High Electric Field Research Articles

Effects of Mn doping on the conduction mechanism and dielectric nonlinearity of Na0.5Bi0.5TiO3 thin film

In this work, the conduction mechanism and dielectric nonlinearity of undoped and Mn-doped Na0.5Bi0.5TiO3 (NBT) films were investigated. The potential conduction mechanism in relatively low electric fields should be dominated by hopping conduction rather than typical Ohmic conduction. In the high electric field region, the conduction mechanism is dominated by Poole–Frenkel emission and Schottky emission. The enhancement of electrical insulation of NBT films after Mn doping was shown to result from a decrease in oxygen vacancies and elevation of the conduction energy barrier. Furthermore, significant improvements in the nonlinearity of both the dielectric constant and polarization of Mn-doped NBT films were observed, as indicated by the results of Rayleigh fitting and first-order reversal curve distributions. Such enhancements were attributed to the reduction in domain wall pinning, decreased interference from electrostatic potential and improved leakage characteristics.

Fast Fabrication Nanopores on a PMMA Membrane by a Local High Electric Field Controlled Breakdown.

The sensitivity and accuracy of nanopore sensors are severely hindered by the high noise associated with solid-state nanopores. To mitigate this issue, the deposition of organic polymer materials onto silicon nitride (SiNx) membranes has been effective in obtaining low-noise measurements. Nonetheless, the fabrication of nanopores sub-10 nm on thin polymer membranes remains a significant challenge. This work proposes a method for fabricating nanopores on polymethyl methacrylate (PMMA) membrane by the local high electrical field controlled breakdown, exploring the impact of voltage and current on the breakdown of PMMA membranes and discussing the mechanism underlying the breakdown voltage and current during the formation of nanopores. By improving the electric field application method, transient high electric fields that are one-seven times higher than the breakdown electric field can be utilized to fabricate nanopores. A comparative analysis was performed on the current noise levels of nanopores in PMMA-SiNx composite membranes and SiNx nanopores with a 5 nm diameter. The results demonstrated that the fast fabrication of nanopores on PMMA-SiNx membranes exhibited reduced current noise compared to SiNx nanopores. This finding provides evidence supporting the feasibility of utilizing this technology for efficiently fabricating low-noise nanopores on polymer composite membranes.

Cross-shaped nanoaperture nanoantennas inside plasmonic nanorings for large SERS enhancement and multiple hotspots

We have designed a novel nanostructure consisting of a cross-shaped nanoaperture nanoantenna inside plasmonic nanorings for achieving very large values of electric field enhancement, as well as large theoretical surface-enhanced Raman scattering (SERS) enhancement factor, towards the center of the nanostructure. In this work, we employed Finite-difference-time-domain (FDTD) numerical modeling to simulate the plasmonic (gold) nanostructures present on silica substrates. We found that the nanostructures being proposed by us show very high localized electric field enhancements as well as multiple hotspots in which the electric field is enhanced and localized. We observed that these hotspots have large electric field enhancements (and therefore large theoretical SERS enhancement factors) at more than one wavelength. Thus, the proposed nanostructure can be used to achieve a multiple wavelength SERS response. The electric field enhancements and the resonance wavelengths of nanostructures can be tuned in the visible and the NIR region by modifying the nanostructure dimensions like the gap between the tips in the central nanoaperture structure, height of nanostructure, and tip angle variation. It is observed that as the number of gold nanorings increase, the electric field enhancement (as well as the theoretical SERS enhancement factor) also increase due to the focusing of light towards the center of nanostructure, and after the addition of a few rings, the electric field enhancement becomes almost constant. We also studied the polarization dependence of the nanostructure by varying the angle of polarization of the incident light to check the variation of the electric field of the nanostructure, and observed that the proposed nanostructures did not have much polarization dependence. Moreover, due to the symmetric nature of the plasmonic nanostructure, the position of the hotspot region shifts to the adjacent corner on rotating the incident field polarization. We optimized all the dimensional parameters to get the best possible theoretical SERS enhancement factor of ∼ 1010. Moreover, we simulated a periodic array of these plasmonic nanostructures on the silica substrates, having equal periodicity in X and Y directions, and achieved a theoretical SERS enhancement factor of ∼ 1011.

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.

Sub-PPB Detection with Gas-Phase Multiphoton Electron Extraction Spectroscopy under Ambient Conditions.

