Range Of Electric Fields Research Articles

Water-Borne Fluorinated Polyimide Dielectric for Large-Area IGZO Transistors and Logic Gates.

Thin-film transistors offer excellent and uniform electrical properties over large areas, making them a promising option for various future electronic devices. Polyimide dielectrics are already widely used in various electronic devices because of their exceptional dielectric properties, thermal stability, and desirable mechanical flexibility, which make them suitable for harsh environments. However, the current research on polyimide dielectric materials has certain limitations, such as the use of toxic solvents, high-temperature processes, and deficient coating properties. Herein, we introduce an aromatic polyimide dielectric, which exhibits excellent electrical properties even when processed at a low temperature of 250 °C using environmentally friendly water-based "one-step" polymerization. Despite its thin thickness of <200 nm, the water-borne fluorinated polyimide dielectric material demonstrates stable insulating properties over a wide range of electric fields and achieves a high breakdown voltage of over 4.5 MV cm-1. Furthermore, we successfully achieved a large-area coating of uniform dielectric layers with no pinholes using only water as a solvent and a simple solution process without any additional processing steps. These results demonstrate that the water-borne polyimide gated indium-gallium-zinc oxide transistor exhibits excellent and stable device performance. Moreover, we used the transistor to successfully demonstrate various logic gates (NOT, NAND, and NOR). Overall, this study provides guidelines for the eco-friendly and sustainable use of water-borne polyimide dielectric materials with high electrical performance and large-processing window advantages.

The dynamics of pinned charge density wave in NbSe3 nanoribbons revealed by noise spectroscopy

Abstract Systematic nonlinear transport and broadband noise (BBN) measurements are performed on single nanoribbon devices of the charge density wave (CDW) conductor NbSe$_{3}$ over a wide range of excitation levels and temperatures. The nonlinear voltage-current characteristics elucidate the depinning process of the two CDWs and the temperature dependence of their threshold electric fields. Within the temperature and electric field range where the CDW is anticipated to be entirely pinned by residual impurities, a non-monotonic behavior in the noise magnitude versus electric field is observed. This phenomenon is attributed to the proliferation of thermally activated phase slip events, enhanced by the size effect in nanodevices. The idea is corroborated by the observation of a smeared activated behavior described by the Dutta-Horn relation. Certain aspects of the temperature dependence of the noise magnitude deviate from a simple activated behavior, suggesting a multifaceted origin of the resistance fluctuations in CDW systems at the nanometer scale. These findings provide valuable insights into the dynamics of CDW in nanodevices.

Diffusion and mobility measurements for propane gas with a nanodosimetric detector

For the operation of nanodosimetric detectors with propane gas, it is essential to know the gas properties at room temperature, such as drift velocity, ion mobility, longitudinal and transversal diffusion coefficients. For propane gas there is only limited experimental data available for the ion mobility and transverse diffusion coefficients. In this work, the drift velocities and ion mobilities for propane were obtained over the reduced electric field range E/N from 24 to 212 Td (1 Td = 10−17 Vcm2) based on arrival time measurements. The reduced ion mobility K0 for propane was determined to be (0.71±0.09) cm2/Vs. The longitudinal diffusion coefficients were determined from the widths of the experimental arrival time spectra and found to be NDL = (3.7 ± 0.5)⋅1019 1/ms in the low field limit below 30 Td.The results presented in this work extend the range of available experimental data for propane, as well as introduce first experimental measurements of the longitudinal diffusion coefficient of propane.

