Electric Surface Research Articles

Analytical Modeling and TCAD simulation of Surface Potential and Drain Current for Pocket Doped Negative Capacitance Field-Effect Transistor

Abstract In this work, a 2D analytical model for a Highly Doped Double Pocket Double Gate NCFET (HDDP-DG-NCFET) device has been developed. The framework of the model is derived from the Poisson’s equation, LK equation and solved utilizing appropriate boundary conditions. The developed model is projected for several device variables, including electric field, surface potential and drain current.
Afterward, to verify the model’s accuracy, Sentaurus TCAD has been utilized for device simulation, and a good agreement with 85–95% precision is witnessed. The comprehensive and structured analysis of device is provided by examining variations in dimensions of device, ferroelectric material and oxide materials. The presented analysis shows that, the proposed HDDP-DG-NCFET device has significant potential for low power applications.

Transverse-Electric Surface Plasmon in Graphene Under Uniform Strain

Abstract Compared to surface plasmon polariton in metals, graphene can support transverse electric (TE) surface modes when the imaginary part of its conductivity is negative. TE graphene plasmons are generally weakly confined in direction perpendicular to the graphene plane, and they cannot be resonantly excited by an external incident wave because their dispersion curve spectrally lies just below the light line. In this work, we investigate theoretically the light reflectance of a graphene layer under uniform strain on the top of a one-dimensional photonic crystal consisting of high and low-index dielectric materials and a material film layer on the graphene sheet. The strain not only changes the electronic band structure but also can be employed to influence the electronic collective excitations and thus the optical reflectance of graphene monolayers. We demonstrate that TE plasmon excitation is based on the observation of a pronounced sharp minimum in the reflection coefficient of the suggested photonic structure upon the incident angle, the wavelength, and refractive index. Therefore, the graphene under uniform strain on the photonic structure is found to be promising in the fabrication of optical sensors devices with TE plasmons.

Lattice Boltzmann modeling of droplet actuation via temperature gradient and electrowetting

Droplet manipulation under various physical fields is crucial for microfluidics. Theoretical models are key to understand the physics. In this work, by extending the binary phase lattice Boltzmann model to fully coupled thermodynamics and electrostatics, we systematically explore the behaviors of droplet transport driven by temperature-dependent surface tension, thermocapillary, and electrowetting effects. It is shown that electrowetting enables bidirectional transport of the droplet, determined by various physical parameters such as electric voltage, wettability, viscosity, thermal conductivity, and surface tension. Specifically, the physics revealed in this work is more than simply electrowetting modified wettability. Actually, the droplet transport is controlled further by contact angle hysteresis and thermocapillary-induced temperature gradient.

Weight-Based Distributed Flocking Control for Multiple Electric Marine Surface Vehicles Under Fully Intermittent Communications

Weight-Based Distributed Flocking Control for Multiple Electric Marine Surface Vehicles Under Fully Intermittent Communications

Synthesis of semi sintered nickel bronze electrode for electric discharge surface alloying of silicon steel and the properties of coated surface

Synthesis of semi sintered nickel bronze electrode for electric discharge surface alloying of silicon steel and the properties of coated surface

Adhesion characteristics of carbon particles on the surface of epoxy resin in insulating oil under DC electric field and influencing factors

AbstractThe adhesion of carbon particles on the surface of epoxy resin in insulating oil is a significant factor contributing to surface flashover. However, there is currently a lack of a dynamic model that can reasonably explain the adhesion process of impurity particles, and the characteristics of particle adhesion are not yet clear, making it difficult to assess the risks of insulation contamination and surface flashover of valve‐side bushing capacitance core. In this study, based on the Johnson–Kendall–Roberts (JKR) theory and the normal distribution characteristics of particle charges, the adhesion probability model of conductive particles in insulating oil on the surface of epoxy resin under DC electric fields was established, and carbon particle adhesion experiments were conducted to verify the accuracy of the model. The impact of electric field intensity, particle size, particle charge, and surface energy of the insulation material on the adhesion characteristics of carbon particles was investigated using the proposed model. The results can be utilised for the assessment of insulation contamination risks of valve‐side bushing capacitance core and serves as a vital theoretical foundation for guiding the optimisation of anti‐contamination structures in internal insulation and the development of advanced pollution‐resistant and flashover‐resistant insulation materials.

New surface waves in a hyperbolic graded-index crystal

The transverse electric surface waves propagating along the surface of the crystal characterized by a spatial dependence of the dielectric permittivity are theoretically described. A hyperbolic profile of the dielectric permittivity of the crystal is used to obtain an exact analytical solution to the wave equation, which is expressed by Whittaker function. The influence of the parameters of the hyperbolic profile of the dielectric constant on the localization of the electric field near the crystal surface is analyzed. The dependencies of the effective refractive index on the parameters of a hyperbolic profile of the dielectric permittivity are explored. The way to effectively control the localization and intensity of the surface waves by changing the values of the parameters of the hyperbolic profile using the obtained exact solution is found.

