Breakdown Voltage Research Articles

Enhancing the ferroelectric performance of Hf0.5Zr0.5O2films by optimizing the incorporation of Al dopant.

HfO2-based ferroelectric (FE) thin films have gained considerable interest for memory applications due to their excellent properties. However, HfO₂-based FE films face significant reliability challenges, especially the wake-up and fatigue effects, which hinder their practical application. In this work, we fabricated 13.5 nm-thick Al-doped Hf0.5Zr0.5O2(HZO) films with both uniform (UD) and optimized (OD) Al distributions, systematically investigating the effects of Al doping distribution on their ferroelectric and endurance performances. After optimizing the Al distribution, the OD samples exhibit significantly enhanced ferroelectricity, with a robust remnant polarization (2Pr) of 53.7 μC/cm2. Besides, compared to the undoped and UD HZO films, the OD samples exhibit enhanced dielectric performance, with lower leakage currents and higher breakdown voltages, suggesting that the optimized distribution suppresses oxygen vacancy generation and mitigates defect formation. Furthermore, the OD samples maintain a large 2Pr of 40.4 μC/cm2after 108, which can be rejuvenated back to 50.7 μC/cm2by higher voltage cycling. The enhanced dielectric performances and reversible phase transitions during cycling underline the potential of Al-doped HZO films with optimized distribution as reliable, long-endurance FE materials, advancing the development of HfO₂-based FE devices for future memory applications.&#xD.

Design and analysis of novel field plate-trench composite anode terminal in high-voltage Ga2O3 Schottky Barrier diode

Abstract To improve the breakdown voltage of Ga2O3 vertical Schottky Barrier diode (SBD), this article innovatively proposes a novel field plate-trench composite structure. Different from the traditional field plate structures and trench structures, the proposed composite structure innovatively adds a shallow trench under the field plate structure, greatly reducing the depth of the trench and relieving the etching difficulty. At the same time, simulation results show that the field plate-shallow trench composite structure can increase the breakdown voltage of the device from 543 V to 952 V, which is nearly 1.76 times higher than that of traditional devices. The new field plate-trench composite structure greatly improves the breakdown voltage of Ga2O3 vertical SBD, while also increasing the forward characteristics and the reliability of the device, having superiority in size, and alleviating the difficulty of the process. Our research work also has guiding significance for the research of other wide bandgap power devices.

A Review of Reliability Assessment and Lifetime Prediction Methods for Electrical Machine Insulation Under Thermal Aging

The thermal aging of insulation systems in electrical machines is a critical factor influencing their reliability and lifetime, particularly in modern high-performance electrical equipment. However, evaluating and predicting insulation lifetime under thermal aging poses significant challenges due to the complex aging mechanisms. Thermal aging not only leads to the degradation of macroscopic properties such as dielectric strength and breakdown voltage but also causes progressive changes in the microstructure, making the correlation between aging stress and aging indicators fundamental for lifetime evaluation and prediction. This review first summarizes the performance indicators reflecting insulation thermal aging. Subsequently, it systematically reviews current methods for reliability assessment and lifetime prediction in the thermal aging process of electrical machine insulation, with a focus on the application of different modeling approaches such as physics-of-failure (PoF) models, data-driven models, and stochastic process models in insulation lifetime modeling. The theoretical foundations, modeling processes, advantages, and limitations of each method are discussed. In particular, PoF-based models provide an in-depth understanding of degradation mechanisms to predict lifetime, but the major challenge remains in dealing with complex failure mechanisms that are not well understood. Data-driven methods, such as artificial intelligence or curve-fitting techniques, offer precise predictions of complex nonlinear relationships. However, their dependence on high-quality data and the lack of interpretability remain limiting factors. Stochastic process models, based on Wiener or Gamma processes, exhibit clear advantages in addressing the randomness and uncertainty in degradation processes, but their applicability in real-world complex operating conditions requires further research and validation. Furthermore, the potential applications of thermal lifetime models, such as electrical machine design optimization, fault prognosis, health management, and standard development are reviewed. Finally, future research directions are proposed, highlighting opportunities for breakthroughs in model coupling, multi-physical field analysis, and digital twin technology. These insights aim to provide a scientific basis for insulation reliability studies and lay the groundwork for developing efficient lifetime prediction tools.

