Low Breakdown Voltage Research Articles

The Simulation of Dielectric Barrier Discharge for Breakdown Voltage in Starch Modification

This paper presents the simulation results for dielectric barrier discharge (DBD) at atmospheric pressure in argon gas for different relative permittivity, granule shape, thickness layer, and granule diameter measurements for starch on the breakdown voltage. DBD is commonly utilized to generate cold plasma for starch modification. The electric field was computed using COMSOL Multiphysics 5.3a software. The breakdown voltage was calculated employing Paschen’s law for this electric field. The voltage was found according to the breakdown criterion for gap distance 0.2–1.0 cm, and then the Paschen curve could be plotted. The results show that the top electrode of the plasma system may be replaced with the parallel plate electrode by a mesh electrode with a bigger mesh size to achieve a lower breakdown voltage. In addition, increasing the relative permittivity and decreasing the thickness layer can reduce the applied voltage for plasma formation. When compared to the sphere and ellipsoid shapes, starch with a polyhedral granule shape requires a significantly lower voltage for breakdown. The starch granule diameter does not affect the breakdown voltage. These findings can be utilized to determine the optimal breakdown voltage for each type of starch modification, contributing to the construction of a high-efficiency plasma production system for starch modification.

Large-Scale β-Ga2O3 Trench MOS-Type Schottky Barrier Diodes with 1.02 Ideality Factor and 0.72 V Turn-On Voltage

β-Ga2O3 Schottky barrier diodes (SBDs) suffer from the electric field crowding and barrier height lowering effect, resulting in a low breakdown voltage (BV) and high reverse leakage current. Here, we developed β-Ga2O3 trench MOS-type Schottky barrier diodes (TMSBDs) on β-Ga2O3 single-crystal substrates with halide vapor phase epitaxial layers based on ultraviolet lithography and dry etching. The 1/C2−V plots are deflected at 2.24 V, which is caused by the complete depletion in the mesa region of the TMSBDs. A close-to-unity ideality factor of 1.02 and a low turn-on voltage of 0.72 V are obtained. This is due to the low interface trap density in the metal/semiconductor interface of TMSBDs, as confirmed by the current–voltage (I–V) hysteresis measurements. The specific on-resistance calculated with the actual Schottky contact area increases as the area ratio (AR) increases because of the current spreading phenomenon. Furthermore, the reverse leakage current of the TMSBDs is smaller and the BV is increased by 120 V compared with the regular SBD. This work paves the way for further improving the overall performance of β-Ga2O3 TMSBDs.

Molecular ionization potentials of triglycerides and mechanism analysis of streamer discharge in vegetable insulating oil

With the enhancement of social awareness of environmental protection, scholars have gradually began to focus their research on vegetable-oil-based insulating fluid. In this work, we calculated the ionization potential of triglyceride molecules in vegetable oil (VO), analyzed the mechanism of charge generation, and explained the cause of fast streamer discharge in VO based on the distribution characteristics of ionization potential. Some interesting results were obtained. The position of CC on the triglyceride branch chain can affect the ionization potential of triglycerides. Specially, the CC at the Sn-2 position can significantly reduce the ionization potential of glycerol molecules. The ionization of unsaturated triglycerides is mainly caused by the electron loss of carbon atoms in the CC double bond; the formation of negative ions mainly rely on ester groups and their nearby atoms to capture electrons. In VO, low ionization potential molecules are predominantly present, and their presence results in a lower breakdown voltage and easy formation of the fast streamer discharge. We anticipate that our research can provide theoretical support for the application research of vegetable insulating fluid.

Dynamic Variation of Rectification Observed in Supramolecular Mixed Mercaptoalkanoic Acid.

