Electrical Breakdown Characteristics Research Articles

Characteristics of electric breakdown in repeated frequency pulse with microcavity effect

The electric breakdown characteristics in microcavity structure under repeated frequency pulse (RFP) were studied, and the physical mechanism was investigated quantitatively based on the full statistical distribution of breakdown time delay obtained in step rectangular pulse (SRP). Experimentally, microcavity heights of 300, 800, and 2000 μm were used. In RFP, the occurrence of breakdown becomes probabilistic when the time delay t d and pulse width t PW satisfy the condition t s-min < t PW < t s-max. The breakdown probability increases with pulse width, and the probability distributions are roughly exponential and Gaussian at pulse frequencies of 3 and 1000 Hz, respectively. We found the results are attributed to the similar distributions of time delay in RFP and SRP with similar afterglow time and pulse voltage, and the equal distributions of breakdown probability (with pulse width) and cumulative probability of t d in RFP. The microcavity effect will decrease the breakdown probability under given pulse width and voltage. Additionally, it is found that in RFP the increase of pulse width from 1 to 1000 μ s will decrease the threshold voltages at 0% and 100% breakdown probabilities, and the threshold voltage difference will decrease simultaneously to around 0, which results in the transition of breakdown feature from probability to certainty. This phenomenon is due to that the reduction of pulse voltage will increase the time delay significantly and meanwhile the variation rate of time delay with pulse voltage Δt d/ΔU w decreases sharply. The microcavity effect will cause the increase of threshold breakdown voltages at a given pulse width and frequency. Finally, it is found that in RFP the breakdown voltage will decrease with the rise of pulse frequency from 10° to 104 Hz, which is consistent with the variation of time delay with afterglow time (from 10−1 to 103 ms) in the memory curve measured in SRP under similar afterglow time. Overall, the microcavity effect will enhance the adsorption of charged and excited species by dielectric walls during afterglow period and enlarge the time delay in the following pulse breakdown, and then influence the RFP breakdown characteristics.

Electrical breakdown characteristics of nanogaps

Understanding electrical breakdown in nanogaps is essential for the performance of electronic devices and plasma applications

Review of electron emission and electrical breakdown in nanogaps

With the continual miniaturization of electronic devices, there is an urgent need to understand the electron emission and the mechanism of electrical breakdown at nanoscale. For a nanogap, the complete process of the electrical breakdown includes the nano-protrusion growth, electron emission and thermal runaway of the nano-protrusion, and plasma formation. This review summarizes recent theories, experiments, and advanced atomistic simulation related to this breakdown process. First, the electron emission mechanisms in nanogaps and their transitions between different mechanisms are emphatically discussed, such as the effects of image potential (of different electrode's configurations), anode screening, electron space-charge potential, and electron exchange-correlation potential. The corresponding experimental results on electron emission and electrical breakdown are discussed for fixed nanogaps on substrate and adjustable nanogaps, including space-charge effects, electrode deformation, and electrical breakdown characteristics. Advanced atomistic simulations about the nano-protrusion growth and the nanoelectrode or nano-protrusion thermal runaway under high electric field are discussed. Finally, we conclude and outline the key challenges for and perspectives on future theoretical, experimental, and atomistic simulation studies of nanoscale electrical breakdown processes.

Surface passivation properties of atomic-layer deposited hafnium oxide on a (100) β-Ga2O3 MOSFET

We report the effect of HfO2 passivation on the electrical characteristics of (100) β-Ga2O3 metal-oxide-semiconductor field-effect transistors (MOSFETs). The atomic-layer-deposited HfO2 layer with negative defect charges enhances the transconductance and subthreshold slope. A significant positive threshold voltage (V TH) shift of ∼32 V is induced after the passivation. Moreover, significantly less V TH shift of ∼2 V is observed under negative bias stress (NBS) for 3600 s in comparison with an Al2O3 passivated and unpassivated device. Physics-based technology computer aided design (TCAD) simulation is performed to demonstrate the surface depletion effect and the dependency on the density of negative fixed charges in the HfO2 passivation layer. Finally, the HfO2 passivated device maintains superior electrical characteristics compared to the unpassivated device at a temperature of up to 500 K.