An efficient method of moments for analysis of electromagnetic scattering from a multilayered arbitrary‐shape anisotropic dielectric object

AbstractThis paper introduces an efficient method of moments (MoM) designed to explore electromagnetic scattering in multilayered anisotropic structures. Each layer is made up of a dielectric anisotropic material characterised by a generalised tensor for permittivity, which is unrestricted in its geometrical configuration. The authors’ approach analyses each layer independently, employing the surface equivalence theorem to substitute the interfaces between layers with suitable equivalent electric and magnetic surface current densities. The authors derive the necessary surface integral equations (SIEs) for each interface by implementing the proper boundary conditions. The analysis utilises rotated dyadic Green's functions that populate the infinite space with the material properties specific to each anisotropic layer. The rotation angle corresponds to the deviation between the local principal coordinate system of the material and the global coordinate system, which is determined by diagonalising the full dielectric tensor of the respective anisotropic material given in the global coordinate system. To address the SIEs for determining the unknown equivalent electric and magnetic surface current densities, Galerkin's MoM is applied. This involves expanding the unknown surface currents using suitable basis functions, simplifying the issue to a matrix equation solved through the inversion of a block‐tridiagonal impedance matrix. The diagonal nature and sparse structure of the impedance matrix, along with an effective block‐inversion method, significantly boost computational efficiency and reduce memory demands. To demonstrate the feasibility of the proposed method, the authors present a detailed derivation of the impedance matrix for the case of non‐magnetic uniaxial anisotropic media for which the Green's functions are available in closed form. The validity and efficiency of the proposed SIE‐MoM scheme are demonstrated by comparing the results of several case studies against those found in literature and results obtained via commercial numerical codes.

A Simulation study of the output characteristics of freestanding Triboelectric nanogenerators with interdigitated electrodes for self-powered sensing application

Diverse forms of mechanical energy are available in environmental routine activities. These energy forms can be harvested, measured and converted to produce electricity at nanogenerator (NG) and micro-scale levels based on the phenomenon of triboelectrification. These motivate this work to develop a self-powered sensing device to detect and monitor static and dynamic processes associated with mechanical activities. The significance is to study the output characteristics of freestanding mode triboelectric nanogenerator (TENG) with multiple units of metal and dielectric electrodes. The integrated modeling environment of COMSOL Multiphysics software was employed for the simulation study of the proposed TENG. The system output responses considered for analysis includes, open circuit electric potential and short circuit surface charge density. For the open circuit, the electric potential was achieved at maximum value of 10kV, while for short circuit surface charge density, the electric potential was achieved at maximum value of 27 Cm-2. The study results revealed that the input parameter of contact displacement of electrodes is proportional to the output electrical potential of the system. Hence, the efficiency of TENG can be deployed for energy harvesting and sensing of mechanical variables.

Electric field-controlled on-demand surface deformation in liquid crystal polymer networks with topological defects

ABSTRACT Reconfigurable surface morphing control of liquid crystalline polymer (LCP) films at micro or nano scales has emerged as a promising strategy for various applications. Creating reproducible and adjustable platforms enhances their versatility. This study presents a method for controlling stimuli-responsive deformations in liquid crystal polymer network (LCN) films by forming defect arrays using a three-dimensional (3D) electric field generated by crossed electrode systems. The director field of the system can be simulated, enabling investigation of high-temperature deformations through activation force density calculations. To explain the laterally asymmetric deformation of our film, a 3D analysis of the activation force density vector field was essential. Topographical modifications at room temperature are also achieved by incorporating dichroic dye to the monomeric mixture, which promote local monomer diffusion during photopolymerisation. Additionally, by varying the configurations of signal and ground electrodes, different defect structures are generated, leading to distinct deformation patterns at elevated temperatures. Our findings demonstrate that LCN films in this study exhibit programmable nanometre-scale shape deformations, allowing for varied surface patterns from a single setup. This platform significantly enhances the potential of nano- or micro-morphing LCP coatings for advanced applications across multiple fields.

Stable Non-equilibrium Structures in Chiral Nematics under Microfluidic Flow.

Cholesteric liquid crystals (CLCs) are compelling responsive materials with applications in next-generation sensing, imaging, and display technologies. While electric fields and surface treatments have been used to manipulate the molecular organization and, subsequently, the optical properties of CLCs, their response to controlled fluid flow has remained largely unexplored. Here, we investigate the influence of microfluidic flow on the structure of thermotropic CLCs that can exhibit structural coloration. We demonstrate that the shear forces that arise from microfluidic flow align the helical axis of CLCs; alignment is a prerequisite for harnessing the promising photonic properties of CLCs. Moreover, we show that microfluidic flow can generate non-equilibrium structures exhibiting photonic band gaps that are inaccessible in the stationary cholesteric phase. Our findings have implications for the use of CLCs in applications involving flow processing such as additive manufacturing.