Enhanced energy storage properties of BaTiO3 ceramics: Effect of doping Bi(Mg0.25Zn0.25Ti0.5)O3 on microstructure, dielectric and ferroelectric properties

(1-x) BaTiO3 – x Bi(Mg0.25Zn0.25Ti0.5)O3 (x = 0.00, 0.06, 0.12, 0.20,molar ratio) ceramics were prepared by solid sintering method. The effects of Bi(Mg0.25Zn0.25Ti0.5)O3 (BMZT) doping on microstructure, dielectric, ferroelectric and energy storage properties of BaTiO3 (BTO) were studied. With BMZT addition, the sintering temperature gradually decreases, the grain size reaches a minimum at x = 0.12 and the phase structure changes from tetragonal to cubic. And dielectric properties changed from temperature-dependent to temperature-insensitive. Additionally, higher cubic phase content induced slim polarization and electric field (P-E) loop and low remnant polarization (Pr). Therefore, 0.88 BaTiO3 - 0.12 Bi(Mg0.25Zn0.25Ti0.5)O3 ceramics achieved recoverable energy storage density (Wrec) of 702.7 mJ/cm3 and high energy efficiency of 87.3 % under electric field of 93 kV/cm. It exhibited optimum properties, including a minimum grain size (0.620 μm), superior dielectric properties (εr = 1811.3, tanδ = 0.0552 at 1150 °C), a high maximum polarization strength (14.3 μC/cm2), and the maximum dielectric breakdown strength (93 kV/cm), as identified in the present study. It simultaneously maintains high energy storage density and efficiency over a wide electric field range and large temperature range (room temperature - 90 °C). Thus (1-x) BaTiO3 – x Bi(Mg0.25Zn0.25Ti0.5)O3 ceramics are a promising material for energy storage applications.

Stable energy storage performance of introduced PI-PESU dielectric composite serving at the high electric and thermal fields with the designed layer structure

Excellent energy storage performance of dielectric capacitor is critical in modern electronic devices and power systems. However, the key component of dielectric composite may fail to function properly under severe service conditions, such as elevated temperature and great applied electric field. Here, the linear dielectrics of PI and PESU with high glass transition temperature (Tg) were proposed to improve the energy storage performance of composite, which hold the weakened carrier migration. The large band-gap of PESU and tight molecular chain of PI are beneficial for reducing leakage current density of composite, enhancing inter-molecular stability over a wide temperature and electric field range. Finally, the energy storage performance is improved by constructing a multi-layer structure with alternating outer layers. For instance, the discharge energy density (Ue) of 0.4PI-0.6PESU composite reaches 6.38 J/cm3 at 700 kV/mm and 80 °C. Significantly, the Ue of multi-layer 2/1/PVDF/1/2 composite is increased by 92.36 % at 80 °C and 400 kV/mm (from 2.88 J/cm3 to 5.54 J/cm3), and the efficiency (η) of it keeps at 68.5 %. Meanwhile, it owns a good cycle stability after 50,000 cycles with η > 90 %. This work provides a new direction of developing dielectric composite serving in severe service conditions for capacitors.

The impact of electric field strength on the accuracy of boron dopant quantification in silicon using atom probe tomography

This study investigates the impact of the surface electric field on the quantification accuracy of boron (B) implanted silicon (Si) using atom probe tomography (APT). The Si Charge-State Ratio (CSR(Si) = Si2+/Si+) was used as an indirect measure of the average apex electric field during analysis. For a range of electric fields, the accuracy of the total implanted dose and the depth profile shape determined by APT was evaluated against the National Institute of Standards and Technology Standard Reference Material 2137. The radial (non-)uniformity of the detected B was also examined. At a higher surface electric field (i.e., a greater CSR(Si)), the determined B dose converges on the certified dose. Additionally, the depth profile shape tends towards that derived by secondary ion mass spectrometry. This improvement coincides with a more uniform radial B distribution, evidenced by desorption maps. In contrast, for lower surface electric fields (i.e., a lower CSR(Si)), the B dose is significantly underestimated, and the depth profile is artificially stretched. The desorption maps also indicate a highly inhomogeneous B emission localized around the center of the detector, which is believed to be an artifact of B surface migration on the tip of the sample. For the purposes of routine investigations of semiconductor devices using APT, these results illustrate the potential origin of quantification artifacts and their severity at different operating conditions, thus providing pathways towards best practices for accurate and repeatable measurements.

Impact of Pulsed Electric Field Ablation on His Bundle Conduction: A Preclinical Canine Study.