Multiphoton electron extraction spectroscopy (MEES) is an advanced analytical technique that has demonstrated exceptional sensitivity and specificity for detecting molecular traces on solid and liquid surfaces. Building upon the solid-state MEES foundations, this study introduces the first application of MEES in the gas phase (gas-phase MEES), specifically designed for quantitative detection of gas traces at sub-part per billion (sub-PPB) concentrations under ambient atmospheric conditions. Our experimental setup utilizes resonant multiphoton ionization processes using ns laser pulses under a high electrical field. The generated photoelectron charges are recorded as a function of the laser's wavelength. This research showcases the high sensitivity of gas-phase MEES, achieving high spectral resolution with resonant peak widths less than 0.02 nm FWHM. We present results from quantitative analysis of benzene and aniline, two industrially and environmentally significant compounds, demonstrating linear responses in the sub-PPM and sub-PPB ranges. The enhanced sensitivity and resolution of gas-phase MEES offer a powerful approach to trace gas analysis, with potential applications in environmental monitoring, industrial safety, security screening, and medical diagnostics. This study confirms the advantages of gas-phase MEES over many traditional optical spectroscopic methods and demonstrates its potential in direct gas-trace sensing in ambient atmosphere.

Local oscillator port integrated resonator for Rydberg atom-based electric field measurement enhancement

Rydberg atom-based superheterodyne with additional local oscillator (LO) signal is a novel approach to detect electric field with high measured sensitivity. However, the LO signal is often supplied to the atomic vapor cell by free-space illumination, which lacks mobility and integration for practical applications. Here, we present a LO port integrated split-ring resonator for realizing high sensitivity-enhanced electric field measurements. The LO signal is sent directly to the resonator through a parallel-plate waveguide, which is shown to achieve a sensitivity enhancement of 32 dB. The integrated resonator has an electrical size of 0.088λ and the feed port S11 reaches −38.2 dB.

A study of the effect of γ-radiation on the current-carrying mechanism in the P-CuTlS2 single crystal

The electrical conductivity and volt–ampere characteristics (VAC) of the p-CuTlS2 single crystal with specific resistance [Formula: see text] and irradiated by [Formula: see text]-quantum were studied in the range of 100–300[Formula: see text]K temperature and 10–104[Formula: see text]V/cm. It was determined that the cause of the conduction disorder observed in the CuTlS2 single crystal at low electric fields and high radiation doses is the formation of defect clusters dominated by cation vacancies. A sharp increase in current at high electric fields and temperatures occurs as a result of thermo-field ionization of the acceptor level with activation energy [Formula: see text][Formula: see text]eV and the ionization voltage decreases with increasing radiation dose. Based on the determination of the parameters ([Formula: see text]) that determine the mechanism of current flow, the dependence of the shape of the potential hole on the radiation dose was determined.

Influence of electric field on moisture-absorbing characteristics at the FRP/RPUF interface: experimental study and molecular dynamics simulation

The interface between fiber-reinforced polymer (FRP) and rigid polyurethane foam (RPUF) is a crucial component of composite cross-arm, not only operating within high electric field environments but also vulnerable to water-induced deterioration. In this paper, the moisture-absorbing characteristics and aging mechanism at the FRP/RPUF interface under the influence of an electric field were investigated through accelerated aging experiments, molecular dynamics (MD) simulations, reactive force filed (ReaxFF) simulations and Density Functional Theory (DFT) analysis. The results indicated that the moisture-absorbing characteristics of the FRP/RPUF system could be divided into two stages: Stage I, dominated by free diffusion, and Stage II, dominated by physical absorption. In Stage I, the electric field inhibited the diffusion behavior of water molecules by affecting the mean square displacement (MSD) of water molecules and the free volume of the FRP/RPUF system. During Stage II, the intrusion of water deepened the aging degree of the system, resulting in the emergence of a large number of free volumes and noticeable channels for water transport at the interface. The electric field enhanced the chemical reaction activity of epoxy resin and polyurethane by influencing their frontier molecular orbital energy, thereby promoting the occurrence of hydrolysis reactions. This intensified the physical moisture absorption process, ultimately promoting the Stage II process.

