Breakdown Field Research Articles

Enhanced Energy Storage Properties for Bi(Ni0.5Hf0.5)O3 doped KNN Ceramics

Abstract In this work, (1-x)K0.5Na0.5NbO3-xBi(Ni0.5Hf0.5)O3 (x = 0.15, 0.17, 0.2, 0.25) [abbreviated by (1-x) KNN-xBNH] lead-free energy storage ceramics were prepared by the conventional solid-phase reaction method. The results indicate that BNH has been successfully incorporated into the KNN lattice, forming a homogeneous and stable solid solution. At the A site, hybridization between Bi 6p and O 2p orbitals can ameliorate the polarity, inducing an increase in Pmax. At the B site, Nb5+ is substituted by (Ni0.5Hf0.5)3+, leveraging differences in oxidation states and ionic radii to enhance the relaxation behavior. Moreover, the addition of BNH effectively refines grain size and optimizes breakdown field strength. At x = 0.17, the ceramics achieve optimal energy storage performance, with Wtot = 1.375 J/cm³, Wrec = 1.071 J/cm³, and η = 77.89%(~184 kV/cm).

Estimating the Electric Fields Driving Lightning Dart Leader Development With BIMAP‐3D Observations

AbstractIn this paper, a numerical dart leader model has been implemented to understand the leader's development and the corresponding electric field changes observed by the 3D broadband mapping and polarization (BIMAP‐3D) system. The model assumes the extending leader channel is equipotential and has a linear charge distribution induced by an ambient electric field. The charge distribution induced by the ambient field can be used to model the electric field change at the ground. We then find the ambient electric field which best fits the field change measurements at the two BIMAP stations. The estimated ambient electric field decreases in the direction of dart leader propagation. Our observations and modeling results are consistent with our earlier hypothesis that dart leader speed is proportional to the electric field at the leader tip. The model also supports our earlier analysis that leader speed variations near branch junctions were due to previous charge deposits near the junctions. The modeled tip electric field is generally lower than the breakdown field unless the pre‐dart‐leader channel has a significant temperature of 3,000 K. This is consistent with the fact that dart leaders typically do not form new branches into the virgin air. Furthermore, the tip field is generally close to the negative streamer stability field at ambient temperatures, explaining the nature of the narrow and well‐defined channel structure. In addition to the charge distribution and the ambient and tip electric field, the development of the channel potential and current distribution are also presented.

A gallium oxide MESFET transistor with potential barrier layers for high-power and high-frequency applications

Abstract In this article, a novel gallium oxide metal semiconductor field effect transistor (MESFET) is presented. This device is designed for high-power and high-frequency usage and features embedded potential barrier layers on each side of the gate metal within the channel. The gallium oxide semiconductor (Ga2O3) is highly valued in semiconductor technologies because of its large band gap (4.9–4.8 eV) and high breakdown field (6–8 MV cm−1). These properties make it suitable for high-power and high-frequency operations. We call the proposed structure; the potential barrier layers in Gallium Oxide MESFET (PBL-GO-MESFET). The key idea in the PBL-GO-MESFET transistor is embedding the PB layers to control the electric field distribution. Because of the PB layers, an increased breakdown voltage is observed in the PBL-GO-MESFET device, which is in contrast to conventional GO-MESFET (C-GO-MESFET) devices. The simulation findings indicate that the PBL-GO-MESFET transistor surpasses the C-GO-MESFET transistor in terms of breakdown voltage and radio frequency (RF) traits.

