Charge Leakage Research Articles

Degradation of Eosin Y in Water by Corona Treatment with a Dielectric Barrier Discharge Plasma

AbstractCorona treatment of Eosin Y‐contaminated water by using a dielectric material that covers the ground electrode to avoid spark discharge (causing erosion), reduce charge leakage, and improve the electric field (as stored electrons and charges) was investigated. Elimination of the organic pollutant by gas‐phase discharge above the liquid surface in a point‐to‐plate configuration with multiple needle electrodes was studied. Eosin Y was chosen as model contaminant because of its toxicity and structure that is hard to degrade. Variables such as solution conductivity, dye concentration, pH, air gap, number of needles, and electrode materials were considered. The degree of removal increases with increasing acidity, decreasing concentration, and increasing number of pins.

Charge Buildup and Leakage Current in Gold/Parylene-C/ Pentacene Capacitor under Constant-Voltage Stress

Degradation of metal-insulator-semiconductor (MIS) capacitors of gold/Parylene-C/Pentacene under constant voltage stress (CVS) was investigated to explore the electrical stability and reliability of Parylene C as a gate dielectric in flexible electronics. A stress voltage of fixed magnitude as high as 20 V, both negative and positive in polarity, was applied to each MIS capacitor at room temperature for a fixed duration as long as 10 s. The CVS effects on the capacitance-voltage curve-shift, the time-dependent leakage current and the time-dependent dielectric breakdown were measured and analyzed. CVS is observed to induce charge in Parylene-C and its interfaces with gold and Pentacene. The net induced charge is positive and negative for, respectively, negative and positive gate bias polarity during CVS. The magnitude of the charge accumulated following positive gate CVS is significantly higher than that following negative gate bias CVS in the range of 4 to 25 nC cm−2. In contrast, the leakage current during the negative gate stress is three orders of magnitude higher than that during the positive gate stress for the same bias stress magnitude. The charge buildup and leakage current are due to the trapping of electrons and holes near the Parylene-C/Pentacene interface as well as in the Parylene-C layer.Before the application of the CVS, a dielectric breakdown occurs at an electric field of 1.62 MV cm−1. After the application of the CVS, the breakdown voltage decreases and the density of the trapped charges increases as the stress voltage increases in magnitude, with the polarity of the trapped charges opposite to that of the stress voltage. The magnitude and direction of the capacitance-voltage curve-shift depend on the trapping and recombination of electrons and holes in the Parylene-C layer and in the proximity of the Parylene-C/Pentacene interface during CVS.

Colossal Magnetoelectric Effect in Core-Shell Magnetoelectric Nanoparticles.

Magnetoelectric coefficient values of above 5 and 2 V cm-1 Oe-1 in 20 nm CoFe2O4-BaTiO3 and NiFe2O4-BaTiO3 core-shell magnetoelectric nanoparticles were demonstrated. These colossal values, compared to 0.1 V cm-1 Oe-1 commonly reported for the 0-3 system, are attributed to (i) the heterostructural lattice-matched interface between the magnetostrictive core and the piezoelectric shell, confirmed through transmission electron microscopy, and (ii) in situ scanning tunneling microscopy nanoprobe-based ME characterization. The nanoprobe technique allows measurements of the ME effect at a single-nanoparticle level which avoids the charge leakage problem of traditional powder form measurements. The difference in the frequency dependence of the ME value between the two material systems is owed to the Ni-ferrite cores becoming superparamagnetic in the near-dc frequency range. The availability of novel nanostructures with colossal ME values promises to unlock many new applications ranging from energy-efficient information processing to nanomedicine and brain-machine interfaces.

Modeling the dynamic self-discharge effects of supercapacitors using a controlled current source based ladder equivalent circuit

Abstract Modeling the self-discharge effects can be very useful for the energy awareness of supercapacitors. In this paper, the conventional charge redistribution, the residual charge redistribution and the leakage of charge during self-discharge of a supercapacitor are investigated by a set of experimental results. A novel controlled current source based ladder equivalent circuit model (ECM) is proposed for depicting the dynamic self-discharge effects of the supercapacitor. The originality of the proposed model is that the controlled current source can reflect the diffusion phenomenon of the supercapacitor residual charge during rest phases. Based on the experimental data, the ladder ECM parameters are identified by the least square and bilinear transformation methods. Furthermore, the controlled current source is designed according to the identified parameters and the estimated voltage error of the ladder ECM. Validation is done based on experimentally observed results and simulation results. The comparative results show that the percent relative error of the proposed model is within 0.8%. In addition, the energy awareness and the estimated energy efficiency of the supercapacitor would also be improved by using the proposed model.