Simulation of Normally-Off Vertical GaN MOSFET with a Novel Enhanced Sidewall Channel by Selective Area Growth.

In the present study, a novel normally-off vertical GaN MOSFET with an enhanced AlGaN/GaN channel on the sidewall has been proposed using the technology computer-aided design (TCAD) simulation. By using the selective area growth process, the trench structure and the enhanced sidewall channel are formed simultaneously, which is beneficial to enhance the conduction capability compared with the conventional trenched MOSFET. It demonstrates that a proper hole concentration and thickness of the p-GaN layer are key parameters to balance the threshold voltage, on-state resistance, and off-state breakdown voltage, resulting in the highest Baliga's figure of merit value. Furthermore, a p-GaN shield layer is also adopted as a junction termination extension to modulate the electric field around the trench bottom. By optimizing the device parameters, a normally-off GaN MOSFET with good performance is designed.

A reduced device symmetrical-asymmetrical multilevel inverter with self capacitor voltage balancing and reduced capacitor voltage ripple

ABSTRACT Multilevel Inverters (MLIs) have gained widespread acceptance in high-power conversion due to their distinctive features, including minimised harmonic distortion in the output and reduced voltage stress on power switches. Nevertheless, including numerous DC sources and switches in MLIs increases costs and system complexity. To address this challenge, this paper introduces a hybrid MLI topology featuring a reduced device count suitable for symmetrical and asymmetrical source configurations. The proposed hybrid MLI topology (PHMLIT) can produce a 9-level output voltage with a symmetrical configuration and 7- or 11-levels output voltage with an asymmetrical configuration. Moreover, the cascaded connection of the cells of the PHMLIT generates a broad range of voltage levels across the output. Additionally, a novel switching strategy is devised to minimise the size of the capacitor. The comparative analysis illustrates that the PHMLIT exhibits superior characteristics compared to conventional and recently developed topologies regarding the number of switches, DC sources, diodes, capacitors, and total blocking voltage (TBV). Finally, the feasibility of the PHMLIT is confirmed through various simulation and experimental tests.

Electron-Rich Heptacyclic S,N Heteroacene Enabling C-Shaped A-D-A-type Electron Acceptors With Photoelectric Response beyond 1000Nm for Highly Sensitive Near-Infrared Photodetectors.

A highly electron-rich S,N heteroacene building block is developed and condensed with FIC and Cl-IC acceptors to furnish CT-F and CT-Cl, which exhibit near-infrared (NIR) absorption beyond 1000nm. The C-shaped CT-F and CT-Cl self-assemble into a highly ordered 3D intermolecular packing network via multiple π-πinteractions in the single crystal structures. The CT-F-based organic photovoltaic (OPV) achieved an impressive efficiency of 14.30% with a broad external quantum efficiency response extending from the UV-vis to the NIR (300-1050nm) regions, outperforming most binary OPVs employing NIR A-D-A-type acceptors. CT-Cl possesses a higher surface energy than CT-F, promoting vertical phase segregation and resulting in its preferential accumulation near the bottom interface of the blend. This arrangement, combined with the lower HOMO energy level of CT-Cl, effectively reduces undesired hole and electron injection under reverse voltage. The PM6:CT-Cl-based organic photodetectors (OPDs) devices achieved an ultra-high shot-noise-limited specific detectivity (Dsh*) values exceeding 1014 Jones in the NIR region from 620 to 1000nm, reaching an unprecedentedly high value of 1.3 × 1014 Jones at 950nm. When utilizing a 780nm light source, the PM6:CT-Cl-based OPDs show record-high rise/fall times of 0.33/0.11µs and an exceptional cut-off frequency (f-3dB) of 590kHz at -1V.