Inkjet printing of sustainable ZTO/AlOx thin film transistors

Abstract Even though printed metal oxide thin film transistors (TFTs) have been a central topic of research in the past decade, the most notable results still require scarce elements such as gallium and indium, or high annealing temperatures (≥ 400 °C) when used non-critical raw materials such as zinc and tin.
In this work, safe, abundant and inexpensive materials such as zinc, tin and aluminum are explored to reach low-cost thin films and devices with both the semiconductor and dielectric layers deposited by inkjet printing and annealed at lower temperatures (300 °C). Alumina (AlOx) and zinc tin oxide (ZTO) inks containing a theoretical optimal V% of ethylene glycol (EG) were optimized for production of uniform and reproducible AlOx/ZTO thin film layers. Common ink parameters (such as the reverse Ohnesorge, capillary, Webber and Reynolds numbers) were evaluated and compared with relevant literature on inkjet drop formation mechanisms. Inks within theoretical optimal parameter values were printing optimized in terms of drops per inch, number of layers, UV substrate surface activation, print speed, and post annealing. A high-quality dielectric of two alumina layers was printed, having a breakdown field above 2.93 ± 0.33 MV.cm-1, and a dielectric constant of 7.74 ± 0.73 at 1 kHz. Thin film transistors (TFTs) of inkjet printed (IJP) ZTO/AlOx layers were produced with a maximum IOn/IOff ratio of 103 and a saturation mobility of 2.2 cm2.V-1.s‑1. This approach not only advances the field of printed electronics but also addresses concerns related to material scarcity, thermal budget, and production costs.

Оксид галію — перспективний мультифункціональний матеріал четвертого покоління (огляд)

This work is devoted to the analysis and systematization of the main information on the properties of gallium oxide and materials based on it and their practical application, as well as the prospects for further research of the specified actual oxide material. A review of literature data concerns general properties and structure of gallium oxide Ga2O3, various methods to produce Ga2O3 thin films, nanostructures, bulk crystals, powders, the application of gallium oxide in various fields of science and technology, including semiconductor field, electronic engineering, optoelectronics, the creation of composite transparent materials, etc. In the last thirty years or so, thanks to the progress in growing large-volume, high-quality gallium oxide crystals, this material with an ultra-wide band gap and a high critical breakdown field has gained significant application in the manufacture of the latest power electronics and high-voltage electronic devices. Important experimental studies, in particular, in terms of developing methods of metallization, joining similar materials, connecting electrical contacts, for example, by soldering, require the study of the wetting of these oxide materials by metal melts and the contact interaction at the interphase boundaries. Data on surface phenomena, in particular the wetting of gallium oxide by metals, are practically absent in the literature, and this requires further additional research. Keywords: gallium oxide, physical properties, semiconductor, power electronics, optoelectronics, transparent composite materials.

High dielectric energy storage properties of chitin matrix composites regulated by SiO2.

High-performance polymer-based dielectric materials have attracted much attention in the field of energy storage due to high breakdown field strength and low cost. However, partial polymer-based materials are derived from traditional fossil energy derivatives, which are characterized by non-renewable and low dielectric constants, which are not conducive to the improvement of energy storage. In this paper, dissolved chitin through alkali/urea system is composited with SiO2 prepared by electrostatic spinning. The maximum discharge energy density of the fiber composite film reaches 4.34 J cm-3, which is 1.6 times higher than that of the micron particle composite film (2.8 J cm-3) and 1.9 times higher than that of the pure chitin film. The high aspect ratio and low concentration of silica filler effectively improved the breakdown field strength. In addition, the thermal stability was improved. This study paves the way for the application of bio-based materials in high-performance dielectrics.

750 V Breakdown in GaN Buffer on 200 mm SOI Substrates Using Reverse-Stepped Superlattice Layers

In this work, we demonstrated the epitaxial growth of a gallium nitride (GaN) buffer structure on 200 mm SOI (silicon-on-insulator) substrates. This epitaxial layer is grown using a reversed stepped superlattice buffer (RSSL), which is composed of two superlattice (SL) layers with different Al component ratios stacked in reverse order. The upper layer, with a higher Al component ratio, introduces tensile stress instead of accumulative compressive stress and reduces the in situ curvature of the wafer, thereby achieving a well-controlled wafer bow ≤ ±50 µm for a 3.3 µm thick buffer. Thanks to the compliant SOI substrate, good crystal quality of the grown GaN layers was obtained, and a breakdown voltage of 750 V for a 3.3 µm thick GaN buffer was achieved. The breakdown field strength of the epitaxial GaN buffer layer on the SOI substrate is estimated to be ~2.27 MV/cm, which is higher than the breakdown field strength of the GaN-on-Si epitaxial buffer layer. This RSSL buffer also demonstrated a low buffer dispersion of less than 10%, which is good enough for the further processing of device and circuit fabrication. A D-mode GaN HEMT was fabricated on this RSSL buffer, which showed a good on/off ratio of ~109 and a breakdown voltage of 450 V.