Novel Electrical Insulation Coatings for HTS Cables

To develop epoxy based electrical insulation for HTS power cable and other device applications, the suitability of two cryogenic rated commercial epoxies, (MASTERBOND EP29-LPSP and EP37-3FLFAO) were evaluated. Characterization of their electrical breakdown characteristics, mechanical strength, and the interfacial shear strength of the interface with HTS tapes were conducted at room temperature and 77 K. The epoxy materials are ductile at cryogenic temperatures to support their use as electrical insulation of HTS power devices.

Band Alignment of β-Ga2O3 with BaTiO3, SrTiO3, and Related Composites

Integrating perovskite oxides BaTiO3 (BTO), SrTiO3(STO) with β-Ga2O3 is of great interest for developing β-Ga2O3 power devices due to its promotion for improving uniformity in the electric field profile and breakdown characteristics. In this work, β-Ga2O3/BaTiO3 (BTO), β-Ga2O3/SrTiO3 (STO), β-Ga2O3/Ba0.5Sr0.5TiO3 (BSTO) heterojunction were epitaxially grown on sapphire substrates by low-pressure chemical vapor deposition (LPCVD) and radio frequency physical vapor deposition (RF PVD). The energy band alignment of β-Ga2O3/BaTiO3, β-Ga2O3/SrTiO3, β-Ga2O3/Ba0.5Sr0.5TiO3 (BSTO) heterojunction have been analyzed by X-ray photoemission spectroscopy and UV–visible transmittance spectrum. The conduction band offsets (∆E c ) of β-Ga2O3/BTO, β-Ga2O3/STO, β-Ga2O3/BSTO is found to be 0.32 ± 0.05, 1.15 ± 0.05, 0.78 ± 0.05 eV, respectively; and the valence band offsets (∆E v ) of these heterojunction is 0.76 ± 0.05 eV, 0.55 ± 0.05 eV, and 0.73 ± 0.05 eV, respectively. Our results indicate that type-I band alignment respectively form at these heterojunction, in which the valence and conduction bands of β-Ga2O3 are concomitantly higher than those of BTO, STO, and BSTO. The accurate determination of ∆E c and ∆E v is important for the design of β-Ga2O3/ferroelectric heterojunction multifunctional devices.

A Study on the Electrical Breakdown Characteristics of Liquid Nitrogen for the Design of Superconducting Apparatuses

A Study on the Electrical Breakdown Characteristics of Liquid Nitrogen for the Design of Superconducting Apparatuses

Physical and Electrical Breakdown Characteristics of Oil-Impregnated Kenaf Paper with the Introduction of External PVA for Transformer Application

This work examines the physical and electrical breakdown characteristics of kenaf paper coated with Polyvinyl Alcohol (PVA) for application in power transformers. The paper was made from kenaf bast fibers using the soda pulping method, whereby the pulps were subjected to 12,000 beating revolutions. PVA with weight percentage concentration up to 6% was introduced to the beaten kenaf through a spin coating approach. The structure of the kenaf paper was examined through Scanning Electron Microscopy (SEM). The physical properties examined were apparent density, Tensile Index (TI), Burst Index (BI), and Tear Index (TeI), while AC breakdown voltage and strength were analyzed for the electrical property. It is found that the beating and external PVA improve the kenaf paper’s apparent density, TI, BI, and AC breakdown strength while the TeI decreases.