BACKGROUND Pulsed field ablation (PFA), as a non-thermal ablation modality, has received increasing attention. The aim of this study was to evaluate the effect of PFA upon His bundle via its implementation with different voltages on the maximum His bundle potential in canines, providing scientific basis for clinical application. MATERIAL AND METHODS Pulsed electrical field energy was delivered from a ablation catheter to the maximum His potential of 7 dogs, followed by a series of electrogram and histology assessments. RESULTS The baseline AH and HV intervals were 55.3±3.7 ms (range, 53.0-59.0 ms), and 34.9±1.3 ms (range, 34.0-36.0 ms), respectively, which were elevated to 65.0±5.4 ms (range, 59.0-70.0 ms) and 35.7±2.7 ms (range, 34.0-37.0 ms) after PFA. Before ablation and immediately after the recovery of third-degree AVB, the AH interval was prolonged (P<0.05) while the HV interval remained unchanged (P>0.05). After ablation, all 7 canines experienced transient third-degree AVB, with a voltage-dependent duration. Masson staining results revealed no apparent damage in His bundle cells. CONCLUSIONS Within a certain voltage range of pulse electric field, ablation of the maximum His potential in canines can result in transient third-degree AVB, providing a new route for guiding safe ablation of para-Hisian arrhythmia.

Abundant electric-field tunable symmetry-broken states in twisted monolayer-bilayer graphene

Electron-electron correlations can lift the high degeneracies in strong correlated systems, resulting in various symmetry-broken states. Twisted monolayer-bilayer graphene (tMBG) is an especially rich system due to its low crystalline symmetry. Here, we report abundant electric-field tunable symmetry-broken states in tMBG. The ground state at half filling of the conduction flat band is spin- and valley-polarization dominated under positive and negative electric field, respectively, consistent with our theoretical calculations. In addition, we find a symmetry-broken Chern insulator emanating from 1.5 electrons per moiré unit with C = 3 emerges at high magnetic field in a negative electric field range. The C = 3 suggests that one and a half flavor-polarized Chern 2 bands within the same valley are filled, consistent with the valley-polarization-dominated half-filling state under negative electric field, while the fractional filling stems from a density-wave state held by enlarged unit cells containing two moiré units.

Bragg diffraction of higher orders on oblique helicoidal liquid crystal structures

ABSTRACT For the oblique helicoidal (ChOH) structure of the chiral twist-bend nematic-forming mixture of CB7CB/CB6OCB/5CB doped by light-sensitive chiral compound based on azo-fragment, at oblique incidence of light two consequent states of Bragg reflection in the visible spectral range from 400 to 750 nm were experimentally observed in the course of decreasing the applied electric field. These states were assigned to different orders of Bragg’s diffraction occurring at ChOH layers with full pitch periodicity P. While the second and third orders of Bragg’s diffraction can be easily observed in conditions of standard electrooptic cell, the first order could be revealed only at very high electric field near the ‘red’ edge of the visible spectral range. For the second and third orders of diffraction there is a narrow range of electric field where both diffraction orders are observed (so-called hybrid state), with transmittance spectra of the ChOH structure showing two peaks at the short-wavelength and the long-wavelength edges of the visible spectral range. Model calculations of Bragg’s reflection of light were carried out using literature values of elasticity constants and dielectric permittivity, and the calculated plots of the selective reflection maximum vs. voltage were in good agreement with experimental data.

Review on the impact of cell phone radiation effects on green plants.

The aim of this review is to assess the impact of cell phone radiation effects on green plants. Rapid progress in networking and communication systems has introduced frequency- and amplitude-modulated technologies to the world with higher allowed bands and greater speed by using high-powered radio generators, which facilitate high definition connectivity, rapid transfer of larger data files, and quick multiple accesses. These cause frequent exposure of cellular radiation to the biological world from a number of sources. Key factors like a range of frequencies, time durations, power densities, and electric fields were found to have differential impacts on the growth and development of green plants. As far as the effects on green plants are concerned in this review, alterations in their morphological characteristics like overall growth, canopy density, and pigmentation to physiological variations like chlorophyll fluorescence and change in membrane potential etc. have been found to be affected by cellular radiation. On the other hand, elevated oxidative status of the cell, macromolecular damage, and lipid peroxidation have been found frequently. On the chromosomal level, micronuclei formation, spindle detachments, and increased mitotic indexes etc. have been noticed. Transcription factors were found to be overexpressed in many cases due to the cellular radiation impact, which shows effects at the molecular level.

