Fringing Field Effect Research Articles

Augmentation of the stable static travel range of electrostatically actuated slender nano-cantilevers by accounting for the influence of the van der Waals force

The van der Waals (vdW) force, along with the electrostatic force and the first-order fringing field effect, act on the electrostatically actuated nano-cantilever (EANC) when the gap between the deformable electrode and the stationary electrode is less than 20 nanometres. Because of the vdW force, the EANC can undergo a pull-in phenomenon even without the electrostatic force when the nano-cantilever length exceeds its detachment length. The vdW force also results in a significant reduction in static pull-in instability parameters of the slender EANC compared to corresponding parameters obtained when this force is absent. This paper aims to augment the stable static travel range (i.e., the pull-in displacement) of the aforementioned EANC having a length close to its detachment length by varying the beam width. The beam width is assumed to vary in linear and parabolic manners and is controlled using a width variation parameter in each case. The governing equation of the Bernoulli-Euler beam theory and the Galerkin’s technique are utilised to obtain the weighted residual statement (GWRS). The GWRS is utilised to obtain static pull-in instability parameters of referential prismatic and variable-width EANCs. Pull-in instability parameters of variable-width EANCs, for various values of width variation parameters and the initial gap between electrodes, have been obtained. The aforementioned results have been validated with corresponding results obtained by three-dimensional finite element simulations performed using COMSOL Multiphysics®. Compared to the referential prismatic EANC, a significant augmentation in the pull-in displacement of the variable-width EANC has been obtained.

All region analytical modeling of 2-D transition metal dichalcogenide FET by considering effect of fringing field and region-wise mobility

In this paper, for the first time an analytical all region model of Transition metal dichalcogenide based FET has been developed to represent the current–voltage characteristics of the device in ultra-short channel regime. Starting from Gauss’s law, Poisson’s equation is formulated and short channel subthreshold current model is developed subsequently. In order to include fringing field effect, the gaussian box is considered for top and bottom oxides along with channel. Next, Velocity saturation model is developed by considering mobile charges due to top-bottom gates and region-wise field dependent mobility in the channel utilizing the drift diffusion approach. Both the models are then unified by finding the natural points of transition from one model to other. The intraband source to drain tunneling has also been incorporated to develop generalized 2-D material based FET model. Veracity of the model has been verified with NEGF simulations for different device parameters and excellent congruence is observed. The effect of the interface trap charge density has also been included in the model and its effects on the transfer characteristics are investigated. • Analytical modeling of I-V characteristics for TMD materials applicable for all channel lengths. • Validation of model with atomistic simulator data for Sub 10 nm channel length. • Effects of double gate and fringing field have been included. • Source to drain tunneling has been included to increase model applicability for any 2D materials.

A detailed investigation of dielectric-modulated dual-gate TMD FET based label-free biosensor via analytical modelling

In this work, an analytical model is developed for DM-DG-TMD-FET- based Biosensor including Fringing-field effects. The Analytical model has been developed for two different Device structures, namely Device structure-1 (without a gate above the nano-cavity) and Device structure-2 (with a gate above the nano-cavity) based on modulation of the dielectric constant of biomolecules in the nano-cavity region. The proposed model has been validated against both numerical quantum simulation results with the help of a few fitting parameters and it also agrees with the 2-dimensional numeric simulator SILVACO TCAD used in this work. The presence/absence of biomolecules has been detected by the metric of threshold voltage sensitivity S_{Vth} and drain current I_{d} for the neutral as well as charged biomolecules. Sensitivities of partially filled nano-cavities arising out of steric hindrance in both the biosensors are compared. Optimization of device dimensions has also been included in this work to enhance the sensitivity of the biosensors. It has been witnessed that the sensitivity of the proposed biosensor is sim 100% higher in Device structure-1 for neutral biomolecules with dielectric constant kappa = 12, when compared to Device structure-2 for fully filled cavities. Whereas for the charged biomolecules, Device structure-1 shows sim 50% enhanced sensitivity than Device structure-2 for N_{f}=-1times 10^{-12}text{C}/text{cm}^2. Device structure-1 demonstrates sim120% higher sensitivity than Device structure-2 with partially filled cavities (i.e. 66% filled cavity). Finally, benchmarking of the proposed biosensor is presented with contemporary, state-of-the-art biosensors and it is highlighted that MoS_{2} FET-based biosensor emerges with a superior sensitivity of S_{Vth} = 0.81 V for kappa = 12.

