventional low-power computing and neuromorphic applications. The device is shown to perform synaptic functionalities under various applied bias conditions. The resulting synaptic weight decreases almost linearly with the increasing number of MoS2 layers due to the increase in the device thickness. The simulation outcomes pave the way for the development of optimised metal oxide-based memristive devices through their integration with semiconducting 2D materials. Also, the 2D MoS2 integration can enable the optoelectronic operation of this memory device.

A comparative study of J–A and Preisach improved models for core loss calculation under DC bias

Power transformer is widely used in the power system with the rapid development of the power converters connected to the grid. When a transformer operates under DC bias conditions, its iron core loss increases significantly, causing local overheating and threatening the proper operation of the transformer. However, there are persistent difficulties in accurately assessing the core loss when the induction waveform is influenced by a DC bias. This paper first proposes improvements to the J–A and Preisach models to evaluate the core loss of the iron core under DC bias. Additionally, we incorporate the hysteresis models into the finite element method (FEM) by modifying the fundamental constitutive equations in the FEM model in order to perform a precise core loss/distribution calculation. To verify the accuracy of prediction, a transformer prototype with a laminated core is developed. The improved J–A-FEM and Preisach-FEM models were directly compared in terms of calculation accuracy, numerical implementation, and computational burden.