Functionality in molecular electronics relies on inclusion of molecular orbital energy level within a transmission window. This can be achieved by designing the active molecule with accessible energy levels or by widening the window. While many studies have adopted the first approach, the latter is challenging because defects in the active molecular component cause low breakdown voltages. Here, it is shown that control over the packing structure of monolayer via supramolecular mixing transforms an inert molecule into a highly tunable rectifier. Binary mixed monolayer composed of alkanethiolates with and without carboxylic acid head group as a proof of concept is formed via a surface-exchange reaction. The monolayer withstands high voltages up to |4.5 V| and shows a dynamic rectification-external bias relationship in magnitude and polarity. Sub-highest occupied molecular orbital (HOMO) levels activated by the widened transmission window account for these observations. This work demonstrates that simple supramolecular mixing can imbue new electrical properties in electro-inactive organic molecules.

Microplasma Illumination Enhancement in N+P‐Co‐Ion‐Implanted Nanocrystalline Diamond Films

N‐ and P‐co‐ion implantation enhances the electrical conductivity of nanocrystalline diamond films to 6.9 s cm−1 and improves the microplasma illumination (MI) characteristics of the films to a low breakdown voltage of 340 V, large plasma current density of 6.3 mA cm−2 (@510 V) with plasma life‐time stability of 10 h. N ions induce nanographitic phases in the films and P ions lower the resistance at the diamond‐to‐Si interface together promoting the conducting channels for effective electron transport, consequently attaining the improved MI properties of the films.

Simultaneous hydrodynamic cavitation and nanosecond pulse discharge plasma enhanced by oxygen injection

A novel Hydrodynamic Cavitation-Assisted Oxygen Plasma (HCAOP) process, which employs a venturi tube and oxygen injection, has been developed for enhancing the production and utilization of hydroxyl radicals (·OH) in the degradation of organic pollutants. This study has systematically investigated the fluid characteristics and discharge properties of the gas–liquid two-phase body in the venturi tube. The hydraulic cavitation two-phase body discharge is initiated by the bridging of the cavitation cloud between the electrodes. The discharge mode transitions from diffuse to spark to corona as the oxygen flow rate increases. The spark discharge has the highest current and discharge energy. Excessive oxygen results in the change of the flow from bubbly to annular and a subsequent decrease in discharge energy. The effects of cavitation intensity, oxygen flow rate, and power polarity on discharge characteristics and ·OH production were evaluated using terephthalic acid as a fluorescent probe. It was found that injecting 3 standard liter per minute (SLPM) of oxygen increased the ·OH yield by 6 times with only 1.2 times increase in power, whereas<0.5 SLPM of oxygen did not improve the ·OH yield due to lower breakdown voltage. Negative polarity voltage increased the breakdown voltage and ·OH yield due to asymmetric density and pressure distribution in the throat tube. This polarity effect was explained by numerical simulation. Using indigo carmine (E132) as a model pollutant, the HCAOP process degraded 20 mg/L of dye in 5 L water within 2 min following a first-order reaction. The lowest electric energy per order (EEO) was 0.26 (kWh/m3/order). The HCAOP process is a highly efficient flow-type advanced oxidation process with potential industrial applications.

Pre-Breakdown and Breakdown Phenomena in Liquid Nitrogen With a Tape–Plane Electrode Geometry

Pre-breakdown and breakdown phenomena are investigated in liquid Nitrogen (LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) with a tape-plane electrode geometry. Different voltage waveforms are used: lightning and switching standard impulses, step impulse, and DC ramp. The influence of temperature is also investigated, by sub-cooling LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> down to 65 K. Breakdown voltage depends on polarity, gap distance, temperature, and HV waveform: the longer waveform, the lower breakdown voltage. Positive pre-breakdown streamers are about 3 decades faster than negative ones. With short duration lightning impulses, the propagation of slow negative streamers is quenched, resulting in higher breakdown voltage. In boiling conditions, slow negative streamers may propagate for long durations. Sub-cooling LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> induces a slight increase of streamer initiation voltage, and impedes the propagation of slow streamers due to condensation.