Study on the fringe field effect of quadrupoles for CSNS MEBT

Study on the fringe field effect of quadrupoles for CSNS MEBT

Non-ohmic electrical fringe field selective to biofilm suitable for addressing biofouling in wastewater treatment

The non-ohmic electrical fringe field has been shown to be a viable approach for addressing biofouling in wastewater treatment. Existing attached growth systems require periodic mechanical- or chemical-based maintenance or part replacement to regulate excessive biofilm formation. The proposed electrical approach uses a non-ohmic fringe field at a low voltage of 10 V and a low frequency of 100 kHz, where bacterial biofilm growth is noticeably reduced. The fringe field was generated by insulated interdigitated electrodes embedded below the surface on which the biofilm grew. Electric field simulation showed field strength of 15.2 and 12.3 V/cm at 0.05 and 1 mm from the surface, respectively, which are sufficient to reduce biofilm growth. As the biofilm grows, the fringe field passing through it becomes denser (hence, higher field strength) owing to the difference in relative permittivity. It selectively targeted biofilms in water. The optical density measurements showed that the presence of fringe field was able to reduce the biofilm by ∼10.1 % as compared to the control. Adenosine triphosphate measurements suggested that the effect of fringe field on bacterial viability was even more pronounced at ∼20.6 % reduction. This is an efficient approach with no moving parts suitable for uninterrupted biofilm growth regulation in wastewater treatment.

Nonlinear damping in micromachined bridge resonators

This study presents a thorough theoretical and experimental investigation on the nonlinear damping of in-plane micromachined electromechanical resonators. More specifically, experiments are conducted on an electrically actuated bridge resonator, and the primary resonance response of the system is obtained at various AC and DC voltages. A nonlinear theoretical model is developed using the Euler–Bernoulli beam theory while accounting for the geometric, electrostatic (including fringing field effect), and damping nonlinearities. Two damping models are considered in the theoretical model: the Kelvin–Voigt model, which for this system is a nonlinear damping model due to the presence of geometric nonlinearities. The second damping model consists of linear, quadratic, and cubic damping terms. A high-dimensional discretisation is performed, and the nonlinear dynamics of the resonator are examined in detail in the primary resonance regime by constructing the frequency response diagrams at various AC and DC voltages. Thorough comparisons are conducted between the experimental data and the theoretical results for different damping conditions. It is shown that the microresonator displays strong nonlinear damping. Detailed calibration procedures for the nonlinear damping models are proposed, and the advantages and disadvantages of each nonlinear damping model are discussed.

40.3: Fast Fringe‐field‐effect Free Continuous 2.25π Phase Modulation Based on Non‐linear Kerr Effect of Vertical Aligned Deformed Helix Ferroelectric Liquid Crystal

40.3: Fast Fringe‐field‐effect Free Continuous 2.25π Phase Modulation Based on Non‐linear Kerr Effect of Vertical Aligned Deformed Helix Ferroelectric Liquid Crystal

1.3: Active‐matrix Addressed High Brightness and Ultra‐high PPI Field‐Sequential‐Color Display based on Deformed Helix Ferroelectric Liquid Crystal for VR/AR

Barriers exits regarding increasing brightness and pixel density for various display technologies, be it, LCD, LED and OLED. In this paper, we proposed a defect‐free high‐contrast fast (~100μ) active‐matrix addressed DHFLC with a theoretical 11500 PPI due to its nature of no fringe field effect (FFE) and high capacitance, shedding a light on the barriers. For the realization, the no‐storage‐capacitor AM‐DHFLC display device is fabricated as preliminary demo with both optimizations in the DHFLC alignment and pixel design. Innovatively, the no‐storage‐capacitor characteristic, which is impossible for NLC, not only rockets efficiency and aperture ratio from 57% to 83% with high brightness, but also reveals the potential in reducing the pixel size for higher resolution. Moreover, fast response around 100μs at 360 Hz for FSC display and no‐FFE strengthen the promising potential of DHFLC in various modern display technologies, be it VR/AR, high PPI display, micro display, and high‐resolution hologram.

3.3: Fast Continuous >2π Phase Modulation without Fringe Field Effect based on Kerr Effect of Vertical Aligned Ferroelectric Liquid Crystal

3.3: Fast Continuous >2π Phase Modulation without Fringe Field Effect based on Kerr Effect of Vertical Aligned Ferroelectric Liquid Crystal

Impedance Analysis of Chitin Nanofibers Integrated Bulk Acoustic Wave Humidity Sensor with Asymmetric Electrode Configuration.