Improved leakage and fatigue properties of W/Hf0.5Zr0.5O2/W capacitor through the insertion of Pt metallic layer

The successful integration of Hf0.5Zr0.5O2 (HZO) ferroelectric (FE) thin film into memory devices necessitates addressing the challenges associated with achieving high remanent polarization (Pr) and low leakage current, in order to ensure excellent reliability. The limitations of HZO film are overcome in this paper through the design of a Pt/W bilayer electrode, wherein a thin Pt metallic layer (ML) is embedded at the top interface of the W/HZO/W capacitor. This innovative approach combines the unique advantages offered by both W and Pt electrodes. The results reveal that the 2Pr values of the W/HZO/5 Pt/W and W/HZO/10 Pt/W capacitors, with Pt ML thicknesses of 5 nm and 10 nm, respectively, are slightly lower at 42.1 μC/cm2 and 35.9 μC/cm2 compared to the reference W/HZO/W capacitor's value of 47.9 μC/cm2. This notwithstanding, these 2Pr values still maintain comparability with previously reported findings. Moreover, compared to the reference W/HZO/W capacitor, the W/HZO/10 Pt/W capacitor exhibits a reduction of one order of magnitude in leakage current, a 30 % increase in breakdown field from 3.0 MV/cm to 3.9 MV/cm, and an improvement of one order of magnitude in endurance performance, reaching 1.3 × 108 cycles. This improvement can be attributed to the incorporation of a thin Pt ML, which enhances the schottky barrier and prevents potential oxidation of adjacent W electrode near the HZO film, effectively alleviating the leakage current. The present work demonstrates the successful mitigation of leakage current and improved fatigue properties while preserving FE characteristics through strategic insertion of Pt ML. The research findings can offer valuable scientific guidance for optimizing the performance of HZO-based devices.

Effects of Pulsed Electric Fields on the Elimination of Fusarium oxysporum in Greenhouse Soil

In greenhouses, high humidity, low light, and inadequate ventilation conditions, along with continuous and high-density planting, promote the proliferation of soilborne pathogens. Among these pathogens, Fusarium oxysporum Schltdl (F. oxysporum) is a notably challenging one, causing root rot of tomato plants in greenhouse cultivation. To address this issue, this study applied a pulsed electric field (PEF) to target the elimination of F. oxysporum in suspension and soil media. Initially, PEF parameters were systematically explored in suspensions to determine the effective ranges for the elimination of F. oxysporum. The results revealed that the effective ranges for achieving the desired microbial reduction were an electric field strength (EFS) between 5–15 kV·cm−1, a pulse number within the range of 100–500, and a pulse width of 10–20 µs. Subsequently, the impact of soil moisture content, soil bulk density, and soil type on soil dielectric breakdown field strength was analyzed within the range from previous results. Based on these findings, the soil experiments were conducted with parameters designed to prevent dielectric breakdown. Specifically, for sampling soil with a moisture content of 16.2% and a bulk density of 1.31 g·cm−3, the maximum effective application of electric field strength was 9.5 kV·cm−1, accompanied by 1000 pulses and a pulse width of 20 µs. Finally, building on these results, soil samples were sterilized within a parameter range that spanned an electric field strength of 5–9.5 kV·cm−1, a pulse number between 100–500, and a pulse width of 10–20 µs. Response surface methodology (RSM) analysis further identified the optimal parameter combination: an electric field strength of 8.2 kV·cm−1, 306 pulses, and a pulse width of 15 µs, resulting in an average lethal rate of 76.16% for F. oxysporum sterilization in soil. These findings suggest the potential use of PEF against F. oxysporum and other pathogens in greenhouse soils, and provide theoretical foundations for further experiments, thereby contributing to the sustainable advancement of greenhouse agriculture.