Analysis of signal attenuation in global shutter CMOS image sensor

This paper focuses on a new non-ideal phenomenon induced by the power supply crosstalk (PSC) of the row drive circuit in 8 T global shutter (GS) CMOS image sensors (CISs). A method to eliminate the non-ideal phenomenon is presented. Based on the circuit simulation, the relationship between the parasitic resistance and PSC is analyzed. The PSC would cause a charge leakage on the sampling hold (S/H) capacitors in the 8 T pixel, which in turn attenuates the output signal of the image sensor. Through the mathematical model of the in-pixel S/H circuit, the effect of PSC and exposure on signal attenuation is analyzed. To eliminate signal attenuation, this paper utilizes a separate power layout method that isolates the row drivers in different columns by using multiple power supplies. In contrast to the method of sharing the power supply, the proposed method can reduce the maximum power supply crosstalk noise from 1.17 V to 2.58 μV in the 2000 × 2 row drive array. Based on the 0.13 μm CMOS process, the measurement results of the 1st chip design using the typical shared power structure and the 2nd chip design using the separate power supply structure are compared. The measurement results show that the output signal of the 1st chip design is limited to about 303 ADU due to the power supply crosstalk. The saturated output signal of the 2nd chip design is 2200 ADU, which is in accordance with the theoretical signal output value (2200 ADU) when the pixel is saturated. The proposed method can effectively eliminate signal attenuation induced by the PSC, thereby improving the image quality of 8 T GS CIS.

Electromechanical properties of soft dissipative dielectric elastomer actuators influenced by electrode thickness and conductivity

Viscoelasticity and charge leakage are two typical dissipations of a dielectric elastomer (DE). During applied voltage loading, the electrodes tune the electromechanical deformation of DE, which results from the non-ideal insulator attribute of the DE. In this article, the influence of the electrodes is considered to establish a thorough electrodes-coupled dissipative model of DE. The effect that electrode thickness and conductivity has on the static and dynamic properties of the DE is investigated, including the electromechanical deformation of DE membrane and the voltage loaded across the thickness direction. It is found that the electromechanical deformation and voltage across the DE membrane gradually reduce with increasing electrode thickness and decreasing electrode conductivity. Resonance characteristics of the DE for varying electrode thickness and conductivity are also analyzed. The results demonstrate that electrodes with minimal thickness and high conductivity mitigate the resonant frequency and enhance the vibration intensity of the DE system.

Investigation of charge multiplication in irradiated p-type silicon strip sensors designed for the ATLAS phase II tracking detector

Future particle accelerator experiments, for example the High Luminosity-LHC (HL-LHC) in 2025, will demand a much higher radiation hardness of silicon strip sensors due to high fluences and long operation times. New p-type strip sensors have been developed and their charge collection behavior as well as their electrical performance have been investigated. Additionally the long-term behavior under operation has to be investigated and understood. In previous studies of the annealing behavior, the phenomenon of charge multiplication appeared in highly irradiated and/or long-term annealed sensors. This phenomenon is now thoroughly investigated within this study for ATLAS12 strip sensors irradiated to fluences ranging from 5⋅1014neq∕cm2 to 2⋅1015neq∕cm2. Therefore systematic charge collection, leakage current and electric field measurements have been carried out at several annealing temperatures between 23°C and 80°C to investigate the dependence on temperature and fluence. The stability, temperature effects and the maximum amount of multiplication reachable were investigated. Severe changes in the signal pulses in time were observed with increasing amount of annealing. The pulse duration started to increase for enhanced charge multiplication, exceeding the readout shaping time of the ALIBAVA system.

Single electron–hole pair sensitive silicon detector with surface event discrimination

We demonstrate single electron–hole pair resolution in a single-sided, contact-free 1 cm2 by 1 mm thick Si crystal operated at 48 mK, with a baseline energy resolution of 3 eV. This crystal can be operated at voltages in excess of ±50 V, resulting in a measured charge resolution of 0.06 electron–hole pairs. The high aluminum coverage (∼70%) of this device allows for the discrimination of surface events and separation of events occurring near the center of the detector from those near the edge. We use this discrimination ability to show that non-quantized dark events seen in previous detectors of a similar design are likely dominated by charge leakage along the sidewall of the device.

