Changes In Electrical Characteristics Research Articles

Effect of Pulse Nanosecond Volume Discharge in Air at Atmospheric Pressure on Electrical Properties of Mis Structures Based on p-HgCdTe Grown by Molecular Beam Epitaxy

The effect of the pulse nanosecond volume discharge in air at atmospheric pressure on the admittance of MIS structures based on MBE graded-gap p-Hg0.78Cd0.22Te is studied in a wide range of frequencies and temperatures. It is shown that the impact of the discharge leads to significant changes in electrical characteristics of MIS structures (the density of positive fixed charge increases), to the changes in the nature of the hysteresis of capacitance-voltage characteristics, and to an increase in the density of surface states. A possible reason for the changes in the characteristics of MIS structures after exposure to the discharge is substantial restructuring of the defect-impurity system of the semiconductor near the interface.

Radiation Effects on the On-line Monitoring System of a Hadrontherapy Center

Introduction Today, there is a growing interest in the use of hadrontherapy as an advanced radiotherapy technique. Hadrontherapy is considered a promising tool for cancer treatment, given its high radiobiological effectiveness and high accuracy of dose deposition due to the physical properties of hadrons. However, new radiation modalities of dose delivery and on-line beam monitoring play crucial roles in a successful treatment. In hadrontherapy, through interactions between the primary beam and patient’s tissue, secondary neutrons are produced. Materials and Methods This study, by using FLUKA Monte Carlo simulations, assessed the level of secondary neutron radiation, produced during patient treatment. In addition, the evaluation included secondary neutron radiation, which was produced while hitting the on-line detectors of beam delivery system by the Italian National Center for Hadrontherapy (CNAO). This study assessed the effects of secondary neutron radiation on an electronics rack (including a data acquisition system, a power supply, and a gas system) and a nozzle, where two monitoring boxes (each one consisting of two or three parallel plate ionization chambers) were installed. Results The resulting neutron energy spectra and radiation doses were used to determine the life performance and the probability of damage to these devices. Findings showed that by using carbon ions of 400 MeV/u, the fluence rate of secondary neutrons will be approximately 3.4×1010 n/cm2 in a year. Conclusion This value is lower than the experimental threshold, which is responsible for less than 1% of changes in electrical characteristics, and would cause no single event upsets.

Research on Mechanisms of Electric Conduction in the p-Type Silicon Implanted with Ne+Ions

The article presents the results of research on alternating-current electric conduction in boron-doped silicon (ρ = 10 Ω cm), strongly defected by the implantation of Ne ions (D = 1.5 × 10 cm−2, E = 100 keV). The analysis of changes in electrical characteristics recorded at the sample annealing temperature of Ta = 373 K has been presented, concerning the in uence of the testing temperature ranging from 253 K to 368 K as well as the frequency from 50 Hz to 5 MHz. The obtained results have con rmed the occurrence of two electric conduction mechanisms in strongly defected semiconductors, such as the band conduction mechanism that is characteristic of low frequency values and the jump conduction one that corresponds to higher frequencies.

Measurement of Moisture Content and Detection of Fungi on Brown Rice using Electrical Impedance Spectroscopy

Purpose of this paper is to investigate the impact of changes of moisture content and growth of fungi on the electrical impedance characteristics of brown rice. Brown rice was stored in the constant temperature and humidity chamber (30°C, 90% RH) in order to change the moisture content of brown rice. During the storage, the electrical impedance of the sample was monitored by using insertion type electrodes. As a result, the electrical impedance characteristics of brown rice were modeled by the parallel circuit model composed of resistance and constant phase element (CPE). Focusing on the relationship between moisture content and model parameters, resistive component R decreased and capacitive component C increased with increasing moisture content. Especially R has a strong exponential correlation with the moisture content. The moldy brown rice was prepared by 40 days storage under the condition of 30°C, 90% RH. As is the case with the ordinary brown rice, R decreased and C increased at higher moisture content. However, variations of these parameters with respect to the moisture content were quite small compared to the ordinary brown rice. It was considered that the changes of electrical characteristics were due to the shedding of the aleurone layer caused by the growth of fungal filament and changes in composition of brown rice by metabolism of fungi. These findings obtained from above results would be useful in evaluating the quality of brown rice.