Normally-off GaON/p-GaN gate HEMTs with selective plasma oxidation: from structural characterization, performance improvement to physical mechanism

In this letter, a p-GaN gate high-electron-mobility transistor (HEMT) with a high threshold voltage and better gate reliability was demonstrated by using selective plasma oxidation (SPO) and an additional low-temperature annealing step before gate metal is evaporated. After the SPO, a gallium oxynitride (GaON) dielectric layer was formed on the surface of p-GaN under the gate metal, and was studied by x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry, high-resolution transmission electron microscopy and energy dispersion spectroscopy. In addition, the fabricated metal/GaON/p-GaN gate HEMT exhibited a large threshold voltage (V TH) improvement from 1.46 V to 2.47 V. Furthermore, the forward gate breakdown voltage (V GS,BD) increased from 7.55 V to 11.10 V, and the maximum forward gate operating voltage (V GS-max) significantly improved from 5.0 V to 7.80 V for a ten-year lifetime with a 63.2% failure rate. Kelvin probe force microscopy reveals that the surface potential increased after SPO, and the shift of valence band maximum obtained by XPS spectra was 0.7 eV lower than that of the p-GaN, which further improves the Schottky barrier height at the gate metal/GaON interfaces to holes, thereby improving V TH and reducing I GS of the device. As a barrier layer, GaON suppressed the injection of carrier into the depletion region under a high electric field and enhanced the reliability of the gate.

An effective microwave absorber using multi-layer Design of carbon allotrope based Co2Z hexaferrite-Polymer nanocomposite film for EMI shielding applications

This report shows impressive electromagnetic interference (EMI) shielding efficiency of laminated nanocomposites of PVDF containing binary nanofillers of rGO and Co2Z hexaferrite. These rGO layers in the PVDF matrix in association with magnetic nanofillers have been considered to improve interfacial polarization by accumulating charges at the interfaces of rGO-Co2Z hexaferrite-PVDF system. The crystallographic phase, chemical composition, and successful incorporation of the binary nanofillers into PVDF have been verified using XRD, XPS, RAMAN, and FESEM analysis. The J-E analysis of rGO-Co2Z hexaferrite-PVDF nanocomposite films confirm that the current density of all the nanocomposite films is very less and found in the order of 10-5 A/m2 under the maximum electric field of 70 kV/m. This indicates the emergence of polarization effect in the nanocomposite films when subjected to high external electric field without having electrical breakdown. The significant magnetization of ∼8.9 emu/g for nanocomposite films, at room temperature is beneficial for boosting the EMI shielding effectiveness due to absorption (SEA). The combination of magnetization and electrical polarization in nanocomposite film helps to attain significantly high total shielding effectiveness (SET) in the frequency range of 12–18 GHz. The shielding effectiveness study of both mono-layer and multi-layer nanocomposite films have been investigated. Improvement of SEA has also been achieved by the elevation of the thickness of the nanocomposite film within the range of 0.8 to 1.0 mm, which in turn improves SET to a value of −54.09 dB at 15.70 GHz for multi-layer system of thickness 0.861 mm with >99.999 % of attenuation whereas the mono-layer film of thickness 0.180 mm shows the SET of −47.03 dB at 14.76 GHz with an attenuation of >99.99 %.

Performance analysis of acoustically actuated magnetoelectric antennas via equivalent circuit method

Acoustically actuated magnetoelectric (ME) antennas based on resonant magnetoelectric coupling within ferromagnetic/piezoelectric ME laminated composites have recently been considered as a promising solution for antenna miniaturization. However, its radiation performance has been theoretically overestimated, since the negative effects on performances due to the magnetization saturation and the nonlinear mechanical behavior that occur from high-field driving have not been paid enough attention. This work presents a unique equivalent-circuit-based numerical method to analyze the near-field resonance radiation performances of ME antennas driven by high electric fields. In this method, we establish an equivalent circuit of the converse magnetoelectric effect for a ME laminated composite to describe the operating principle of acoustically actuated electromagnetic radiation. The equivalent parameters related to resonance characteristics are determined by fitting the circuit model to the data from frequency response measurements of the near-field magnetic flux density. The validity of the model is verified by comparing the theoretical predictions with the experimental results, in the view of the volume fraction dependence of the mechanical resonance-related radiation characteristics of the fabricated ME composites. Based on the proposed model, the influence of driving voltage amplitude on near-field radiation performances is further analyzed by experimental fitting to the model, and the potential limiting factors of ME antennas are discussed according to the driving-amplitude dependence of parameters obtained from the fit. This work provides an effective and engineering-friendly approach to predict the evolution of ME antenna performances, leading a way to improve the performance limit for resonant magnetoelectric coupling.