This paper fabricated a high-performance chitin nanofibers (ChNFs)-integrated bulk acoustic wave (BAW) humidity sensor with an asymmetric electrode configuration. The ChNFs were successfully prepared from crab shells and used as moisture-sensitive materials to compare the performance of quartz crystal microbalance (QCM) humidity sensors with symmetric and asymmetric electrode structures. The QCM humidity sensor with a smaller electrode area exhibited high sensitivity of 58.84 Hz/%RH, competitive response/recovery time of 30/3.5 s, and low humidity hysteresis of 2.5% RH. However, it is necessary to choose a suitable electrode diameter to balance the stability and sensitivity because the impedance analysis result showed that the reduction of the electrode diameter leads to a sharp decrease in the Q value (stability). Next, the possible humidity-sensitive mechanism of the ChNFs-integrated asymmetric n-m electrode QCM humidity sensor was discussed in detail. Finally, the reasons for the highest sensitivity of the asymmetric n-m electrode QCM humidity sensors having a smaller electrode diameter were analyzed in detail in terms of both mass sensitivity and fringing field effect. This work not only demonstrates that the chitin nanofiber is an excellent potential material for moisture detection, but also provides a new perspective for designing high-performance QCM humidity sensors.

Critical Importance of Nonuniform Polarization and Fringe Field Effects for Scaled Ferroelectric FinFET Memory

The ferroelectric field-effect transistor (FEFET) is an emerging nonvolatile memory technology that can offer ultra-scalability, fast operation, and reduced power consumption. However, a limited understanding of FEFET physics poses challenges for optimum device design. In this article, we provide physical insights into the operation of FinFET-based FEFETs (FEFinFETs) using a phase-field framework built on time-dependent Landau–Ginzburg (TDGL) thermodynamic theory. We exploit the source–drain fringing field to stabilize a monodomain configuration in the OFF state of short channel FEFinFETs. Based on recent experiments, we first analyze the switching dynamics of FEFinFETs with low remnant polarization ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{r}$ </tex-math></inline-formula> ) and high coercive field ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{c}$ </tex-math></inline-formula> ) hafnium zirconium oxide (HZO) FE. We find that the switching in these FEFinFETs occurs via domain nucleation and growth from the gate metal edges at the source–drain spacers. We also show that a non-zero drain bias can be used for dynamically modulating the memory window (MW) of FEFinFET to lower its power consumption. Furthermore, we find the spacer permittivity to be a crucial design parameter to control the MW and show that a lower spacer permittivity can significantly increase the MW. Finally, we show that the commonly held idea that a large <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{r}$ </tex-math></inline-formula> leads to a large MW is not always valid. For a large <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{r}$ </tex-math></inline-formula> , the formation of multiple domains in the FE layer can lead to a significant reduction in the MW. In addition, these devices can suffer from low write endurance due to exposure of the interfacial oxide layer to high electric fields.

Coupling Design of Combined Function Bending Magnet and High Current Electron Beam for 100 kW Irradiation Accelerator

RF system is one of the key components of a 2 GeV, 6 MW high power fixed field alternating gradient (FFAG) accelerator being designed at China Institute of Atomic Energy (CIAE). In order to verify the design principle and the engineering feasibility, a scaled-down RF cavity is under construction, which can also be used as the main accelerating cavity for a 100 kW electron irradiation accelerator. By the deflections of several 180 degrees bending magnets, the electrons emitted from the electron gun can pass the cavity for multiple times. Due to the limited length of the cavity, the deflection radius should be as small as possible to ensure more acceleration times and consequently higher beam power, which will make the fringe field effect of the bending magnet be a problem. In addition, the bending magnet should provide beam focusing in both the radial and axial directions of the beam and keep the beam envelope stable during the whole acceleration process. Based on the above reasons, the parameters of the combined function bending magnet, such as the pole face rotations (Liu, 1994), magnetic field gradient and shielding distance, have a great influence on the beam dynamics behavior in the accelerator, which bring great difficulty to the design of the combined function bending magnet. In this paper, the coupling design of the bending magnet with focusing function and the high intensity electron beam for this 100 kW irradiation accelerator will be illustrated in detail.