Dielectric high gradient insulator – Progress towards multilayer insulating structures

High gradient insulators (HGI) consisting of ceramic and metallic alternating layer structure, have been shown to reduce surface breakdown occurrence in high voltage devices. Recently, the HGI's metal layers were replaced with high dielectric constant ceramics, creating dielectric high gradient insulators (DHGI) that were shown to outperform pure alumina analog. A 2-layer DHGI prototype manufactured by spark plasma sintering (SPS) demonstrated an increased surface breakdown field and fewer surface breakdowns during conditioning, compared to plain alumina. However, weak breakdowns at the opposite polarity were observed in the 2-layer structure. This study focuses on overcoming this issue by introducing a 3-layer design, with two high dielectric layers capping a plain alumina layer. Breakdown tests confirmed the elimination of weak breakdowns and improved dielectric strength, consistent with simulations predictions. Additionally, post-SPS air annealing was shown to be essential for removing adsorbed gases and recovering the high dielectric layers composition that changed during SPS. The annealed DHGIs were shown to reduce significantly the breakdown pulses during high-voltage conditioning. The 3-layer DHGI exhibited a 33.5 % higher breakdown field than plain alumina and a 13.5 % improvement over the 2-layer DHGI reported earlier.

(Invited) Ultrathin Polymer Insulating Layers By Initiated Chemical Vapor Deposition for Low-Power Soft Electronics

Insulating layers based on oxides and nitrides provide high capacitance, low leakage, high breakdown field and resistance to electrical stresses when used in electronic devices based on rigid substrates. However, their typically high process temperatures and brittleness make it difficult to achieve similar performance in flexible or organic electronics. Here, we show that poly(1,3,5-trimethyl-1,3,5-trivinyl cyclotrisiloxane) (pV3D3) prepared via a one-step, solvent-free technique called initiated chemical vapour deposition (iCVD) is a versatile polymeric insulating layer that meets a wide range of requirements for next-generation electronic devices. Highly uniform and pure ultrathin films of pV3D3 with excellent insulating properties, a large energy gap (>8 eV), tunnelling-limited leakage characteristics and resistance to a tensile strain of up to 4% are demonstrated. The low process temperature, surface-growth character, and solvent-free nature of the iCVD process enable pV3D3 to be grown conformally on plastic substrates to yield flexible field-effect transistors as well as on a variety of channel layers, including organics, oxides, and graphene. In this presentation, we will review the advantageous characteristics of iCVD gate dielectric layers for soft electronics and their various device applications.

Temperature-Dependent Ferroelectric Behaviors of AlScN-Based Ferroelectric Capacitors with a Thin HfO2 Interlayer for Improved Endurance and Leakage Current

The ferroelectric switching behavior of a metal–ferroelectric AlScN–HfO2 interlayer–metal (MFIM) capacitor was investigated at variable temperatures and compared with an MFM capacitor. Although the MFIM capacitor demonstrated an inferior remnant polarization (2Pr value of 74 µC/cm2), it exhibited a reduced leakage current (×1/100) and higher breakdown field. The MFIM showed a stable change in 2Pr from room temperature to 200 °C and an enhanced endurance of ~104 cycles at 200 °C; moreover, the leakage current was less degraded after the cycling tests. Thus, the ferroelectric AlScN with a thin HfO2 interlayer can enhance the reliability of ferroelectric switching.

Self-powered solar-blind ultraviolet detectors based on the amorphous boron nitride films

Boron nitride (BN) has been a popular material in the field of ultraviolet detection because of its excellent thermal conductivity, high breakdown field strength, high absorption coefficient, and strong resistance to radiation. However, the harsh preparation conditions of its large-scale single crystal films limit the rapid development of its devices. In this work, amorphous BN films were deposited by the magnetron sputtering technique at a relatively low temperatures. On the basis of the films, the asymmetric Schottky junction solar-blind ultraviolet detectors were fabricated by the Ohmic and Schottky contact, respectively. The maximum responsivity and detectivity of the detectors are 6.4 μA/W and 2.5 × 1010 Jones under 20 V bias and 81.1 μW/cm2 ultraviolet light irradiation, respectively. More importantly, the fabricated asymmetric Schottky junction detector also achieves the stable self-powered characteristics due to the presence of its built-in electric field, and the performances are further improved after the rapid thermal annealing. The prepared BN asymmetric Schottky junction detector can operate without the need for the external power supply, which have many advantages such as simplifying the equipment structure and being able to operate in wireless. This work will provide a new reference for the design of the next generation of independent sustainable detectors.

Quantum Channel Extreme Bandgap AlGaN HEMT.