Photoluminescence and Photocurrent from InGaN/GaN Diodes with Quantum Wells of Different Widths and Polarities.

We compare the optical properties of four pin diode samples differing by built-in field direction and width of the In0.17Ga0.83N quantum well in the active layer: two diodes with standard nip layer sequences and 2.6 and 15 nm well widths and two diodes with inverted pin layer ordering (due to the tunnel junction grown before the pin structure) also with 2.6 and 15 nm widths. We study photoluminescence and photocurrent in those samples (as a function of excitation power and applied voltage), revealing very different properties due to the interplay of built-in fields and screening by injected carriers. Out of the four types of diodes, the highest photocurrent efficiency was obtained (at reverse voltage) for the wide-well, inverted polarity diode. This diode also showed the highest PL intensity (at positive voltages) of our four samples. Diodes with wide wells have stable emission wavelengths (almost independent of bias and excitation power).

Trench MOS Schottky Diodes: A Physics-Based Analytical Model Approach to Charge Sharing.

Trench MOS Barrier Schottky (TMBS) rectifiers offer superior static and dynamic electrical characteristics when compared with planar Schottky rectifiers for a given active die size. The unique structure of TMBS devices allows for efficient manipulation of the electric field, enabling higher doping concentrations in the drift region and thus achieving a lower forward voltage drop (VF) and reduced leakage current (IR) while maintaining high breakdown voltage (BV). While the use of trenches to push electric fields away from the mesa surface is a widely employed concept for vertical power devices, a significant gap exists in the analytical modeling of this effect, with most prior studies relying heavily on computationally intensive numerical simulations. This paper introduces a new physics-based analytical model to elucidate the behavior of electric field and potential in the mesa region of a TMBS rectifier in reverse bias. Our model leverages the concept of shared charge between the Schottky and MOS junctions, capturing how electric field distribution is altered in response to trench geometry and bias conditions. This shared charge approach not only simplifies the analysis of electric field distribution but also reveals key design parameters, such as trench depth, oxide thickness, and doping concentration, that influence device performance. This model employs the concept of shared charge between the vertical Schottky and MOS junction. Additionally, it provides a detailed view of the electric field suppression mechanism in the TMBS device, highlighting the significant effects of the inversion charge on the MOS interface. By comparing our analytical results with TCAD simulations, we demonstrate strong agreement, underscoring the model's accuracy and its potential to serve as a more accessible alternative to resource-intensive simulations. This work contributes to a valuable tool for TMBS device design, offering insights into electric field management that support high-efficiency, high-voltage applications, including power supplies, automotive electronics, and renewable energy systems.

Silica modified by SiO2/silicone fluoroethylene acrylate emulsion superhydrophobic coating for electromagnetic wire study on the properties of the composite insulating layer

Abstract In this paper, a silicone-containing fluoroethylene acrylate emulsion was synthesized through emulsion polymerization, and a superhydrophobic coating was prepared by compounding it with modified SiO2 particles. The micromorphology, composition, and hydrophobic properties of the coating surface were analyzed using scanning electron microscopy, Fourier-transform infrared spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and water contact angle tests. The results revealed the presence of numerous micro-nanostructures on the coating surface, with a water contact angle of 161 ± 0.5°, indicating the characteristics of a superhydrophobic coating. A superhydrophobic composite insulating layer was created by modifying the quartz fiber insulating layer of electromagnetic wire with the superhydrophobic coating. The quartz fiber-insulated electromagnetic wire, treated with moisture, was evaluated for its insulation and breakdown voltage performance. The findings demonstrate that the superhydrophobic coating significantly reduces moisture absorption in quartz fiber, and the electromagnetic wire, even after moisture treatment, maintains excellent insulation and high breakdown strength, indicating promising applications in the field of electromagnetic wire insulation materials.