Effect of external electric potential on the mechanical resonance of MEMS cantilever resonator

This work presents an analytical model to predict the natural frequency of electrostatically actuated micromachined cantilever beam under the application of DC voltage. The analytical modelling uses an energy based method with a sinusoidal vibration assumption. The electric field between the cantilever electrodes is assumed to be vertical and fringing field effects are neglected. The behaviour of natural frequency and a closed-form expression for pull-in voltage are evaluated. The electrostatic spring softening effect of DC bias on the resonant natural frequency is studied in particular. Results are compared with simulation in ANSYS.

63‐1: Distinguished Student Paper: Microsecond High‐contrast Continuous 2.25π Phase Modulation Based on Non‐linear Kerr Effect of VADHFLC

Here we disclose a fast (ON time ~50μs and OFF time‐25μs at 55°C), high‐contrast, continuous phase modulator without fringe field effect (FFE). The phase modulator using the Kerr effect of vertical aligned deformed helix ferroelectric liquid crystal (VADHFLC). Specifically, FFE is a long‐term problem for nematic liquid crystal (NLC). In this article, we are disclosing, for the 1st‐time found, that no FFE exists for VADHFLC, even for phase modulator with 1μm pixel pitch, which is an attractive feature for ultra‐high‐resolution display and photonic applications. Moreover, the Kerr constant is 88 nm/V2, and the contrast ratio is larger than 1000:1. It is a promising candidate for high‐PPI AR/VR displays, wavelength selective switch (WSS), hologram, adaptive optics, and LiDARs.

11‐2: Student Paper: High Brightness and Ultra‐High PPI Field‐Sequential‐Color (FSC) Display Based on Deformed Helix Ferroelectric Liquid Crystal for VR/AR

Different display‐based technologies like LCD, OLED and LED, all meet barriers in increasing brightness and pixel density. In this paper, a defect‐free high‐contrast fast (~100 μs) active‐matrix addressed DHFLC is proposed with a theoretical 11500 PPI due to its nature of no fringe field effect (FFE) and high capacitance, shedding a light on the barriers. For the realization, the no‐storage‐capacitor AM‐DHFLC display device is fabricated as a preliminary demo with both optimizations in the DHFLC alignment and pixel design. Innovatively, the no‐storage‐capacitor characteristic, which is impossible for NLC, not only rockets efficiency and aperture ratio from 57 % to 83 % with high brightness, but also reveals the potential in reducing the pixel size for higher resolution. Moreover, a fast response around 100 μs at 360 Hz for FSC display and no‐FFE strengthens the promising potential of DHFLC in various modern display technologies, be it VR/AR, high PPI display, microdisplay, and high‐resolution hologram.

Microsecond high‐contrast continuous 2.25π phase modulation based on non‐linear Kerr effect of vertically aligned deformed helix ferroelectric liquid crystal

AbstractHere we disclose a fast (ON time ∼50 μs and OFF time ∼25 μs at 55 ), high‐contrast, continuous phase modulator without fringe field effect (FFE). The phase modulator uses the Kerr effect of vertically aligned deformed helix ferroelectric liquid crystals (VADHFLCs). Specifically, FFE is a long‐term problem for nematic liquid crystals (NLCs). In this article, we are disclosing, for the first‐time found, that no FFE exists for VADHFLCs, even for phase modulator with 1‐μm pixel pitch. It is an attractive feature for ultra‐high‐resolution display and photonic applications. Moreover, the Kerr constant is 88 , and the contrast ratio is larger than 1000:1. It is a promising candidate for high‐PPI augmented reality (AR)/virtual reality (VR) displays, wavelength selective switch (WSS), hologram, adaptive optics, and LiDARs.

Polarimetric analysis of cross-talk phenomena induced by the pixelation in PA-LCoS devices