An extreme bandgap Al0.64Ga0.36N quantum channel HEMT with Al0.87Ga0.13N top and back barriers, grown by MOCVD on a bulk AlN substrate, demonstrated a critical breakdown field of 11.37 MV/cm-higher than the 9.8 MV/cm expected for the channel's Al0.64Ga0.36N material. We show that the fraction of this increase is due to the quantization of the 2D electron gas. The polarization field maintains electron quantization in the quantum channel even at low sheet densities, in contrast to conventional HEMT designs. An additional increase in the breakdown field is due to quantum-enabled real space transfer of energetic electrons into high-Al barrier layers in high electric fields. These results show the advantages of the quantum channel design for achieving record-high breakdown voltages and allowing for superior power HEMT devices.

Impact of an annealing atmosphere on band-alignment of a plasma-enhanced atomic layer deposition-grown Ga2O3/SiC heterojunction

Gallium oxide (Ga2O3) has attracted much attention because of its notable advantages, including its low cost and a high critical breakdown field. In this study, atomic layer deposition was used to deposit high-quality Ga2O3 onto a SiC substrate with high thermal conductivity. The band arrangement of the Ga2O3/SiC heterojunction was investigated by modulating oxygen vacancies using different post-annealing atmospheres. The results demonstrated that recrystallization of Ga2O3 resulted in a good crystalline state because of the rearrangement of Ga and O atoms following high-temperature annealing. Simultaneously, the roughness of all annealed samples increased. X-ray photoelectron spectroscopy analysis revealed a significant reduction of oxygen vacancy content in samples that were annealed in an oxygen atmosphere; this is attributed to the replacement of oxygen vacancies by oxygen atoms. Conversely, oxygen vacancies increased in an oxygen-free environment. The band offsets (valence band, conduction band) were respectively determined to be (−1.03 eV, 0.5 eV), (−0.63 eV, 0.9 eV), (−1.39 eV, 0.16 eV), and (−1.32 eV, 0.22 eV) for the as-deposited sample and annealed samples with O2, N2, and Ar atmospheres. Finally, the impact that various ratios of oxygen vacancies have on the energy band structure of Ga2O3 was studied using first-principles calculations. Calculations on heterojunctions confirmed that the introduction of oxygen vacancies reduced the potential barrier at the interface and promoted the movement of electrons. Thus, this study provides valuable insights for the design and application of Ga2O3/SiC heterojunction devices.

Ultra-high energy storage efficiency achieved through the construction of interlocking microstructure and excitation of depressor effects

Glass-ceramic capacitors struggle to balance high energy storage efficiency (η>90 %) and sufficient breakdown field strength (Eb), hindering their use in energy storage. Interface polarization, caused by the accumulation of free charge, reduces breakdown strength. We prepared glass-ceramic materials with varying contents of the glass phase using traditional melting techniques, adjusting the glass content to enhance an interlocking structure between the glass and crystal phases, reducing Interface polarization. Divalent metal oxide BaO in the glass stimulated a depressor effect, filling gaps and increasing resistivity. The optimal composition (x = 0.2) achieved a 95 % energy storage efficiency and an energy storage density of 4.4 J/cm3 at 680 kV/cm, while x = 0.25 reached an ultra-high energy storage efficiency of 99 %. Increasing glass content reduced activation energy for Interface polarization (Ei) from 1.27 eV to 1.08 eV. Samples with x = 0.2 exhibited low dielectric loss (∼0.005), high dielectric constant (∼142), ultra-high power density (∼52.8 MW/cm3), and ultra-fast discharge speed (∼26 ns), suggesting future potential for high-performance glass-ceramic materials.

Enhancing Resonant Second-Harmonic Generation in Bilayer WSe2 by Layer-Dependent Exciton-Polaron Effect.

Two-dimensional (2D) materials serve as exceptional platforms for controlled second-harmonic generation (SHG). Current approaches to SHG control often depend on nonresonant conditions or symmetry breaking via single-gate control. Here, we employ dual-gate bilayer WSe2 to demonstrate an SHG enhancement concept that leverages strong exciton resonance and a layer-dependent exciton-polaron effect. By selectively localizing injected holes within one layer, we induce exciton-polaron states in the hole-filled layer while maintaining normal exciton states in the charge-neutral layer. The distinct resonant conditions of these layers effectively break interlayer inversion symmetry, thereby promoting resonant SHG. This method achieves a remarkable 40-fold enhancement of SHG at minimal electric field, equivalent to conditions near the dielectric-breakdown threshold but using only ∼3% of the critical breakdown field. Our results highlight SHG sensitivity to carrier density and type, offering a new tool for manipulating SHG and probing quantum states in 2D excitonic systems.