Modification of electrical properties induced by annealing of ZnO:B thin films deposited by chemical vapour deposition: Kinetic investigation of evolution

Abstract In this study temperature dependent Hall effect measurements combined with Fourier Transformed Infra-Red (FTIR) spectroscopy measurements is used to determine the evolution of the scattering mechanisms ascribable to in-grain and grain boundaries on Boron doped ZnO thin films deposited by Low Pressure Chemical Vapour Deposition (LPCVD). Through Hall effect measurements during in situ isothermal annealing, changes in electrical characteristics of zinc oxide could be followed in real time. Whereas only degradation is observed in air, an improvement of layer conductivity could be achieved at low temperatures by annealing under argon atmosphere. A study of the conductivity during isothermal annealing offers the possibility to extract activation energies, which have been compared to migration energies of the different intrinsic defects in ZnO.

A study on H2 plasma treatment effect on a-IGZO thin film transistor

Abstract

Real‐time cell electrophysiology using a multi‐channel dielectrophoretic‐dot microelectrode array

Dielectrophoresis (DEP) has been used for many years for the analysis of the electrophysiological properties of cells. However, such analyses have in the past been time-consuming, such that it can take 30 min or more to collect sufficient data to make valid interpretations from a single DEP spectrum. This has limited the application of the technology to a rapid tool for non-invasive, label-free research in areas from drug discovery to diagnostics. In this paper we present the development of a programmable, multi-channel DEP system for rapid biophysical assessment of populations of biological cells. A new assay format has been developed for continuous near-real-time monitoring, using simultaneous application of up to eight alternating current electrical signals to independently addressable dot microelectrodes in an array format, allowing a DEP spectrum to be measured in 20 s, with a total cycle time between measurements of 90 s. To demonstrate the system, human leukaemic K562 cells were monitored after exposure to staurosporine and valinomycin. The DEP response curves showed the timing and manner in which the membrane properties changed for the actions of these two drugs at the early phase of induction. This technology shows the great potential for increasing our understanding of the role of electrophysiology in drug action, by observing the changes in electrical characteristics as they occur.

Effects of Gamma Irradiation and Electrical Stress on a-Si:H Thin-Film Transistors for Flexible Electronics and Displays

The change in electrical characteristics of a-Si:H thin-film transistors (TFTs) was determined in the presence of electrical gate bias stress, gamma radiation, and both simultaneously, simulating the harsh environment of space. Multiple TFTs were tested under each condition, and the current-voltage characteristics were measured. The results show the gate bias stress increasing the threshold voltage (VT) with power law time dependence while the gamma irradiation decreases threshold voltage for all working transistors. When both the irradiation and gate bias stress were applied simultaneously, the VT initially increased with electrical stress and then decreased as the gamma radiation dominated. Changes in effective mobility were also extracted and detailed analysis of the current-voltage characteristics indicated that the gamma radiation creates interface traps and electron-hole pairs whereas the gate stress produces defect states in the amorphous silicon.

Development of free-standing InGaN LED devices on Al2O3/Si substrate by wet etching

Free-standing InGaN-based LEDs grown on Al2O3/Si (1 1 1) have been achieved using selective area wet etching. Conventional device design was used for LED fabrication, in which p-type and n-type contacts are located at the same side of the epilayers. These LED devices were bonded to a dual in-line package (DIP), and epoxy was used to protect the front side of the epilayers as well as the bonding wires. The silicon substrate was selectively removed by wet etching while the chip was mounted in a DIP which prevented the thin film from cracking or warping. No significant change in electrical characteristics, peak emission wavelength or EL intensity versus drive current was observed. The substrate-removal process and the challenges involved are discussed. Such packaging techniques could be beneficial for commercial-scale production of InGaN-based LEDs grown on silicon substrates.