Liquid crystal on silicon (LCoS) microdisplays are an element commonly found in advanced photonic applications. Phase-only modulation and spatial light modulators (SLMs) use parallel-aligned LCoS (PA-LCoS) microdisplays due to their large resolution and small pixel size. However, the crosstalk between neighbouring pixels induces several phenomena, i.e. the smoothing of the electric field in the interpixel region known as fringing fields, out-of-plane reorientation of the liquid crystal director, and diffraction effects due to the finite pixel grid pattern. These effects degrade the performance in SLM applications. Therefore, a rigorous numerical analysis is carried out based on a full 3D model that estimates the LC director distribution of the PA-LCoS microdisplay through uniform applied voltages. Once the LC director distribution is known, a numerical finite-difference scheme simulates light propagation across the structure. Here, the impact of crosstalk is analysed from the polarimetric point of view for different pixel and interpixel sizes. It has been found that the finite-patterned pixel scheme induces the phenomena previously addressed, degrading the responses of the Stokes vector components S0, and S1 and also the degree of polarization (DOP). Furthermore, the impact over these parameters is generally inversely proportional to the fill factor. To isolate the influence of diffraction, out-of-plane, and fringing fields effects is challenging since all phenomena are mixed in both time and space, however we have found some useful trends.

On the relationships between resolution, dimensionless stability, pseudopotential well depth, acceptance, and transmission in mass filters.

The relationships between resolution, stability, pseudopotential well depth, acceptance aperture, and transmission for sinusoidal quadrupole mass filters are examined graphically and mathematically. Simple linear or power relationships are revealed. Comparison of these quantities plotted against resolving power show that the pseudopotential well depth correlates well with the mass filter transmission. Pseudopotential well depth is directly proportional to the product of dimensionless stability well depth and the AC voltage. This relationship extends to all quadrupoles regardless of operational zone because it is rooted in stability. Ion transmission and sensitivity scale directly with the pseudopotential well depth. Resolving power and pseudopotential well depth increase when operating in higher stability zones for all types of mass filters. Unfortunately, for fixed frequency sine wave mass filters, the increased resolving power and pseudopotential well depth are accompanied by a significant reduction of the mass range and increased in fringe field effects. For these reasons, sine mass filter operation in higher stability zones has been reported but not commercially produced. In contrast, for rectangular wave mass filter operation, there is no mass range limitation in any stability zone. The fringe field does not increase because the AC voltage is constant and does not change within a single stability zone or between them. A DC voltage is also unnecessary to access any zone. The high resolution and sensitivity of rectangular wave mass filters that can be gained by operation in higher stability zones without mass limit and limited fringe field restrictions suggest a bright and expansive future for this technology.

Analytical Modeling of Short-Channel TMD TFET Considering Effect of Fringing Field and 2-D Junctions Depletion Regions

An analytical drain current model is developed for a short-channel, dual-gate, monolayer 2-D transition metal dichalcogenide (TMD), lateral tunnel field-effect transistor (TFET) by considering 2-D <inline-formula> <tex-math notation="LaTeX">${p}^{+}-{n}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">${n}-{n}^{+}$ </tex-math></inline-formula> junction at source&#x2013;channel and channel&#x2013;drain junction, respectively. This work includes the effect of both front- and back-gate dielectric fringing field effects and 2-D source and drain depletion charges. A unified piecewise surface potential model is developed by capturing the fringing field effects in the channel and 2-D junction behavior at the source&#x2013;channel and channel&#x2013;drain junction by ensuring continuity of electric field at the junction regions. A tangent-line approximation method is employed for accurate numerical evaluation of the tunneling current. The proposed model is validated with simulation results obtained using nonequilibrium Green&#x2019;s function (NEGF)-based simulator for different 2-D layered materials and a close agreement is observed. The veracity of the proposed model is tested with data in reported studies for different bias conditions and excellent matching is observed. The applicability of the model is demonstrated for any 2-D layered material-based TFET from ultrashort channel to a channel length of 50 nm. The proposed model will be extremely useful for further exploration of 2-D TMD material TFET-based very large-scale integration (VLSI) circuits.

Simple method to evaluate the pixel crosstalk caused by fringing field effect in liquid-crystal spatial light modulators

In this work we provide a simple experimental method to measure and evaluate the pixel crosstalk in phase-only liquid-crystal displays caused by the fringing field effect. The technique is a reverse engineering method that does not require information about the microscopic physical parameters of the liquid-crystal material or details of the fabrication and electronics of the display. Instead, it is based on the overall effect on the diffraction efficiency of displayed binary phase gratings as a function of the addressed gray level. We show how the efficiency of the zero (DC) and first diffraction orders provides valuable information enough to identify and quantify the pixel crosstalk. The technique is demonstrated with a modern phase-only liquid-crystal on silicon (LCOS) spatial light modulator (SLM), illustrating the limitations that this effect imposes to the spatial resolution of the device and providing quantitative measurement of the impact on the diffraction efficiency.