Low voltage and high bandwidth surface-illuminated three-terminal Ge-on-Si APD with multiple biasing configurations

In this work, a regulated-voltage biasing configuration is proposed for the Ge-on-Si avalanche photodiode (APD) structure. This design incorporates an extended n-charge layer to decrease the breakdown voltage and optimizes the absorption region thickness to reduce the electron transit time. By applying three electrodes to individually modulate the electric fields in the absorption and avalanche region, respectively, both of low avalanche breakdown voltage (−8.1 V) and high bandwidth (20.4 GHz) of the surface-illuminated detector can be achieved. Meanwhile, the sensitivity of weak light detection is improved to −45 dBm. The responsivity of the APD is 60.76 A/W at 1550 nm when the voltage is biased at −13.5 V. The low voltage and improved bandwidth can meet the requirements for weak light detection and other applications demanding such sensitivity.

Simulations of Attosecond Metallization in Quartz and Diamond Probed with Inner-Shell Transient Absorption Spectroscopy.

When dielectrics are hit with intense infrared (IR) laser pulses, transient metalization can occur. The initial attosecond dynamics behind this metallization are not entirely understood. Therefore, simulations are needed to understand this process and to help interpret experimental observations of it, such as with attosecond transient absorption (ATA). In this paper, we present first-principles simulations of ATA based on bulk-mimicking clusters and real-time time-dependent density functional theory (RT-TDDFT), with Koopmans-tuned range-separated hybrid functionals and Gaussian basis sets. Our method gives good agreement with the experiment for the breakdown threshold in silica and diamond. This breakdown voltage corresponds to a Keldysh parameter of approximately one and thus involves a transition to a regime where the dynamics are driven by tunneling. Pumping at an amplitude just below this value causes a mixture of multiphoton and tunneling excitations across the band gap to occur. The computed extreme ultraviolet and X-ray attosecond transient spectra also agree well with the experiment and show a decrease in optical density due to the transient population of the conduction band from the IR field. First-principles approaches such as this are valuable for interpreting the complicated modulations in a spectrum and for guiding future attosecond experiments on solids.

High-temperature performance of metal/n-Ga2O3/p-diamond heterojunction diode fabricated by ALD method

A metal/n-Ga2O3/p-diamond heterojunction diode with superior high-temperature performance was demonstrated in this work. The p-type diamond was lightly boron doped, and the Ga2O3 film was grown via atomic layer deposition without intentional doping. The forward current density increased with temperature, while the reverse current decreased at elevated temperatures. This behavior was attributed to the distinct carrier ionization dynamics across varying temperature ranges. Under high reverse voltage stress, the reverse current remained relatively stable, with no breakdown occurring up to 498 K. An avalanche breakdown voltage of 186 V at 498 K indicates the diode's robust high-voltage endurance capability. These findings underscore the potential of the metal/n-Ga2O3/p-diamond heterojunction diode for high-temperature and high-voltage applications.

Study of the effect of circular p-GaN gate on the DC characteristics of AlGaN/GaN HEMTs

Abstract In this paper, we use Silvaco-ATLAS two-dimensional numerical simulation to calculate the performance of two different circular-gate AlGaN/GaN HEMT device models. The influence of the special circular-gate structure on the DC characteristics of the AlGaN/GaN HEMT device is studied and compared with that of conventional devices. Compared with conventional, the threshold voltage of the drain-center and source-center circular-gate devices increased from 1.1 V to 1.5 V, while the transconductance improved from 245 mS/mm to 328 mS/mm and 285 mS/mm respectively. In the on-state of devices, the maximum saturation output current increased from 536 mA/mm to 620 mA/mm and 650 mA/mm. Furthermore, the breakdown voltage of the source-center circular-gate device rose from 765 V to 870 V compared to conventional devices; however, for the drain-center circular-gate device it was only at 685 V due to concentrated electric fields outside the drain region—this limitation can be effectively addressed by increasing the drain area. Simulation results demonstrate that circular-gate AlGaN/GaN HEMT devices can avoid edge effects, improve electric field distribution, and alleviate self-heating effects.