Annealing-Induced Changes in Electrical Characteristics of Al/Al-Rich $\hbox{Al}_{2}\hbox{O}_{3}/p\hbox{-Si}$ Diodes

Al-rich thin films are synthesized by radio-frequency magnetron sputtering, followed by thermal annealing at 500°C for different durations to form Al/Al-rich diodes. The annealing causes reactions at the Al-rich interface, leading to an increase in Al concentration in the interface region. As a result, the current conduction of the diode is significantly enhanced, which results in anomalous capacitance-voltage (C-V) characteristics. The anomalous behaviors can be eliminated by reconstructing the C-V curve based on a four-element circuit model. The resistance of the Al-rich layer extracted from the C-V reconstruction shows power-law voltage dependence correlated with the current-conduction measurement.

Annealing effects of In 2O 3 thin films on electrical properties and application in thin film transistors

Considering practical applications in electronic devices, we studied the growth of In 2O 3 thin films on amorphous glasses by magnetron sputtering at room temperature and annealing effect on the structural and electrical properties. The vacuum annealed In 2O 3 thin films display a grain size enlargement and preferential orientation. Electrical characterization shows that the vacuum annealed In 2O 3 thin films exhibit a significant enhancement of both electron density and mobility, while air ambient annealing leads to a remarkable drop. The mechanism of the electrical characteristic changes in In 2O 3 thin films by annealing is explored by using different scattering mechanisms. Finally, a thin film transistor device using vacuum annealed In 2O 3 nano-meter thin films as active channel material is demonstrated.

Permeabilization of Plant Tissues by Monopolar Pulsed Electric Fields: Effect of Frequency

Pulsed electric fields (PEF) nonthermally induce cell membrane permeabilization and thereby improve dehydration and extraction efficiencies in food plant materials. Effects of electrical field strength and number of pulses on plant tissue integrity have been studied extensively. Two previous studies on the effect of pulse frequency, however, did not provide a clear view: one study suggested no effect of frequency, while the other found a greater impact on tissue integrity at lower frequency. This study establishes the effect of pulse frequency on integrity of onion tissues. Changes in electrical characteristics, ion leakage, texture parameters, and percent weight loss were quantified for a wide range of pulse frequencies under conditions of fixed field strength and pulse number. Optical microscopy and viable-cell staining provided direct visualization of effects on individual cells. The key finding is that lower frequencies (f < 1 Hz) cause more damage to tissue integrity than higher frequencies (f = 1 to 5000 Hz). Intriguingly, the optical microscopy observations demonstrate that the speed of intracellular convective motion (that is, cytoplasmic streaming) following PEF application is strongly correlated with PEF frequency. We provide the first in situ visualization of the intracellular consequence of PEF at different frequencies in a plant tissue. We hypothesize that cytoplasmic streaming plays a significant role in moving conductive ionic species from permeabilized cells to the intercellular space between plant cells, making subsequent pulses more efficacious at sufficiently low frequencies. The results suggest that decreasing the pulse frequency in PEF may minimize the number of pulses needed to achieve a desired amount of permeabilization, thus lowering the total energy consumption. Practical Application: PEF cause pores to be formed in plant cell membranes, thereby improve moisture removal and potential extraction of desirable components. This study used in situ microscopic evaluation of onion cells, as they were pulsed with electric fields at different frequencies, to determine whether frequency was an important parameter. We illustrate that membranes were more effectively broken at lower frequencies as compared to higher frequencies. Application of this information will allow for improved design of PEF systems for more energy efficient dehydration or extraction of plant tissues.

Ion-implanted compliant electrodes used in dielectric electroactive polymer actuators with large displacement

Metal ion implantation is shown here as an effective technique to fabricate highly compliant electrodes at room temperature on polymer substrates. By implanting 5 keV gold ions in polydimethylsiloxane we have fabricated micron-scale electrodes that conduct at 175% strain, have low surface resistance (< 1 kΩ/square) and negligible thickness (50 nm). These electrodes have been cycled over 105 times to 30% strain with minimal change in electrical characteristics, and find applications in flexible electronics, polymer sensors and actuators. Using these ion-implanted electrodes, we have fabricated arrays of mm-size dielectric electroactive polymer actuators capable of out-of-plane deflection up to 25% with excellent stability.