Schottky Contacts on Polarity-Controlled Vertical ZnO Nanorods.

Polarity-controlled growth of ZnO by chemical bath deposition provides a method for controlling the crystal orientation of vertical nanorod arrays. The ability to define the morphology and structure of the nanorods is essential to maximizing the performance of optical and electrical devices such as piezoelectric nanogenerators; however, well-defined Schottky contacts to the polar facets of the structures have yet to be explored. In this work, we demonstrate a process to fabricate metal-semiconductor-metal device structures from vertical arrays with Au contacts on the uppermost polar facets of the nanorods and show that the O-polar nanorods (∼0.44 eV) have a greater effective barrier height than the Zn-polar nanorods (∼0.37 eV). Oxygen plasma treatment is shown by cathodoluminescence spectroscopy to affect midgap defects associated with radiative emissions, which improves the Schottky contacts from weakly rectifying to strongly rectifying. Interestingly, the plasma treatment is shown to have a much greater effect in reducing the number of carriers in O-polar nanorods through quenching of the donor-type substitutional hydrogen on oxygen sites (HO) when compared to the zinc-vacancy-related hydrogen defect complexes (VZn-nH) in Zn-polar nanorods that evolve to lower-coordinated complexes. The effect on HO in the O-polar nanorods coincides with a large reduction in the visible-range defects, producing a lower conductivity and creating the larger effective barrier heights. This combination can allow radiative losses and charge leakage to be controlled, enhancing devices such as dynamic photodetectors, strain sensors, and light-emitting diodes while showing that the O-polar nanorods can outperform Zn-polar nanorods in such applications.

A Semi‐Floating Memory with 535% Enhancement of Refresh Time by Local Field Modulation

AbstractThe recently proposed semi‐floating gate memory technology shows the potential to balance conflicts between writing speed and data storage. Although the introduction of the p–n junction greatly improves device writing speed, the inevitable junction leakage limits the further extension of data retention time. A local nonvolatile electric field is introduced by exploiting the polarization of ferroelectric gate dielectric HfZrO4 to modulate the charge leakage speed of the p–n junction since the carrier density of 2D materials can be efficiently regulated. The refresh time is greatly prolonged more than 535%, solving the bottleneck problem of relatively short retention time of previous semi‐floating gate memory. In addition, the characteristics of device under low operation voltage is also explored, which can serve for further power reducing. This design realizes the combination of ultrafast writing operation and significant enhanced data retention ability, which provides a new idea of the development for high speed non‐volatile memory technology.

Modeling of Impact Ionization and Charge Trapping in SuperCDMS HVeV Detectors

A model for charge trapping and impact ionization, and an experiment to measure these parameters is presented for the SuperCDMS HVeV detector. A procedure to isolate and quantify the main sources of noise (bulk and surface charge leakage) in the measurements is also describe. This sets the stage to precisely measure the charge trapping and impact ionization probabilities in order to incorporate this model into future dark matter searches.

Driving Waveform Design with Rising Gradient and Sawtooth Wave of Electrowetting Displays for Ultra-Low Power Consumption.

As a kind of paper-like display technology, power consumption is a very important index for electrowetting displays (EWDs). In this paper, the influence of driving waveforms on power consumption of the EWDs is analyzed, and a driving waveform with rising gradient and sawtooth wave is designed to reduce the power consumption. There are three stages in the proposed driving waveform. In the initial stage, the driving voltage is raised linearly from the threshold to the maximum value to reduce the invalid power consumption. At the same time, the oil breakup can be prohibited. And then, a section of sawtooth wave is added for suppressing oil backflow. Finally, there is a section of resetting wave to eliminate the influence of charge leakage. Experimental results show that the power consumption of the ultra-low power driving waveform is 1.85 mW, which is about 38.13% lower than that of the conventional used square wave (2.99 mW), when the aperture ratio is 65%.