Collection of nanoparticles by electrostatic precipitation operating over a wide range of electric fields

ABSTRACT In the electrostatic precipitation of microparticles, it is common to evaluate the voltages between the corona onset voltage and the breakdown point. However, the charging of particles in the nanoscale size range mainly occurs by diffusion, suggesting the possibility of its occurrence, even at low values. This paper investigates the implications of a wide range of electric fields applied in the collection of nanoparticles (6.15–241.4 nm). Two electrostatic precipitators (P.I. and P.II.), both with plates 10 cm high and 30 cm long, but with different plate spacings (4 and 6.5 cm), were tested using three air velocities (1.9, 2.9, and 3.9 cm/s) and 36 electric fields (0.0 − 5.0 kV/cm). Under the highest electric fields, both precipitators showed efficiencies above 99.9%. Furthermore, nanoparticles were collected before the corona onset voltage, with efficiencies of around 28% (P.I.) and 35% (P.II.). Even though no current was detected by the high voltage source, charges on the particles were measured in electric fields lower than 3.0 kV/cm. The higher the applied voltage, the higher the residual charge of the particles at the precipitator outlet. It is expected that the findings of this work should contribute to the technological development of electrostatic processes for air treatment.

Phase-field theory study on the modulation mechanism of oxygen vacancy concentration on charged domain wall in ferroelectric thin films

This study analyzes the regulatory mechanism of oxygen vacancy concentration on tail-to-tail charged domain walls (T–T CDWs), along with the writing time, conduction current magnitude, and retention performance of through-type T–T CDWs. The research results show that the highest density and length of T–T CDWs are achieved when the oxygen vacancy concentration is 1 × 1020 cm−3. Moreover, the successful writing of through-type T–T CDWs is limited to a certain electric field range, which is controlled by oxygen vacancy concentration. An increase in the oxygen vacancy concentration leads to a decrease in the maximum and minimum threshold electric fields required for writing through-type charged domain walls. The writing time and conductivity of through-type T–T CDWs determine the information writing speed and signal strength of domain wall memories, and the oxygen vacancy concentration also plays a regulatory role in both aspects. When the oxygen vacancy concentration is 1 × 1020 cm−3, the through-type T–T CDW exhibits the fastest writing speed, requiring only 8 ns. The magnitude of the conduction current of through-type T–T CDWs is directly proportional to the oxygen vacancy concentration. The through-type T–T CDWs formed by the aggregation of oxygen vacancies exhibit excellent retention performance, making them highly promising for applications in ferroelectric domain wall memories. Our research demonstrates that oxygen vacancies have a significant regulatory effect on the morphology and current response of charged domain walls, opening up new avenues for the study of domain wall memories.

KCSD-python, reliable current source density estimation with quality control.

Interpretation of extracellular recordings can be challenging due to the long range of electric field. This challenge can be mitigated by estimating the current source density (CSD). Here we introduce kCSD-python, an open Python package implementing Kernel Current Source Density (kCSD) method and related tools to facilitate CSD analysis of experimental data and the interpretation of results. We show how to counter the limitations imposed by noise and assumptions in the method itself. kCSD-python allows CSD estimation for an arbitrary distribution of electrodes in 1D, 2D, and 3D, assuming distributions of sources in tissue, a slice, or in a single cell, and includes a range of diagnostic aids. We demonstrate its features in a Jupyter Notebook tutorial which illustrates a typical analytical workflow and main functionalities useful in validating analysis results.