A study of electrical characteristic changes in MOSFET by electron beam irradiation

Mechanisms for electrical characteristic changes in MOSFET caused by electron beam irradiation were studied using a SEM-based nano-probing system. A shift in V th occurs when a hole is trapped in a defect (oxygen vacancy) in the gate dielectric layer. Holes are generated when the plasmon is excited by electron beam irradiation. Further, an electric field is created by the positive charge-up resulting from electron beam irradiation of the ILD, causing an increase in leakage between gate and drain leading to an increase in I off. This study shows that advanced devices can be measured using a SEM-based nano-probing system without inducing electrical characteristic changes by optimizing the measurement conditions such as acceleration voltage, electron beam current, image magnification, ILD thickness, and electron beam irradiation time.

Series Gap Type 피뢰기의 뇌임펄스 동작책무 및 온도의존성에 관한 연구

This paper describes lightning impulse operating duty performance and temperature dependence of series gap type for transmission line arresters. The ageing parameters of lightning arresters are impulse current, moisture ingress, temperature ageing and so on. Especially it is important to estimate the change of electrical characteristics by lightning impulse current. In the discharge withstand test, total energy applied to the ZnO arrester each time is 4/10 , 30 kA. and in the operating duty test, the arrester has passed the test if thermal stability is achieved, if the residual voltage measured before and after the test is not changed by more than 5 %, and after the test reveals no evidence of puncture, flashover or cracking of the ZnO block. As a results, the residual voltage was in the range of 17.220.3 kV and ZnO block bear up against at 2 shot of series impulse current of 30 kA. Also it was so excellent that the mechanical destruction does not occur at the 2 groups of 5 impulses current of 2/20 10 kA. According to the tests, it is thought that the ZnO arrester shows good stability with impulse current test. and it was found that the ambient temperature is increased resistive leakage current was increased in the range 47.3167.4 .

Indium zinc oxide ohmic contact to poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) induced by UV light

In this research, we investigated the I– V characteristics of ITO/PEDOT:PSS/InZnO devices for two sets of samples. The first set is composed of PEDOT:PSS as-prepared, while the second set is composed of PEDOT:PSS irradiated by UV light source. We found that UV irradiation improves the electrical conductivity of the fabricated devices and yields to ohmic contact. Based on the UPS measurements, it was found that UV irradiation leads to an increase in the work function and the enhancement of electrical conductivity of PEDOT:PSS films. XPS and AFM measurements indicate that conformational changes of the PEDOT:PSS films are responsible for this behavior. We also studied the effect of storage on the electrical properties of our devices. No significant changes of electrical characteristics have been found after storing the devices for a period of 30 days.

Determining ionizing radiation using sensors based on organic semiconducting material

The use of organic semiconducting material sensors as total dose radiation detectors is proposed, wherein the change in conductivity of an organic material is measured as a function of ionizing radiation dose. The simplest sensor is a resistor made using organic semiconductor. Furthermore, for achieving higher sensitivity, organic field effect transistor (OFET) is used as a sensor. A solution processed organic semiconductor resistor and an OFET were fabricated using poly 3-hexylthiophene (P3HT), a p-type organic semiconductor material. The devices are exposed to Cobalt-60 radiation for different total dose values. The changes in electrical characteristics indicate the potential of these devices as radiation sensors.