Effect of SiO2 particle size scale on the electrical performance of epoxy‐based nonlinear conductive composite

AbstractIn this paper, SiO2 particles with three particle sizes of 60 nm, 2 μm, and 25 μm were added as fillers into the composites prepared by epoxy resin and micron silicon carbide to investigate the mechanism of SiO2 particle size on the nonlinear electrical conductivity and breakdown characteristics of the composites. Compared with SiC/EP composites, the smaller the added SiO2 particle size, the lower the current density at high fields and the higher the breakdown field strength of SiO2/SiC/EP composites. The nonlinear coefficients of SiO2/SiC/EP composites increased slightly with the addition of 1phr 25 μm SiO2 and 4phr 2 μm SiO2, and the breakdown field strengths were increased by 55.36% and 66.77%, respectively. The SiO2/SiC/EP composites with the addition of 4phr 60 nm SiO2 particles showed the most significant attenuation of the conductivity current and the most prominent enhancement of the breakdown field strength, but the nonlinear coefficient was reduced by 24.6%. With the increase of SiO2 doping amount, compared with the composites with the same particle size and low doping amount, the larger the SiO2 particle size, the decrease of the current density of the composites under high field intensity is more obvious, and the dielectric constant drops even more.

Changes of cross-linked network and DC electrical properties of nanocomposite silicone rubber under thermal aging

Nano dielectrics have brought hope for solving the problem of cable insulation at high voltage levels. In this paper, nano Al2O3 and MgO are doped to silicone rubber and the nanocomposites are aged at 200 °C for 0-80 days. The electrical conductivity and DC breakdown characteristics of aged materials are investigated. The microscopic and elemental properties are also analysis. It is found that with the increase of thermal aging time, electrical conductivity of all sets decreases first and then increases, while the DC breakdown voltage experiences a process of first increasing and then decreasing. During the initial aging process, secondary vulcanization of silicone rubber occurs, however, the cross-linked network degrades with further aging, which could explain the changes in electrical properties. The introduction of metal oxides could react with exfoliated radicals to form s table compounds, thus, the performance of Al2O3 and MgO doped materials have better electrical properties under thermal aging.

Double dielectrics enhancement on the LDMOS using high-k field dielectric and low-k buried dielectric

This paper investigates the double dielectrics enhancement LDMOS (DDE LDMOS) with high-k field dielectric and low-k buried dielectric. The analytical models of the potential and electric field, optimal breakdown voltage and drift doping concentration are established for this novel LDMOS. The validity of the analytical models is confirmed by the simulation results. Based on the analytical and simulated results, the modulation mechanism of the high-k field dielectric and low-k buried dielectric on the electric field and breakdown characteristics of DDE LDMOS are analyzed and compared. Compared to the conventional LDMOS, the specific on-resistance of DDE LDMOS is reduced by 19%, the breakdown voltage and figure of merit (FOM) of the DDE LDMOS can be improved by 62% and 222.4% when the permittivity of high-k field dielectric and low-k buried dielectric are 100 and 2. Meanwhile, the transfer characteristic, output characteristic, frequency characteristic, and switching characteristic of the DDE LDMOS are also discussed.

An investigation of improved titanium/titanium nitride barriers for submicron aluminum-filled contacts by energy-filtered transmission electron microscopy

Abstract The adaptation of titanium/titanium nitride barriers which are commonly used for tungsten-filled contacts to aluminum-filled contacts has encountered some limitations. A main issue is the decomposition of titanium nitride manufactured by physical vapour deposition through reaction with aluminum. In this investigation two different concepts for barrier improvement have been pursued: 1. stuffing of a conventional barrier by a rapid thermal process in an oxygen-rich atmosphere and, 2. use of a barrier manufactured by chemical vapour deposition. The aim of the transmission electron microscopic analysis was to explain different electrical breakdown characteristics during thermal stressing of chips with these barriers. Energy-filtered transmission electron microscopy was used to monitor elemental distributions down to nanometer scale. Both concepts are found to improve barriers for aluminumfilled contacts.