Dynamic tunable triple-band terahertz perfect absorber based on graphene metamaterial

This work developed a graphene-based perfect absorber with dynamic tuning capabilities. This absorber consists of a metal substrate, a layer of graphene square rings, a layer of graphene disks, and two layers of SiO2 dielectric sandwiched between them. Simulation results demonstrate absorption peaks at 1.23 THz, 4.2 THz, and 6.38 THz, with respective absorption rates of 99.9 %, 99.8 %, and 98.3 %. By analyzing the distributions of the electric field and surface current at the central frequencies of the three absorption peaks, the excitation mechanism of each absorption peak was discussed. It was found that by adjusting graphene's chemical potential, the absorption spectrum can be actively controlled. Furthermore, the absorber is insensitive to polarization and can sustain the stability of the absorption spectrum within an incident angle range of 0∼35°. This work has the potential to advance the research of multi-band terahertz absorbers, dynamically tunable devices, and other graphene-based photonic devices.

Exploring the inverse line-source scattering problem in dielectric cylinders with deep neural networks

Abstract This study presents a novel approach utilizing deep neural networks to
address the inverse line-source scattering problem in dielectric cylinders. By employing
Multi-layer Perceptron models, we intend to identify the number, positions, and
strengths of hidden internal sources. This is performed by using single-frequency
phased data, from limited measurements of real electric and real magnetic surface fields.
Training data are generated by solving corresponding direct problems, using an exact
solution representation. Through extended numerical experiments, we demonstrate
the efficiency of our approach, including scenarios involving noise, reduced sample
sizes, and fewer measurements. Additionally, we examine the empirical scaling laws
governing model performance and conduct a local analysis to explore how our neural
networks handle the inherent ill-posedness of the considered inverse problems.

Robust Multi-Band DNG metamaterial absorber for GPS (L1), ISM, and 5G application with Enhanced polarization and angle stability

This research introduces a triple-band metamaterial absorber characterized by insensitivity to both polarization and incident angles. The structure includes square ring resonators on the upper side and a continuous metal ground on the lower side, separated by an FR4 substrate. At the lowest operating frequency, the unit cell’s thickness, and length measure 0.0128λ and 0.156λ, respectively. Under normal incidence, the proposed absorber demonstrates three clear absorption peaks at 1.56, 2.43, and 3.36 GHz, achieving absorption rates of 98 %, 99 %, and 97 %, respectively. The absorption response exhibits variation with incident angles up to 70° for both TM and TE polarizations due to its high-level symmetry. This configuration attains negative permittivity and permeability suitable for operational frequencies in the L-band and S-band. The study examines the electric field, impedance, and surface current to provide additional evidence for the absorption analysis. A validated RLC circuit equivalent to the proposed structure has been confirmed using Advanced Design System (ADS). The results indicate a slight deviation, especially at frequencies beyond the resonance frequencies. The structure underwent fabrication and testing in an anechoic chamber, revealing a strong correlation between the simulated and measured results. The suggested absorber holds promise for ISM applications, radar systems, sensing technologies, and energy harvesting systems.

Circular-ring tied arc loaded excellent metamaterial absorber for EMI shielding of Wi-Fi signal and impurity sensing of cooking oil

This paper demonstrates a unique symmetric structure excellent metamaterial absorber (MMA) loaded with circular-ring tied arcs. The FR4 substrate-based MMA can accomplish 98.88 % and 99.81 % absorption maximums at the Wi-Fi and 5G frequencies of 2.4 GHz and 5.0 GHz respectively. The unit cell dimension of 0.16λ0×0.16λ0×0.0128λ0 is considered where the wavelength, λ0 is calculated at 2.4 GHz. The performance of the absorber is analyzed through the electric field, magnetic field, surface current, and effective parameters. The dimensions are optimized through the parametric analysis of the developed model in CST software. The model exhibits stability up to 60° for Transverse electric and magnetic polarizations. During electromagnetic interference (EMI) shielding demonstration, it can achieve a high shielding effectiveness (SE) of 54.34 dB at 2.4 GHz and 77.96 dB at 5.0 GHz. For sensing operation, it can attain a quality factor (Q-factor) of 25.61, a sensitivity of 3.30 %, and a figure of merit (FoM) of 84.51. The prototype measurements of the MMA for EMI shielding and impurity sensing of oil samples have a strong correlation with the simulation performance. Because of the high SE, Q-factor, sensitivity, and FoM, the developed MMA can be a competitive candidate in EMI shielding and oil impurity sensing applications.