Modelling and analysis of electrical performance outdoor glass insulator under various services and lightning impulse

This paper is focus on modelling of glass type insulator with voltage rating of 275 kV. The glass insulators are still widely served in overhead transmission line because of its high dielectric strength capability. However, their outdoor application has resulted in the exposure to the various service conditions such as weather, pollution and lightning conditions. Further, the inclination effect of the insulator under the nominal voltage and lightning impulse is modelling through Finite Elementary Method (FEM). Then, the model of glass insulator is constructed in three different inclination angles by using the Ansys Maxwell 3D for simulation purpose. The results show the inclined insulator due to the wind load effect has the lowest breakdown voltage at most 53.33% compared with the vertical insulator. Under the outdoor environment factors such as humid, wet and contamination, the localized electric field and current density had increased significantly. Consequently, this situation may cause the power losses, localized heating effect also reduces the electrical performance of the insulators.

Ignition detection with the breakdown voltage measurement during nanosecond repetitively pulsed discharges

Nanosecond Repetitively Pulsed Discharge (NRPD) is a promising ignition concept for introducing diesel-like process parameters for hard-to-ignite renewable fuels in Spark Ignition (SI) engines. Knowing whether an ignition event initiated by a series of nanosecond electrical discharges was successful or not gives the possibility of using this information for closed-loop ignition control. This paper presents a methodology for detecting successful ignition under NRPD ignition.After a nanosecond discharge, the heat loss from the particles (plasma-gas) between the electrodes and the surrounding gas is different if a robust flame kernel is established. If a flame kernel is present, the heat losses are lower, resulting in a lower local density of the gas between the electrodes. The breakdown voltage value of a nanosecond pulse is proportional to the local density. A control pulse is applied after the main ignition sequence to detect successful ignition. Lower breakdown voltages of the control pulse are present if a robust early flame kernel is present. The control pulse is applied before the pressure rises due to the presence of fast combustion, allowing ignition to be detected during the inflammation phase, thus allowing the possibility to place additional ignition events, if necessary.This technique was experimentally analyzed in a Constant Volume ignition Cell (CVC) and in a Rapid Compression Expansion Machine (RCEM). In the CVC at the ignitability limit, lower breakdown voltages of the control pulse are mostly measured when no pressure rise is measured. In the RCEM, the heat release rate is analyzed with a two-zone thermodynamic model, and the early flame kernel formation is monitored with Schlieren imaging. Some overlap exists in the control pulses' breakdown voltages for the ignition and quenching experiments; nevertheless, the Schlieren videos outline that the overlapping cases have a similar flame kernel formation, and the difference arises thereafter.

Structure and Electric Properties of Anodized Aluminum with PEDOT:PSS Conductive Polymer Cathode

Aluminum solid electrolytic capacitors using a conductive polymer as a cathode material has the advantages of low equivalent series resistance (ESR) and high thermal stability compared to aluminum electrolytic capacitors using liquid electrolytes. A disadvantage of aluminum solid electrolytic capacitors with a conductive polymer is the low breakdown voltages, limiting the operating voltage of the capacitors to ∼100 V or less. In this study, for a possible future increment of the withstand voltages of solid electrolytic capacitors, PEDOT:PSS-coated aluminum with an amorphous or crystalline alumina layer formed at 500 V has been characterized using SEM, STEM/EDS, and conductive AFM to understand the distribution of PEDOT:PSS conductive polymer and its influence on the electric properties. The crystalline alumina layer, developed beneath a porous hydrated alumina layer, contains many voids, which increase the leakage current compared to the void-less amorphous alumina layer. However, the crystalline alumina layer with PEDOT:PSS exhibits a higher breakdown voltage than the amorphous one. The limited incorporation of PEDOT:PSS into the inner part of the porous hydrated alumina layer may introduce a resistive surface layer, possibly contributing to the increased dielectric breakdown.