Tunable terahertz absorption of ion gel-graphene hybrids based on the Salisbury effect.

The gate-tunable absorption properties of graphene make it suitable for terahertz (THz) absorbers. However, the realization of a graphene-based THz absorber faces challenges between the difficulty of patterning graphene for processing and the intrinsically low absorbance of graphene with the high electric field needed to change the conductivity of graphene. This report presents an electrically tunable graphene THz absorber where a single-layer graphene film and a gold reflective layer are separated by a polyimide (PI) dielectric layer to form an easily fabricated three-layer Salisbury screen structure. The carrier density of the graphene layer can be efficiently tuned by a small external electrical gating (-5V-5 V) with the assistance of an ion gel layer. The voltage modulation of the Fermi energy level (EF) of graphene was confirmed by Raman spectra, and the variation of the device absorbance was confirmed using a THz time-domain spectroscopy system (THz-TDS). The measurements show that the EF is adjusted in the range of 0-0.5 eV, and THz absorbance is adjusted in the range of 60%-99%. The absorber performs well under different curvatures, and the peak absorbance is all over 95%. We conducted further analysis of the absorber absorbance by varying the thickness of the PI dielectric layer, aiming to examine the correlation between the resonant frequency of the absorber and the dielectric layer thickness. Our research findings indicate that the proposed absorber holds significant potential for application in diverse fields such as communication, medicine, and sensing.

Identification of atmospheric ozone generated from seismic activity during the occurrence of multiple earthquakes across Japan in 2022

Ground-level atmospheric ozone (tropospheric ozone) is a well-known indicator of photochemical air pollution. Atmospheric ozone may also be an indicator of earthquake generation. Ground-level observations of atmospheric ozone at multiple sites were conducted in this study at the time of multiple earthquake occurrences in Japan in 2022. As the result of this study, ozone peaks of unknown origin were detected during the occurrence of multiple earthquakes across Japan in 2022. The level of these ozone peaks began to increase from a few days to a few hours before each earthquake, reaching a maximum concentration coincident with the time of earthquake generation. ‘Unknown ozone’ were detected at near earthquake epicentres, except in the case of deep earthquakes. The ‘unknown ozone’ were also associated with earthquake seismic intensities, which were monitored at seismograph stations in various Japanese cities, towns, and villages. A laboratory experiment by Baragiola et al. (2011) indicated that ppm levels of ozone can be generated in air by the crushing and grinding of terrestrial crustal rocks, generated by exo-electrons emitted by high electric fields, resulting from charge separation during rock fracture. Baragiola et al. (2011) proposed a hypothesis whereby atmospheric ozone could be generated via rock fracturing during the occurrence of earthquakes. This hypothesis could explain the ozone peaks correlating with multiple Japanese earthquakes observed in this study. The significance of atmospheric ozone generated by seismic activity is discussed in terms of it being a possible indicator of earthquake generation and prediction.

Current transport mechanism of lateral Schottky barrier diodes on β-Ga2O3/SiC structure with atomic level interface

Heterogeneous integration of β-Ga2O3 on highly thermal conductive SiC substrate by the ion-cutting technique is an effective solution to break the heat-dissipation bottleneck of β-Ga2O3 power electronics. In order to acquire high-quality β-Ga2O3 materials on SiC substrates, it is essential to understand the influence of the ion-cutting process on the current transport in β-Ga2O3 devices and to further optimize the electrical characteristics of the exfoliated β-Ga2O3 materials. In this work, the high quality of β-Ga2O3/SiC structure was constructed by the ion-cutting process, in which an amorphous layer of only 1.2 nm was formed between β-Ga2O3 and SiC. The current transport characteristics of Au/Pt/Ni/β-Ga2O3 Schottky barrier diodes (SBDs) on SiC were systematically investigated. β-Ga2O3 SBDs with a high rectification ratio of 108 were realized on a heterogeneous β-Ga2O3 on-SiC (GaOSiC) substrate. The net carrier concentration of the β-Ga2O3 thin film for GaOSiC substrate was down to about 8% leading to a significantly higher resistivity, compared to the β-Ga2O3 donor wafer, which is attributed to the increase in acceptor-type implantation defects during the ion-cutting process. Furthermore, temperature-dependent current–voltage characteristics suggested that the reverse leakage current was limited by the thermionic emission at a low electric field, while at a high electric field, it was dominated by the Poole–Frenkel emission from E3 deep donors caused by the implantation-induced GaO antisite defects. These results would advance the development of β-Ga2O3 power devices on high thermal conductivity substrate fabricated by ion-cutting technique.