Ion-acoustic solitary waves in Mars’ lower ionosphere

This study suggests that ionic species dynamics generate electrostatic ion-acoustic solitary waves (IASWs) in Mars’ lower ionosphere. It has been determined through observations that the lower ionosphere of Mars, specifically between 200 and 350 km above the surface, is mostly made up of ions like O2+ , O +, and CO2+ , along with superthermal electrons. This study investigates the occurrence, propagation, and properties of IASWs. The derivation of the evolution equation is conducted for waves with a small-but-finite-amplitude. In order to analyze IASWs with large amplitude, the Sagdeev pseudo-potential is obtained. The model predicts the propagation of electrostatic IASWs within an electric field range of 1 to 6 mV/m and a pulse duration period of 0.5 to 4 ms. Fast Fourier analysis of the electric field pulse reveals pulses from 0.8 to 4 kHz.

Kinetics of N- to M-Polar Switching in Ferroelectric Al1-xScxN Capacitors.

Ferroelectric wurtzite-type aluminum scandium nitride (Al1-xScxN) presents unique properties that can enhance the performance of non-volatile memory technologies. The realization of the full potential of Al1-xScxN requires a comprehensive understanding of the mechanism of polarization reversal and domain structure dynamics involved in the ferroelectric switching process. In this work, transient current integration measurements performed by a pulse switching method are combined with domain imaging by piezoresponse force microscopy (PFM) to investigate the kinetics of domain nucleation and wall motion during polarization reversal in Al0.85Sc0.15N capacitors. In the studied electric field range (from 4.4 to 5.6MVcm-1), ferroelectric switching proceeds via domain nucleation and wall movement. The currently available phenomenological models are shown to not fully capture all the details of the complex dynamics of polarization reversal in Al0.85Sc0.15N. PFM reveals a non-linear increase of both domain nucleation rate and lateral wall velocity during the switching process, as well as the dependency of the domain pattern on the polarization reversal direction. A continuously faster N- to M-polar switching upon cycling is reported and ascribed to an increasing number of M-polar nucleation sites and density of domain walls.

A Piezoelectric–Piezoresistive Coupling Electric Field Sensor for Large Dynamic Range AC Electric Field Measurements

We propose a piezoelectric–piezoresistive coupling electric field sensor capable of performing large dynamic range AC electric field measurements. The electric field sensor utilizes direct coupling between piezoelectric (PE) materials and piezoresistive (PR) strain gauges, in conjunction with an external signal conditioning circuit, to measure AC electric fields effectively. We verified the feasibility of the scheme using a finite element simulation, fabricated a prototype of the electric field sensor, and characterized the properties of the prototype. The testing results indicate that the sensor exhibits an ac resolution of 50 V/m and a linear measurable electric field range of 0 to over 200 kV/m, which keeps the linearity at less than 0.94% from 1 Hz to over 5 kHz. Furthermore, the sensor also has advantages, such as a small size and low power consumption. The sensor can enhance the comprehensive observability and measurability of digital power grids.

Characterizing the electric field- and rate-dependent hysteresis of piezoelectric ceramics shear motion with the Bouc-Wen model

Piezoelectric technology is widely used in the field of precision drives. However, when piezoelectric actuators are employed at high voltages and high frequencies, their hysteresis can greatly affect the accuracy of such systems. The Bouc-Wen model has typically been used by researchers to characterise the hysteresis of piezoelectric materials. Besides, to extract the parameters of this model from experimental data, particle swarm optimization (PSO) is often employed. However, the majority of such studies only considers hysteresis as a function of the electric field strength and not as a function of actuation frequency. In addition, most of such existing reports have focused on longitudinal type piezo actuators. In this context, the research presented here complements this body of knowledge by demonstrating the application of the PSO algorithm for determining the parameters of the Bouc-Wen model when hysteresis depends not only on the electric field but also on the rate of the driving signal and when applied on a shear-type piezoelectric actuator. The obtained experimental data showed that with the increase of electric field strength, both the piezoelectric coefficient and hysteresis value increased significantly, and that with the increase of frequency, the piezoelectric coefficient decreased, while the hysteresis value changed slightly. The variations of the Bouc-Wen model parameters with the electric field and frequency were identified and then used to predict the shear motion trajectory of the piezoelectric stack. It was found that in the identified range of electric field and frequency, the predicted error rate of the hysteresis loop amplitude was less than 16.5% with a minimum value of 0.1%, and the error rate of the hysteresis loop width was less than 14.5% with a minimum value of 2.7%. Based on the identified electric field- and rate-dependent Bouc-Wen model, a novel finite element (FE) model was also proposed to analyse the effect of electrical and mechanical coupling on the piezoelectric movement.