In the frequency range between 1 kHz and 1 MHz

In this paper, a capacitive method for characterization of LTCC tapes in the frequency range between 1kHz and 1MHz using HP 4277A LCZ meter is presented. The principle of operation using a parallel plate capacitor and equivalent circuit as a parallel connection of capacitance and a resistor is explained and characterization of test samples is measured. The fabrication process in LTCC technology and the causes that can produce the changing of characteristic parameters of substrates in fabrication are explained in detail. We indicated the importance of knowing permittivity in the function of frequency during projecting and simulating electronic components and circuits in LTCC technology. Measurements of complex permittivity, loss tangent, Q-factor based on the proposed formulas are made for LTCC tapes samples. Small variation of measured capacitance and loss tangent is obtained, approximately about 2% in whole frequency range. The value of loss tangent is approximately the same as the value specified by manufacturers. The calculated parameters for complex permittivity have bigger values then those recommended by manufacturers before firing. In the process of sintering, sheet density and microstructure of commercial tapes are changed for all used materials, causing changes of electric characteristics, especially permittivity. In the low frequency range, below 50 kHz, there is a higher variation of characteristic parameters. In this range, the parallel resistance of the equivalent circuit is on the top level of the instruments limit and these results are not reliable. A specific user-friendly program is developed which enables automatic control of measurement, recalculation of important values and processing of results.

Investigation of Anomaly in GaN HEMTs

Electron trapping after on-state stress and hole trapping after off-state breakdown stress have been observed by comparing the electroluminescence (EL) images and electrical characteristics in high electron mobility transistors (HEMTs). Temperature measurement and two-dimensional device simulation have been done to confirm the hole-trapping phenomenon. With off-state breakdown stress, three devices all showed the same trend of electrical characteristic changes, a decrease of the threshold voltage and an increase of the gate leakage current. The changes of electrical characteristics were similar in different devices, but the changes in EL images varied. The technique promises a potential characterization tool for device and material screening.

Investigating changes of electrical characteristics of the saturated zone affected by hazardous organic waste

The Picillo Farm, EPA Superfund Site, in western Rhode Island was an unauthorized disposal site of hazardous organic chemicals. Predominantly organic contaminants have entered an aquifer comprised of layered glacial deposits and fractured bedrock and spread past the site boundaries with groundwater flow. Hydraulic conductivities in the glacial deposits range over two orders of magnitude and fractures and faults in the granitic bedrock further complicate the spreading of contaminants. Monitoring wells delineate two plumes that extend towards a fault-controlled valley with lakes and wetlands; one to the northwest and the other to the southwest. In this investigation we studied the electrical characteristics of both plumes. One dimensional Schlumberger depth soundings were conducted along several profile lines over the plumes and compared to those over non-contaminated sections of the site. With regard to the southwestern plume, high formation factors (ratio of bulk layer to pore water resistivity) between 12 and 45 were observed compared to values between 2.5 and 7.7 measured over the non-contaminated sections. Also, high values (> 5) of vertical electrical anisotropy (ratio of geoelectrically determined depth to high resistivity bedrock to drilled depth to bedrock) were measured over the contaminated part of the site. These values are extremely high compared to other non-contaminated sites (range: 2 to 3) in glacial stream channels of southern Rhode Island. Geoelectric measurements were affected by lateral effects. However, the consistency of high formation factors (11 to 35) and high vertical anisotropies (3 to 5) over the southwestern plume in comparison to low formation factors (3 to 8) and vertical anisotropies (1 to 1.5) over non-contaminated sites represents a marked difference between both sites. Overall, the Schlumberger depth soundings are less susceptible to near-surface lateral inhomogeneities than expected from other geoelectrical methods. Also, the disadvantage of a 1D interpretation was compensated by estimating resistivity and thickness ranges within the concept of non-uniqueness using the Dar Zarrouk parameters (Maillet, R., 1947. The fundamental equations of electrical prospecting. Geophysics, 12(4): 529–556.). The results over the northwestern plume, i.e. an area with higher contaminant concentration than the southwestern plume, were mixed and showed no consistent trends. Predominantly reducing conditions, as indicated by the presence of soluble ferric (FeII) iron hydroxides in ground water samples, increased the electrical conductivity. This is believed to have compensated the effect of high formation factors on the bulk saturated layer resistivity within the affected area.