Comparison of simulations of the gas conduction in HVDC GIL by application of nonlinear conductivity model and ion-drift-diffusion model

PurposeGas insulated systems, such as gas insulated lines (GIL), use insulating gas, mostly sulfur hexalfluoride (SF6), to enable a higher dielectric strength compared to e.g. air. However, under high voltage direct current conditions, charge accumulation and electric field stress may occur, which may lead to partial discharge or system failure. Therefore, numerical simulations are used to design the system and determine the electric field and charge distribution. Although the gas conduction shows a more complex current–voltage characteristic compared to solid insulation, the electric conductivity of the SF6 gas is set as constant in most works. The purpose of this study is to investigate different approaches to address the conduction in the gas properly for numerical simulations.Design/methodology/approachIn this work, two approaches are investigated to address the conduction in the insulating gas and are compared to each other. One method is an ion-drift-diffusion model, where the conduction in the gas is described by the ion motion in the SF6 gas. However, this method is computationally expensive. Alternatively, a less complex approach is an electro-thermal model with the application of an electric conductivity model for the SF6 gas. Measurements show that the electric conductivity in the SF6 gas has a nonlinear dependency on temperature, electric field and gas pressure. From these measurements, an electric conductivity model was developed. Both methods are compared by simulation results, where different parameters and conditions are considered, to investigate the potential of the electric conductivity model as a computationally less expensive alternative.FindingsThe simulation results of both simulation approaches show similar results, proving the electric conductivity for the SF6 gas as a valid alternative. Using the electro-thermal model approach with the application of the electric conductivity model enables a solution time up to six times faster compared to the ion-drift-diffusion model. The application of the model allows to examine the influence of different parameters such as temperature and gas pressure on the electric field distribution in the GIL, whereas the ion-drift-diffusion model enables to investigate the distribution of homo- and heteropolar charges in the insulation gas.Originality/valueThis work presents numerical simulation models for high voltage direct current GIL, where the conduction in the SF6 gas is described more precisely compared to a definition of a constant electric conductivity value for the insulation gas. The electric conductivity model for the SF6 gas allows for consideration of the current–voltage characteristics of the gas, is computationally less expensive compared to an ion-drift diffusion model and needs considerably less solution time.

Modeling of inner-outer gates and temperature dependent gate-induced drain leakage current of junctionless double-gate-all-around FET

In this paper, the temperature-dependent gate-induced drain leakage (GIDL) current model is proposed with the help of a lateral electric field (EL) across the inner and outer gate interfaces of the junctionless double-gate-all-around (JL-DGAA) field-effect transistor (FET). The EL at the interface is obtained from the surface potential equation after solving the 3D Poisson equation with appropriate boundary conditions. The derived model is validated using the well-calibrated TCAD simulator platform with experimental data. A higher GIDL current at the outer gate-channel interface is observed compared to the inner gate-channel interface in the OFF-state conditions due to the high EL between the channel and drain, which is reported for the first time here. The effect of temperature (from 200 K to 500 K) on the GIDL current is also observed, which increases linearly with increasing temperature. Further, the impact of induced mechanical stress (MS) is investigated on the GIDL current, where the GIDL current increases exponentially with increasing induced MS due to effective mass and band gap reduction. Finally, the dynamic performance is investigated in terms of the gate delay time as a function of channel length and temperature. The gate delay diminishes with decreasing channel length and increasing temperature, which shows the switching speed and ability of the device.