Comparing the Levelized Cost of Returned Energy (LCORE) Values for Hydrogen-Based Conversion Pathways and Batteries

A method for analyzing the levelized cost of conversion, storage, and return of input energy as an end product net of losses with a zero cost of input energy, termed the levelized cost of returned energy (LCORE), is introduced and applied uniformly to compare the net conversion and storage costs of various renewable electrolysis technologies and hydrogen end-uses with battery and flow-battery energy storage technologies. The LCORE methodology accounts for capital costs, financing costs, operation and maintenance costs, energy efficiency of each step, technology lifetime, and replacement costs. Results show that the most valuable use of the renewable hydrogen is as fuel for fuel cell electric vehicles, although the costs of the hydrogen fueling infrastructure are estimated to be high using the existing paradigm of trucking, compression, and dispensing (adding more than $7/kilogram to the price of hydrogen). Importantly, the analyses show that the range of costs for pathways that produce hydrogen by electrolysis from renewable generation and return it to the electric grid using the natural gas system to transport the hydrogen to an existing combined cycle plant to produce the electricity have costs of $76–$210/MWh. These costs are directly competitive with battery energy storage pathways at $51–$150/MWh while also providing energy storage over durations as long as months, durations that are that are not technically feasible for many battery technologies due to charge leakage.

Recent progress in indoor organic photovoltaics.

Among various potential applications of organic photovoltaics (OPVs), indoor power generation has great potential because of several advantages over outdoor light harvesting under 1 sun conditions. Commonly used indoor light sources have narrower emission spectra with lower intensity (by 3 orders of magnitude) as compared to the solar spectrum. Highly tunable optical absorption, large absorption coefficients, and small leakage currents under dim lighting conditions make OPVs promising candidates for indoor applications. For optimizing indoor photovoltaic materials and devices, several key issues (different from those under 1 sun conditions), such as developing new indoor photovoltaic materials and devices with suitable absorption spectra, large open-circuit voltages with low energy loss, minimized trap-mediated charge recombination and leakage currents, and device stability under indoor conditions, should be considered carefully. In this review, the recent progress in optimization of indoor photovoltaic materials and devices, and the key strategies to optimize the indoor photovoltaic characteristics will be summarized and discussed.

A 7b 400 ​MS/s pipelined SAR ADC in 65 ​nm CMOS

This paper presents a 7-bit 400-MS/s pipelined successive approximation register (SAR) analog-to-digital converter (ADC) with high reliability. To meet the high demand for medium resolution and high sampling speed, a modified switching scheme is adopted to resolve charge leakage problem and to improve the reliability of SAR ADC. Compared to the conventional architecture, the modified bootstrapped switch which uses two sampling MOSFETs is employed to increase the uniformity of sampling voltage and save the chip area. In addition, three parallel comparators are controlled by a novel asynchronous clock generator to minimize the latching error. The measurement result shows that the ADC, implemented in the 65-nm CMOS process, achieves the 40.83 dB signal-to-noise and distortion ratio (SNDR) and 64.75 dB spurious-free dynamic ranges (SFDR) at 400-MHz sampling frequency without additional digital calibration.

A Silicon Surface Code Architecture Resilient Against Leakage Errors

Spin qubits in silicon quantum dots are one of the most promising building blocks for large scale quantum computers thanks to their high qubit density and compatibility with the existing semiconductor technologies. High fidelity single-qubit gates exceeding the threshold of error correction codes like the surface code have been demonstrated, while two-qubit gates have reached 98% fidelity and are improving rapidly. However, there are other types of error --- such as charge leakage and propagation --- that may occur in quantum dot arrays and which cannot be corrected by quantum error correction codes, making them potentially damaging even when their probability is small. We propose a surface code architecture for silicon quantum dot spin qubits that is robust against leakage errors by incorporating multi-electron mediator dots. Charge leakage in the qubit dots is transferred to the mediator dots via charge relaxation processes and then removed using charge reservoirs attached to the mediators. A stabiliser-check cycle, optimised for our hardware, then removes the correlations between the residual physical errors. Through simulations we obtain the surface code threshold for the charge leakage errors and show that in our architecture the damage due to charge leakage errors is reduced to a similar level to that of the usual depolarising gate noise. Spin leakage errors in our architecture are constrained to only ancilla qubits and can be removed during quantum error correction via reinitialisations of ancillae, which ensure the robustness of our architecture against spin leakage as well. Our use of an elongated mediator dots creates spaces throughout the quantum dot array for charge reservoirs, measuring devices and control gates, providing the scalability in the design.