Dispersion compensation design of high-density stacking RFSS absorbers for wideband applications

Abstract A dispersion compensation design absorber realized by high-density stacking resistive frequency selective surface (RFSS) is proposed for wideband applications. Firstly, the quantitative relationship between the equivalent impedance of RFSS and the permittivity of the effective media is constructed with the help of the transmission matrix method. The dispersion regulation of permittivity is achieved by changing the pattern and the square resistance of RFSS. In terms of absorber design, a uniform absorber with dispersion manipulation is developed as a precursor absorber. The uniform absorber has an absorption performance better than −8.5 dB above 2 GHz at normal incidence. The loss mechanism is analyzed in detail by electric field distribution and surface power loss density distribution, indicating that the uniform design cannot achieve thickness saving when extending to low frequency. Therefore, a dispersion compensation design absorber is proposed to extend −10 dB bandwidth to 1.64–28.8 GHz. Experiment results agree well with the simulation results, validating the analytic methods and design principles.

Terahertz tunable quasi-bound state in the continuum metasurface with high sensitivity based on Dirac semimetal

We have proposed a novel tunable terahertz (THz) quasi-bound states in the continuum (BIC) metasurface based on Dirac semimetal (DS). By modifying the structural parameters of the DS resonator and disrupting the C4 symmetry to induce perturbations, we achieve the conversion of BIC to quasi-BIC with a high Q-factor, reaching up to 1291.3. Moreover, we conducted a systematic analysis of the electric field distribution and surface current density for both symmetric and asymmetric configurations to elucidate the formation mechanism of the quasi-BIC. Furthermore, by varying the Fermi energy of the DS within the range of 0.1–0.2eV, we achieved continuously tunable operation with the operating frequency ranging from 1.179 to 1.248 THz and the transmission from 21.18% to 96.87%. Most notably, we investigated the sensing performance of the device, finding that its refractive index sensitivity and figure of merit (FOM) are 0.301 THz/RIU and 143.3 RIU−1, respectively, highlighting its potential for high-sensitivity applications, particularly in material detection and biomedical diagnostics.

Control and Regulation of Au Hillocks Growth by the Electrical Field and their Metastable Dynamics in Ambient Atmosphere

Abstract With the rapid development of electronic engineering and nanotechnology, the electrical field-induced surface migration plays an increasingly important role in the fields of materials science. By comparing the changes in the surface migration behavior of gold nanogap electrodes under different electric field parameters, we reveal the kinetic processes and influencing factors of electric field-induced surface migration. Under the condition of only 1 pA current limit, under the continuous electric field, the hillcok only appears in the anode and gradually evolve into multiple peaks when rises to some extent. By establishing a finite element model of the nanogap, we find the hillock grows under the field strength gradient. Then hillock growth is biregulated by applying a positive or negative voltage to the drain end of the gap device. Located in the normal temperature atmosphere, the morphology will degenerate, and this feature is opposite to the hillock generated by electromigration.

Triple-frequency terahertz modulator based on electronically controllable metamaterial from the coupling effect

This paper proposes a triple-frequency terahertz amplitude modulator that utilizes an I-shaped strip and four U-shaped metal patches within a common metal-substrate configuration. The top metal layer consists of an I-shaped strip and four U-shaped metal patches, while the bottom substrate layer is made of polyimide. Amplitude modulation is achieved through adjusting the plasma frequency of the high-electron-mobility transistors, resulting in a modulation depth of nearly 93% at resonance frequencies of 0.26 and 0.49 THz. At 0.6 THz, the modulation depth reaches 65%, demonstrating excellent performance. Resonance frequencies are determined by electric field and surface current distribution. The triple-frequency terahertz amplitude modulator is applicable in various fields, including terahertz communications and imaging.

An ultra broadband metamaterial absorber based on metal-dielectric-metal technology for THz spectrum

This paper introduces a novel ultra-broadband Metamaterial Absorber (UBMA) demonstrating significant absorption capabilities across a wide terahertz frequency range from 2.42 THz to 6.11 THz. The 3.7 THz bandwidth represents 87% of the central frequency. The proposed UBMA comprises three layers: a star-shaped metal patch on top, a dielectric substrate in the middle, and a metallic ground plane below. Simulations using CST Microwave Studio software reveal that the design achieves high absorption at five distinct frequencies: 2.47, 3.45, 4.89, 6.01, and 6.87 THz, with absorption rates of 99% for the first four peaks and 90% for the fifth peak. The study of electric field and surface current distribution provides insights into the absorption mechanism. While the UBMA exhibits polarization-independent performance, its angular response shows some sensitivity to the incident angle, especially beyond 30° Despite this, the absorber maintains over 70% absorptivity up to a 45° incidence angle for both TE and TM polarizations within specific frequency ranges. The simple structure combined with high absorption efficiency makes the UBMA suitable for THz imaging, detection, and stealth applications, although its angular sensitivity must be considered for certain applications.