Prebreakdown and Breakdown Phenomena in HFO Gas Under Impulse Voltage—Part I: Divergent Field

Pre-breakdown and breakdown phenomena in HFO1234ze(E) gas are studied with a wide range of electrode geometries, characterized by a field enhancement factor η ranging from 1.7 (quasi uniform field) to 90 (very divergent field). As in SF6, breakdown in HFO results from the inception and propagation of leaders. Depending on the field geometry, the measured breakdown voltage represents either the voltage required for leader complete propagation (in divergent field, η > 10), or for inception (in quasi-uniform field, η < 10). This paper mostly concerns results obtained with divergent fields. Leader propagation in HFO is barely influenced by pressure, and the minimum voltage required for propagation to breakdown is slightly lower compared to SF6, explaining that lower breakdown voltages are recorded with HFO in divergent field. In such conditions, breakdown voltage is mainly determined by the gap distance. HFO degradation, evidenced by the formation of black soot after breakdown, has no influence on leader propagation, and hence on breakdown properties in divergent fields.

Synthesis of Methyl Ester from Waste Cooking Oil Toward Application in Transformer’s Insulating Liquid

This study evaluated the feasibility of using methyl ester prepared from waste cooking oil for electrical insulation in distribution transformers. Methyl ester is produced by a transesterification reaction between waste cooking oil and methanol using sodium hydroxide as a catalyst. The physicochemical parameters and breakdown voltage of the methyl ester were determined. The effects of ageing on breakdown voltage, viscosity and acid value of methyl ester were also investigated. In addition, the breakdown voltage of Kraft paper impregnated with methyl ester was determined. Experimental results showed that methyl ester from waste cooking oil had low viscosity (5.17 cSt) and high breakdown voltage (40.3 kV). Other parameters also meet ASTM D6871 except for the pour and flash points. Ageing insignificantly affected the breakdown voltage of the methyl ester. After ageing, the breakdown voltage of the methyl ester increased to 42.1 kV. However, the viscosity of the methyl ester also increased by 23.5% and the acid value increased by 79.2 times. Finally, the breakdown voltage of Kraft paper impregnated with the methyl ester was about 5-10% lower than that of paper impregnated with the mineral oil.

Effect of co-doping Nb2O5 with equal amount of Eu2O3 or In2O3 on the electrical properties of TiO2-based varistors

In this work, TiO2 varistors with enhanced nonlinear coefficient, low breakdown voltage, high relative dielectric constant and low dielectric loss were fabricated by co-doping of Nb2O5 with equal amount of Eu2O3 or In2O3. The results indicated an appropriate proportion of dopant could improve the comprehensive performance of the varistors. For the TiO2–Nb2O5–Eu2O3 system, the breakdown voltage and relative dielectric constant of the samples decreased first and then increased, while the nonlinear coefficient increased first and then decreased with the increase of doping content, the best value appears at the doping content of 1.00 mol% (E1mA = 2.14 V/mm, α = 4.6, εr = 2.72 × 105, tanδ = 0.25). It is noted that the secondary phase formed on the grain boundary as Eu2Ti2O7, thus the growth of grain was hindered and the dielectric performances deteriorated. By contrast, for the TiO2–Nb2O5–In2O3 system, the secondary phase was not found. As a result, a low breakdown voltage, low dielectric loss and high nonlinear coefficient were obtained, reaching the best at the doping content of 5.0 mol% (E1mA = 4.6 V/mm, α = 8.4, εr = 1.85 × 105, tanδ = 0.16). The influence of this doping system on the electrical performance can be explained by Internal Barrier Layer Capacitance theory (IBLC), which is related to the potential barrier at the grain boundary.

Design and Fabrication of High-Efficiency, Low-Power, and Low-Leakage Si-Avalanche Photodiodes for Low-Light Sensing.