All-Fiber Micro-Ring Resonator Based p-Si/n-ITO Heterojunction Electro-Optic Modulator.

With the rapid advancement of information technology, the data demands in transmission rates, processing speed, and storage capacity have been increasing significantly. However, silicon electro-optic modulators, characterized by their weak electro-optic effect, struggle to balance modulation efficiency and bandwidth. To overcome this limitation, we propose an electro-optic modulator based on an all-fiber micro-ring resonator and a p-Si/n-ITO heterojunction, achieving high modulation efficiency and large bandwidth. ITO is introduced in this design, which exhibits an ε-near-zero (ENZ) effect in the communication band. The real and imaginary parts of the refractive index of ITO undergo significant changes in response to variations in carrier concentration induced by the reverse bias voltage, thereby enabling efficient electro-optic modulation. Additionally, the design of the all-fiber micro-ring eliminates coupling losses associated with spatial optical-waveguide coupling, thereby resolving the high insertion loss of silicon waveguide modulators and the challenges of integrating MZI modulation structures. The results demonstrate that this modulator can achieve significant phase shifts at low voltages, with a modulation efficiency of up to 3.08 nm/V and a bandwidth reaching 82.04 GHz, indicating its potential for high-speed optical chip applications.

Effect of Thermal Ageing on the Electrical Insulation Properties of the Oil-Paper Insulation

The article focuses on the electrical insulation properties of oil-paper insulation and its application in practice at AC voltage. It also discusses the effect of moisture and thermal ageing on the breakdown strength and breakdown voltage of oil-paper combinations. Measurements are made of the breakdown voltage and breakdown strength of liquid insulators and paper type KREMPEL-DPP, impregnated with two types of oils, SHELL Diala S4 ZX-I and Mogul Trafo CZ-A. The moisture content in the liquid insulants before and after thermal ageing is also measured.

Optimization of CuOx/Ga2O3 Heterojunction Diodes for High-Voltage Power Electronics.

This study optimizes the CuOx/Ga2O3 heterojunction diodes (HJDs) by tailoring the structural parameters of CuOx layers. The hole concentration in the sputtered CuOx was precisely controlled by adjusting the Ar/O2 gas ratio. Experimental investigations and TCAD simulations were employed to systematically evaluate the impact of the CuOx layer dimension and hole concentration on the electrical performance of HJDs. The results indicate that increasing the diameter dimension of the CuOx layer or tuning the hole concentration to optimal values significantly enhances the breakdown voltage (VB) of single-layer HJDs by mitigating the electric field crowing effects. Additionally, a double-layer CuOx structure (p+ CuOx/p- CuOx) was designed and optimized to achieve an ideal balance between the VB and specific on-resistance (Ron,sp). This double-layer HJD demonstrated a high VB of 2780 V and a low Ron,sp of 6.46 mΩ·cm2, further yielding a power figure of merit of 1.2 GW/cm2. These findings present a promising strategy for advancing the performance of Ga2O3 devices in power electronics applications.