Electronic properties of corundum-like Ir2O3 and Ir2O3-Ga2O3 alloys

In the hexagonal, corundum-like structure, α-Ga2O3 has a bandgap of ∼ 5.1 eV, which, combined with its relatively small electron effective mass, high Baliga's figure of merit, and high breakdown field, makes it a promising candidate for power electronics. Ga2O3 is easy to dope n-type, but impossible to dope p-type, impeding the realization of some electronic device designs. Developing a lattice-matched p-type material that forms a high-quality heterojunction with n-type Ga2O3 would open new opportunities in electronics and perhaps optoelectronic devices. In this work, we studied Ir2O3 as a candidate for that purpose. Using hybrid density functional theory calculations we predict the electronic band structure of α-Ir2O3 and compare that to α-Ga2O3, and study the stability and electronic properties of α-(IrxGa1−x)2O3 alloys. We discuss the band offset between the two materials and compare it with recently available experimental data. We find that the Ir d bands that compose the top of the valence band in α-Ir2O3 are much higher in energy than O p bands in α-Ga2O3, possibly enabling effective p-type doping. Our results provide an insight into using the Ir2O3 or Ir2O3-Ga2O3 alloys as p-type material lattice-matched to α-Ga2O3 for the realization of p–n heterojunctions.

Embedding Plate‐Like Pyrochlore in Perovskite Phase to Enhance Energy Storage Performance of BNT‐Based Ceramic Capacitors

AbstractNext‐generation electrical and electronic systems rely on the development of efficient energy‐storage dielectric ceramic capacitors. However, achieving a synergistic enhancement in the polarization and in the breakdown field strength (Eb) presents a considerable challenge. Herein, a heterogeneous combination strategy involving embedding a high Eb plate‐like pyrochlore phase in a high‐polarization perovskite phase is proposed. The embedded plate‐like pyrochlore increases the breakdown field strength and promotes the dynamic polarization response. Meanwhile, the strong spin–orbit coupling effect of the 5d electrons is conducive to the maintenance of the high polarization value of the perovskite. Consequently, the prepared multilayer ceramic capacitor (MLCC) exhibits an ultrahigh Eb and a high polarization. More specifically, an energy storage density (Wrec) of 14.9 J cm−3 with an efficiency of up to 93.4% is achieved for the optimized pyrochlore/perovskite phase. Furthermore, the MLCCs also exhibits an Wrec of ≈ 7.7 J cm−3 ± 4.5% in the temperature range of −50–180 °C. Therefore, this heterogeneous combination strategy therefore provides a simple and effective method for improving the energy‐storage performances of dielectric ceramic capacitors.

Single-crystalline High-κ GdOCl dielectric for two-dimensional field-effect transistors

Two-dimensional (2D) dielectrics, integrated with high-mobility semiconductors, show great promise to overcome the scaling limits in miniaturized integrated circuits. However, the 2D dielectrics explored to date still face the challenges of low crystallinity, diminished dielectric constant, and the lack of effective synthesis methods. Here, we report the controllable synthesis of ultra-thin gadolinium oxychloride (GdOCl) nanosheets via a chloride hydrate-assisted chemical vapor deposition (CVD) method. The resultant GdOCl nanosheets display good dielectric properties, including a high dielectric constant (high-κ) of 15.3, robust breakdown field strengths (Ebd) exceeding 9.9 MV/cm, and minimal gate leakage currents of approximately 10−6 A/cm2. The top-gated GdOCl/MoS2 field-effect transistors (FETs) exhibit commendable switch characteristics, a negligible hysteresis of ~5 mV and a subthreshold swing down to 67.9 mV dec−1. The GdOCl/MoS2 FETs can also be employed to construct functional logic gates. Our study underscores the significant potential of the 2D GdOCl dielectric for innovative high-speed operated nanoelectronic devices.