전계불평등도에 따른 대기압 공기 절연파괴특성 분석

In this study, electrical breakdown characteristics of atmospheric air under the AC and lightning Impulse(LI) voltage waveforms were investigated to settle the electrical insulation design criteria for air insulated switchgear. To investigate the electrical breakdown characteristics according to the non-uniformity of electric field, needle-plane and 4 kinds of sphere-plane electrodes were used as the tested electrode system. Through the experimental results, it was found that when positive impulse voltage is applied, it can be the weakest in terms of electrical insulation. As for the positive LI breakdown voltage, in the case of electrodes with high non-uniformity such as needle-plane electrode, it was confirmed that electrical breakdown voltage increased almost linearly with the gap length. Based on the experimental and electric field analysis results, it is found that it is desirable to establish the air insulation design/evaluation criteria as a function according to the distance in electrodes with high non-uniform electrode systems, and as a maximum electric field function in the quasi electrode systems. Moreover, maximum electric field for partial discharge (PD) inception decreased as the cross-sectional area of the electrodes facing each other increased.

Electric Field Distribution and AC Breakdown Characteristics of Polluted Novel Lightning Protection Insulator under Icing Conditions

As a result of lightning strikes, pollution, and ice, overhead distribution wires might be short-circuited and trip. As a result, researchers have developed a new lightning protection composite insulator. There is still a need to test its pollution and icing performance. Based on the finite element and field test method, this paper studies the electric field distribution and AC (Alternating Current) breakdown characteristics of polluted novel lightning protection insulators under icing conditions. Firstly, the finite element calculated results show that this novel insulator’s electric field distribution is different from that of a conventional insulator. The locations with sizeable electric fields are located in the insulation section, and the electric field in the arrester section is tiny. In addition, when the insulator surface is covered with ice, there is an increase in the electric field along the surface and pin electrodes. Compared with the dry conditions, when there is an ice layer and icicle, electric field peaks increase by 48.85% and 46.08%, respectively. Secondly, the test results show that there are three types of arc paths in different pollution levels. The arc paths are related to ESDD (equivalent salt deposit density) under icing conditions. Uf shows a downward trend with increased pollution levels, and the maximum flashover voltage is 2.70 times more than the minimum. Finally, four fitting methods are proposed in this paper. After comparing the goodness of fit of different functions, the quadratic function and negative power function with the constant term are recommended as empirical formulas for calculating flashover voltage of novel insulators under icing conditions in different pollution levels. The research results of this paper have a specific guiding role for the selection of the external insulation of transmission lines and structural optimization of novel insulators.

Electrical breakdown characteristics of soil under dc high voltage

Traditionally, the studies on electrical discharges for soil remediation primarily focus on the degradation efficiency and reaction pathways of various types of discharges for various types of contaminants. In comparison, less attention has been paid on the investigation on the physical property of the plasma initiation and development process, which is essential for the generation of reactive species responsible for plasma-related reactions. In this paper, the electrical and optical behaviors of corona discharge in soil produced by negative DC high voltage are investigated. The images of the discharge are recorded, and the influence of different operating variables, including applied voltage, soil density, soil particle size, and water content level, on the discharge streamer structure and plasma temperature are examined through experiments. Possible mechanisms that could contribute to the observed phenomenon are discussed.

Experimental Investigation of the Triple-Junction Effect on the Electric Discharge Characteristics and Modeling of the Maximum Discharge Current

The electrical discharge and breakdown characteristics of a triple junction (TJ) in high voltage (HV) electrical insulation are becoming an important issue in recent industrial applications. In this paper, a comparative study is conducted between three insulation materials used in HV: silicone, porcelain, and heat tempered glass, with electrode shape parameters such as inter-electrode distance (d), applied voltage (V), and geometry investigated for positive polarity, using an experimental approach. For optimum test organization to support our research and highlight the parameters and their interactions, we have established a mathematical regression model of the discharge current. It is polynomial, with good performance and a high level of precision. Besides, this yields one monovariable and another two-variable quadratic model. The latter can simulate the electric discharge simultaneously with two variables: V and d, and an adjusted determination coefficient () of nearly 0.99. Consequently, the two-variable quadratic model has been adapted to V and d ranges of 10 to 50 kV and 1.9 to 8 cm, respectively. Finally, this study provides us with new applicable knowledge about the TJ effect on electrical insulation with recommendations to optimize the design for higher performance.