Impact of magnetic and electric fields on the free energy to form a calcium carbonate ion-pair.

Electromagnetic fields are used in water treatment and desalination to regulate scale formation and extend the lifetime of membranes. External electric and magnetic fields can promote or suppress mineral nucleation and growth. However, the molecular-scale mechanisms of such processes remain unknown. Computing the free energies needed to form ion pairs under external fields provides important insights into understanding the elemental steps during the initial formation of mineral scales. In this paper, we used molecular dynamics combined with metadynamics simulations to investigate the free energies of forming the [Ca-CO3]0 ion pair, a fundamental building block of carbonate scales, under a range of magnetic (up to 10 T) and electric (up to 10 V m-1) fields in water. The presence of constant magnetic or electric fields favored the ion pairing reaction and lowered the free energies by up to 3% to 6%. The internal energy and entropic components of the free energy showed significant changes and exhibited non-linear behavior with increasing field strength. The [Ca-CO3]0 ion pairing is an entropy-driven process in the absence of an external field, but the mechanism shifts to an internal energy-driven process under selected external fields, suggesting possible changes in the nucleation pathways.

Lateral ambipolar drift of the excess charge carriers in the GaAs-based heterostructures with quantum wells and impurity δ-layers in the adjacent barriers

The low-temperature ambipolar photoconduction in the InGaAs/GaAs and GaAs/AlGaAs heterostructures containing the compositional quantum well (QW) tunnel-coupled with the impurity δ-well have been studied under a wide electric field range. The “stretched” bipolar drift length in the InGaAs/GaAs structure is shown to achieve a few mm at the fields of ∼70 V/cm and exceed that in the GaAs/AlGaAs structure at the comparable field strength by half an order of magnitude. The photoconductivity decay is up to several tens μs long and its behavior is fitted by the single- and “stretched-" exponent functions. The obtained results are shown to be caused by spatial separation of the non-equilibrium charge carriers in the potential profile engineered by such QW configuration and the dispersion law of holes in them.

Model-Based Theoretical Prediction of the Electric Field Dependence of the Diffusion Coefficients of Various Semiconductor Wires

This paper investigates how the diffusion coefficients of various semiconductor wires - namely Si, Ge, and 4H-SiC - are modulated by an external electric field assuming steady-state transport. This theoretical investigation consists of two steps. In the first step, we derive a model-based theoretical expression of the diffusion coefficient based on the continuity equation. Since this consideration is too simplified, in the second step, we perform Monte Carlo simulations to investigate how the electric field alters the electron occupation fraction of energy band valleys; for this, quantum mechanical scattering events during transport are calculated. Using these calculations, the electric field dependence of the diffusion coefficients of Ge and 4H-SiC wires with various cross-sectional areas is investigated because the conduction process of such materials is strongly ruled by the multi-valley transport of electrons. The obtained results reveal that the diffusion coefficient of Ge wires is constant when the electric field rises at 200 K and 400 K; but it rebounds under very high electric fields above 400 K due to the increase in the intrinsic carrier concentration. On the other hand, it is shown that the diffusion coefficient of 4H-SiC wires increases as the electric field rises in a low electric field range regardless of temperature, but it drops under high electric fields. Thus, it is considered that the theoretical models assumed for various semiconductor wires are useful in estimating the steady-state transport characteristics of scaled devices in a practical range of temperatures around room temperature.