Enhanced photothermal conversion in 3D stacked metal–organic framework nanosheets

AbstractIncorporating metal nanoparticles (MNPs) in metal–organic frameworks (MOFs) demonstrated great potential in the field of photo‐/photothermal‐catalysis. However, the oriented design and optimization of the 3D nano‐architectures of MOF substrates to achieve high‐efficiency light harvesting remains a challenge. Herein, guided on theoretical simulation, a facile etching strategy was employed to fabricate a 3D orderly‐stacked‐MOF‐nanosheet‐structure (CASFZU‐1) with a high electric field energy‐density‐distribution; well‐dispersed MNPs were afterwards encapsulated onto the MOF support. The unique nanosheet structure improved the light absorbance over the broadband spectrum, thereby enhancing the plasmonic photothermal effects of the MNPs@CASFZU‐1 composites. Based on the plasmon‐driven photothermal conversion, the MNPs@CASFZU‐1 composites exhibited approximately twofold catalytic efficiency in the hydrogenation reaction and a lower temperature for the full conversion of carbon monoxide, compared to their bulk‐type composites. The surface‐plasmon‐driven photothermal effects can be exploited in innovative MNPs@MOF platforms for various applications.

Current transport mechanisms of metal/TiO2/β-Ga2O3 diodes

β-Ga2O3 is of great interest for power electronic devices with efficiency beyond current generation Si, 4H-SiC, and GaN devices due to its large breakdown electric field of ∼8 MV/cm. However, taking advantage of this large field strength in power diodes requires device engineering to reduce leakage current that arises at high electric fields. In this work, we elucidate the current transport mechanisms of metal/TiO2/β-Ga2O3 diodes, showing that thermionic emission is an excellent descriptor of current in forward and reverse bias. It is shown that tunneling current is greatly suppressed, and consequently, that the diodes with the TiO2 interlayer can block orders of magnitude more current than Schottky barrier diodes with the same barrier heights. Finally, a 1200 V diode structure is designed based on the derived transport models, and calculated on- and off-state current characteristics closely align with those of state-of-the-art 4H-SiC commercial devices, indicating that this diode structure is ready to enable the realization of β-Ga2O3 power diodes.

Dependence of Positive Bias Stress Instability on Threshold Voltage and Its Origin in Solution-Processed Aluminum-Doped Indium Oxide Thin-Film Transistors.

The initial electrical characteristics and bias stabilities of thin-film transistors (TFTs) are vital factors regarding the practical use of electronic devices. In this study, the dependence of positive bias stress (PBS) instability on an initial threshold voltage (VTH) and its origin were analyzed by understanding the roles of slow and fast traps in solution-processed oxide TFTs. To control the initial VTH of oxide TFTs, the indium oxide (InOx) semiconductor was doped with aluminum (Al), which functioned as a carrier suppressor. The concentration of oxygen vacancies decreased as the Al doping concentration increased, causing a positive VTH shift in the InOx TFTs. The VTH shift (∆VTH) caused by PBS increased exponentially when VTH was increased, and a distinct tendency was observed as the gate bias stress increased due to a high vertical electric field in the oxide dielectric. In addition, the recovery behavior was analyzed to reveal the influence of fast and slow traps on ∆VTH by PBS. Results revealed that the effect of the slow trap increased as the VTH moved in the positive direction; this occured because the main electron trap location moved away from the interface as the Fermi level approached the conduction band minimum. Understanding the correlation between VTH and PBS instability can contribute to optimizing the fabrication of oxide TFT-based circuits for electronic applications.

Effect of bias potential and dimension on electrochemical migration of capacitors for implantable devices

Dendrite formation induced by electrochemical migration (ECM) is a common reliability problem occurring on printed circuit boards (PCBs), which significantly threatens the long-term safe operations of current implantable electronic devices (IEDs). Although several factors (i.e., contaminations, humidity, temperature) are proved to be the parameters closely related to ECM susceptibility of capacitors on a PCB under climate environments, further targeted research under other environments still needs to be conducted as ECM is highly environmental-dependent. Herein, the effects of bias potential and pitch dimension on ECM sensitivity are systematically studied using various sizes of capacitors on a test PCB under a human implantation environment. The finite element method first proves that a DC voltage pattern could be regarded as an accelerated test compared to other waveforms. Subsequent chronoamperometry tests using the DC potential further indicate that dendrite formation is closely related to pitch dimension under low bias potential, while under high bias potential electric field is also the dominating factor of dendrite formation for capacitors on a PCB. Benefiting from the electrochemical impedance spectroscopy (EIS) technique, the capacitor reliability under different corrosion states is also evaluated in a detailed manner. This work offers great value both in electronic corrosion mechanisms and future rational design for reliable IEDs.