Carbon electrodes with ionic functional groups for enhanced capacitive deionization performance

Capacitive deionization (CDI) has proved to be a clean and green technology; however, the charge leakage in the electrode pores during the adsorption-desorption cycles lowers the desalination efficiency. In this work, commercially available activated carbon was chemically treated to give the activated carbon surface either immobilized amino groups or sulfonic acid groups. The amino group-containing and sulfonic group-containing carbon materials were used as anode and cathode electrodes, respectively, in assembling a CDI (AC-CDI) cell. The salt adsorption capacity, salt removal efficiency, and charge efficiency of the AC-CDI cell were over two times higher than those of the untreated carbon-based CDI cell and comparable with those of the membrane CDI (MCDI) cell. The greatly improved desalination performance of the AC-CDI cell was attributed to enhanced wettability, faster diffusion of counter ions to each electrode via electrostatic attraction, and the prevention of re-adsorption of ions via repulsion between the charged layers and co-ions during adsorption-desorption cycle. Thus, it can be concluded that chemically modified carbon-based CDI cell is highly promising for practical application.

Cytoprotective Effects of Dinitrosyl Iron Complexes on Viability of Human Fibroblasts and Cardiomyocytes.

Nitric oxide (NO) is an important signaling molecule that plays a key role in maintaining vascular homeostasis. Dinitrosyl iron complexes (DNICs) generating NO are widely used to treat cardiovascular diseases. However, the involvement of DNICs in the metabolic processes of the cell, their protective properties in doxorubicin-induced toxicity remain to be clarified. Here, we found that novel class of mononuclear DNICs with functional sulfur-containing ligands enhanced the cell viability of human lung fibroblasts and rat cardiomyocytes. Moreover, DNICs demonstrated remarkable protection against doxorubicin-induced toxicity in fibroblasts and in rat cardiomyocytes (H9c2 cells). Data revealed that the DNICs compounds modulate the mitochondria function by decreasing the mitochondrial membrane potential (ΔΨm). Results of flow cytometry showed that DNICs were not affected the proliferation, growth of fibroblasts. In addition, this study showed that DNICs did not affect glutathione levels and the formation of reactive oxygen species in cells. Moreover, results indicated that DNICs maintained the ATP equilibrium in cells. Taken together, these findings show that DNICs have protective properties in vitro. It was further suggested that DNICs may be uncouplers of oxidative phosphorylation in mitochondria and protective mechanism is mainly provided by the leakage of excess charge through the mitochondrial membrane. It is assumed that the DNICs have the therapeutic potential for treating cardiovascular diseases and for decreasing of chemotherapy-induced cardiotoxicity in cancer survivors.

Sensorless adaptive sliding mode position control for piezoelectric actuators with charge leakage

Position control of piezoelectric actuators is greatly affected by nonlinearities such as hysteresis and creep. Therefore, precise position sensors must be utilized which have high cost and complicated structures in micro scales. Charge-based position estimation is an alternative method which resorts to piezoelectric linear charge-position property to estimate the actuator position, but in low-impedance actuators, there is a charge leakage caused by actuator internal resistance which deteriorates the position estimation and closed-loop control performance. In this article, the leakage is considered as a sensor fault. Therefore, a combination of charge measurement method and an appropriate observer is designed to detect and isolate the mentioned fault and estimate the actuator position properly. In addition, an adaptive sliding mode control procedure is proposed for trajectory tracking in the presence of estimated states. The required analysis is carried out to guarantee the closed-loop stability. Finally, experimental results show the effectiveness of the proposed method.

Influence of active layer thickness on photovoltaic performance of PTB7:PC70BM bulk heterojunction solar cell

Abstract In this paper, we studied the effect of active layer thickness on the photovoltaic performance of inverted bulk heterojunction (BHJ) organic solar cell (OSC). The capacitance-voltage (C–V), dark current-voltage (I–V) and impedance spectroscopy (IS) analysis were carried out to explain the active layer thickness dependence on the photovoltaic performance. The OSC with an active layer thickness of 150 nm achieved the best power conversion efficiency (PCE) of 5.87%, while the OSC of 200 nm active layer thickness yielded the worst PCE. Reduction in the fill factor (FF) was the main reason for the reduction in the PCE at large active layer thickness. The dark I–V analysis revealed large defect density for the OSC with active layer thickness of 200 nm, which raised the charge recombination and leakage current and consequently reduced the FF. IS analysis predicted that the charge transport became the serious limitations for the OSC with 200 nm thick active layer, which can be attributed to the weakening of electric field as well as creation of field-free regions. It mainly caused a drastic drop in the fill factor by reducing the charge collection efficiency, consequently deteriorated the photovoltaic performance.