Vacuum DC breakdown characteristics between grid electrodes with ion sputtering

Abstract In ion thrusters, grid electrodes are biased at high voltage to extract and accelerate ions. However, they are susceptible to vacuum breakdown which considerably undermines the ion thruster performance. To optimize the grid electrode design and improve the ion thruster longevity, the impact of ion sputtering on the vacuum DC breakdown characteristics of grid electrodes are systemically examined. The adopted seven-aperture grid electrodes are made of three materials including molybdenum, graphite, and stainless steel, which are exposed to Ar⁺ and Xe⁺ sputtering at energies of 400 eV and 1000 eV for durations ranging from 0.5 to 8 hours. It is found that the initial breakdown voltage, which means the first breakdown voltage after sputtering, generally decreased regardless of the electrode material as the sputtering time increased. However, the breakdown voltage rapidly increases with more repeated discharges. Each kind of electrode material demonstrates unique responses to ion sputtering and breakdowns. In comparison with metal electrodes, the graphite surface relatively easy to appear defects but exhibites the least insulation degradation. The metal surface remains relatively smooth, but breakdown voltage is significantly affected, with electrode materials such as stainless steel failing to recover to their initial insulation levels. Xe⁺ sputtering leads to greater breakdown voltage fluctuations during repeated discharges due to higher sputtering yield. Dark current is measured, and field enhancement factor is calculated to reveal correlations between local electric field and the breakdown voltage. Furthermore, micro particles are identified as major contributor to the first few times breakdown. Based on above observations, two kinds of distinct discharge mechanisms, including the cascade discharge induced by micro particles and the discharge induced by field emission are proposed to interpret experimental data.

A 614 MW/cm2 AlGaN-channel Schottky barrier diode with high breakdown voltage and high temperature sensitivity

A 614 MW/cm2 AlGaN-channel Schottky barrier diode with high breakdown voltage and high temperature sensitivity

Calculated Waveform and Peculiarity of Radiated Electric Field due to Collision ESD Between Metallic Spheres With Charging Voltages Below 1000 V Using Spark Resistance Law

ABSTRACTCollision ESD between charged metallic objects below 1000 V causes electromagnetic interference in electronic equipment and devices. This interference is being observed to intensify at lower charging voltages. The phenomenon was first identified by Masmitsu Honda, but its underlying mechanism remains unclear even today. Originally, the charging voltage and spark length of collision ESD are unknown due to measurement difficulties, making it extremely challenging to establish the relationship between the radiated electric field strength and the spark property in such cases. In this study, to clarify the above mentioned electromagnetic phenomenon in collision ESD, a method of calculating the radiated electric field along with a spark length estimated from the measurement strength of radiated field peak is presented using the spark resistance law developed by Rompe and Weizel. The validity is confirmed by our previous measurement data on radiated electric field due to the collision ESD between charged spherical electrodes with a diameter of 30 mm at charging voltages from 300 to 600 V, employing an optical field probe with a wideband up to 10 GHz. The estimated spark length is verified by comparing it with the spark lengths based on an empirical Paschen's formula between fixed electrodes and the discharge data from past literature on metal electrodes, revealing the peculiarity effect of the radiated electric field strength caused by “constant breakdown potential gradient” that occurs at charging voltages below 1000 V.

Design and Testing of MEMS Component for Electromagnetic Pulse Protection.

With the demand for high-safety, high-integration, and lightweight micro- and nano-electronic components, an MEMS electromagnetic energy-releasing component was innovatively designed based on the corona discharge theory. The device subverted the traditional device-level protection method for electromagnetic energy, realizing the innovation of adding a complex circuit system to the integrated chip through micro-nanometer processing technology and enhancing the chip's size from the centimeter level to the micron level. In this paper, the working performance of the MEMS electromagnetic energy-releasing component was verified through a combination of a simulation, a static experiment, and a dynamic test, and a characterization test of the tested MEMS electromagnetic energy-releasing component was carried out to thoroughly analyze the effect of the MEMS electromagnetic energy-releasing component. The results showed that after the strong electromagnetic pulse injection, the pulse breakdown voltage of the MEMS electromagnetic energy-releasing component increased exponentially in terms of the pulse injection voltage, and the residual pulse current decreased significantly from one-third to one-half of the original, representing a significant protective effect. In a DC environment, the breakdown voltage of the needle-needle structure of the MEMS electromagnetic energy-releasing component was 144 V, and the on-time was about 0.5 ms.