Since the advent of impact ionization and its application in avalanche photodiodes (APD), numerous application goals have contributed to steady improvements over several decades. The characteristic high operating voltages and the need for thick absorber layers (π-layers) in the Si-APDs pose complicated design and operational challenges in complementary metal oxide semiconductor integration of APDs. In this work, we have designed a sub-10 V operable Si-APD and epitaxially grown the stack on a semiconductor-on-insulator substrate with a submicron thin π-layer, and we fabricated the devices with integrated photon-trapping microholes (PTMH) to enhance photon absorption. The fabricated APDs show a substantially low prebreakdown leakage current density of ∼50 nA/mm2. The devices exhibit a consistent ∼8.0 V breakdown voltage with a multiplication gain of 296.2 under 850 nm illumination wavelength. We report a ∼5× increase in the EQE at 850 nm by introducing the PTMH into the device. The enhancement in the EQE is evenly distributed across the entire wavelength range (640-1100 nm). The EQE of the devices without PTMH (flat devices) undergo a notable oscillation caused by the resonance at specific wavelengths and show a strong dependency on the angle of incidence. This characteristic dependency is significantly circumvented by introducing the PTMH into the APD. The devices exhibit a significantly low off-state power consumption of 0.41 μW/mm2 and stand fairly well against the state-of-the-art literature. Such high efficiency, low leakage, low breakdown voltage, and extremely low-power Si-APD can be easily incorporated into the existing CMOS foundry line and enable on-chip, high-speed, and low-photon count detection on a large scale.

Monte Carlo Simulation of Alkaline Earth Metal Oxides Protective Layers Bombarded With Ne+ or Xe+ in Plasma Display Panels

One of the major components of commercial plasma display panel (PDP) cells is the magnesium oxide (MgO) protective layer. In order to obtain both lower discharge breakdown voltage and higher energy efficiency in the cells, other alkaline Earth metal oxides have been extensively studied as alternatives to MgO. Another important factor in the life-extending of PDP is resistance to ion sputtering. In this article, the Monte Carlo simulation program Stopping and Range of Ions in Matter (SRIM)-2013 was applied to study the behavior of the sputtering yield, vacancies/ions, backscattered ions, ion range, lateral and radial projection, energy loss due to ionization, vacancies, and phonons, of MgO, calcium oxide (CaO), SrO, and barium oxide (BaO) as a function of incident angle for Ne <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{+}$ </tex-math></inline-formula> and Xe <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{+}$ </tex-math></inline-formula> ion beam. It is discovered that CaO, SrO, and BaO protective layers increase the number of backscattered ions from surfaces when they are hit by noble gas ions. They resist sputtering and vacancies better than the MgO protective layer.

Spray coagulation as an alternative to argon plasma coagulation for bleeding portal hypertensive gastropathy

Spray coagulation as an alternative to argon plasma coagulation for bleeding portal hypertensive gastropathy

The effect of DRIE notching on field emission enhanced breakdown in SOI based MEMS electrodes

Microscale (<5 μm) gas breakdown is usually dominated by field emission, which is influenced largely by electrode surface morphology. At present, there is a large number of studies on the breakdown and discharge of different metal electrode geometry and electrode spacing as well as micro-electro-mechanical system (MEMS) device structures, but few studies on the breakdown of MEMS electrodes affected by notching, which will greatly change the electrode surface morphology but is difficult to completely avoid in deep reactive ion etching process based on silicon on insulator (SOI) wafer. In response to this situation, this paper conducted breakdown tests and field emission tests on MEMS samples with and without notching. It was found that samples with notching could withstand more breakdowns of about 6–13 times before the formation of internal resistance, increased by 200%–300% compared with samples without notching, and have a lower breakdown voltage of about 210 V, 16% lower than that of samples without notching. In addition, it was also found that for the samples with notching, the field enhancement factor gradually decreases with the increase of the number of breakdown events. When the field enhancement factor decreases to about 100, the subsequent breakdown is highly likely to cause the sample to form electrical connection, thus completely damaging the sample. Above conclusions have certain reference value for designing the actuation voltage of MEMS devices based on SOI wafers.