Electrical Breakdown Characteristics of Polypropylene for an Eco-Friendly Power Cable

Cross Linked Polyethylene (XLPE) has been widely used as an insulation material of a power cable due to its excellent electrical and mechanical properties. XLPE may cause an environmental devastation because it is not recyclable due to its thermosetting characteristics. Therefore, it is necessary to develop an insulation material which could be replaced with the conventional XLPE owing to its eco-friendly and good dielectric characteristics. In this paper, an analytic study on the comparison between conventional XLPE and six types of eco-friendly polypropylene (PP) samples developed by Hu-innovation Co. Ltd is conducted. As a result, the dielectric characteristics of PP according to manufacturing process are analyzed.

The Streamers Dynamics Study by an Intelligent System Based on Neural Networks

The formation and propagation of streamers is an important precursor to determine the characteristics of electrical breakdown of many HV electrode configurations. Understanding of the study of the interaction between the polymer surface and the development process of the streamer is of major importance when we want to improve internal and external performance insulation systems. In this context, a numerical tool using neural networks is developed. This model allows evaluating the speed of streamers as a function of the amplitude of voltage initiation and the nature of the insulating materials. For this, a database was created to train the neural model from a laboratory model. This investigation builds a database for predicting the propagation of streamers on the polymers surface by different neuronal methods and this presents an interesting tool for estimating the propagation phenomena in functions of very important parameters

Electric stress and dielectric breakdown characteristics under high-frequency voltages with multi-harmonics in a solid-state transformer

Mixed-frequency electric stress and the thermal issue by rapid semiconductor switching and circuit topology cause the unexpected insulation breakdown, indicating a key issue on medium-high frequency (MF-HF) transformers. This work focuses on the effects of frequency and temperature on the breakdown strength of used epoxy resin insulation. An experimental method containing the power supply and breakdown measurement unit was constructed under high sinusoidal voltages with harmonic components. A continuous boost method was used to induce dielectric breakdown. Meanwhile, high voltage and current probes were employed to capture the breakdown voltage and current waveforms. The results indicate the reduction in the breakdown strength of the epoxy resin with the increase in frequency and temperature. Furthermore, the effects of temperature (up to 120 °C) on breakdown strength were no more obvious than those of frequency (up to 8 kHz). That is mainly derived from the glass transition of epoxy resin. Through discussing the dielectric loss and energy dissipation by FEM simulations together with the complex permittivity of epoxy resin, it could be concluded that the dielectric heating contributes to the acceleration of electric breakdown under high-frequency voltages. In addition to the fundamental frequencies, the harmonic voltages introduced high electric stresses and dielectric loss, resulting in a decrease in breakdown strength. The dielectric heating related to the electric stresses and frequencies should be considered in the insulation design of MF-HF transformers.

Exploring argon plasma effect on ferroelectric Hf0.5Zr0.5O2 thin film atomic layer deposition

The doped/alloyed HfO2 and ZrO2 thin films revolutionized not only the field of ferroelectric physics but also various ranges of device applications. Especially when the two oxides are combined in an 1:1 ratio, the ferroelectric polarization of the material became the most distinctive. Many researchers have investigated various different process conditions such as controlling Hf0.5Zr0.5O2 (HZO) film thickness and modifying different metal electrodes. Here, we explored the effect of additional Ar plasma treatment to the HZO film. The additional Ar plasma was exposed to the plasma-enhanced atomic layer deposition (PEALD) HZO for this study. Then, the sample was compared with a conventional PEALD and thermal ALD HZO films. By understanding the polarization–electric field (P–E), current–electric field (I–E), and electrical breakdown characteristics of the different samples, it was found that the Ar plasma treatment can control the degree of ferroelectric and antiferroelectric phases of HZO film.