Impact of surface charges on energy deposition in surface dielectric barrier discharge: a modeling investigation

Surface charges have significant impact on the evolution of surface dielectric barrier discharge (SDBD). In this work, the role of residual surface charges on repetitively nanosecond pulsed SDBD in atmospheric air is investigated using a two-dimensional fluid model, based on the assumption of preserving the distribution of surface charges at the end of the previous high voltage (HV) pulse. In the bipolar mode when the polarity of residual surface charges is opposite to that of the current HV pulse, a lower breakdown voltage and more deposited energy can be observed, showing an obvious enhancement of SDBD. In the unipolar mode, residual surface charges suppress the development of discharges and energy deposition. It is found that more residual surface charges are accumulated during the negative pulsed discharge, which have a more pronounced effect on the subsequent positive pulsed one. This is explained by the fact that the negative surface streamers directly contact the dielectric and charge it, while the positive surface streamers float above the dielectric, forming a ion-rich region near the surface. The results in this work demonstrate the mechanism of how residual surface charges affect discharge dynamics, which can be utilized to regulate energy deposition in SDBDs.

The possibility of gallium oxide (β-Ga2O3) heterojunction bipolar transistors

Bipolar junction transistors have not been viable with β-Ga2O3 due to its poor hole mobility and unavailability of shallow acceptors. Many p-type oxides form high-quality heterojunction diodes (low ideality factor and high breakdown voltage) with β-Ga2O3. We propose using these heterojunctions to make a β-Ga2O3 heterojunction bipolar transistor (HBT). Cu2O/β-Ga2O3 heterojunction is especially promising because of the relatively high electron diffusion length (∼μ m) in Cu2O, a low electron injection barrier at the Cu2O-Ga2O3 interface, and breakdown voltages of >1000 V. Using Silvaco TCAD, we simulate a β-Ga2O3 heterojunction bipolar transistor with a Cu2O base and estimate the power figure of merit (PFOM). We find that the low bandgap of Cu2O severely limits the performance of these HBTs. Reports of Cu2O-Ga2O3 diodes with extremely high breakdown voltage are probably due to heavily doped Cu2O or interface defects, but these effects do not translate to the HBT. For HBTs with PFOM better than the state-of-the-art β-Ga2O3 unipolar transistors, we need alternative p-type oxides with a bandgap E g > 3.4 eV and electron diffusion length >0.4 μ m. We discuss the possible candidates. Using an empirical model for the critical avalanche breakdown field, we estimate the maximum PFOM for possible β-Ga2O3 HBTs.

Coaxial Low-Pass Filter Design and Manufacture

In this study, a low-pass filter with coaxial transmission lines is designed and produced. The objective for designing a coaxial low-pass filter was to utilize both low loss transmission and high breakdown voltage capability for high power microwave applications to enable the suppression of the second harmonic of the 4.4-6 GHz C-Band ( C-Band was selected as a proof of concept ) signals with minimal insertion loss. Microwave and 3D electromagnetic simulators were used in the filter design. The design was started by establishing an 11 th order Chebyshev low-pass filter prototype giving 0.05 dB ripple. Based on this prototype, a filter circuit consisting of capacitors and inductors as lumped elements was designed. The low and high impedances to be selected for the stepped impedance method, which is the basis of the transition to coaxial transmission lines, were decided and the most suitable impedances for manufacturing was determined. The filter using these impedances and designed with stepped impedance lines was transformed into the filter in which coaxial transmission lines are used. Coaxial transmission lines in the low-pass filter circuit consist of conductors with an insulating material in between. While the insulating material is selected as air in the high impedance sections of the transmission lines, it is PTFE (Polytetrafluoroethylene) with an insulating constant of 2.1 in the low impedance sections. The designed filter was manufactured. The basic properties of the manufactured filter were characterized by using RF measuring devices and compared with the designed filter. The measurements results prove that the frequency responses of the designed filter and the produced filter are very close to each other. Namely, a low-pass filter with a cutoff frequency of 6 GHz, a sharp suppression of about 45 dB at the stopband of 9 GHz and a return loss of 20 dB was designed and produced by using coaxial transmission lines. The novelty in our work can be stated that the power handling capability is increased by two techniques. The first one is that the highest transmission line radius preventing the higher order mode excitations is used to decrease the conductor loss. Teflon is covered around the low impedance lines to enhance the dielectric breakdown capability. Teflon inclusion is also used to decrease the practical low impedance level that improves the filter characteristics.