Voltage Devices Research Articles

Toward Understanding the Built-in Field in Perovskite Solar Cells through Layer-by-Layer Surface Photovoltage Measurements.

The built-in voltage (VBI) is a key parameter for solar cell operation, yet in perovskite solar cells the distribution, magnitude, and origin of the VBI remains poorly understood. In this work, we systematically studied the VBI in pin-type perovskite solar cells based on different hole transport layers (TLs). To this end, we determine the surface photovoltage (SPV) of partial and complete device stacks layer-by-layer by measuring the work function (WF) under dark and light (equivalent AM1.5G) conditions with Kelvin probe (KP) and photoemission spectroscopy (UPS) measurements in 3 different laboratories. We demonstrate that the SPV increases upon the addition of each additional layer until it equals the open-circuit voltage (VOC) of the full device. This suggests that both the electron and hole transport layer (HTL/ETL) enlarge the SPV, by improving the separation of photogenerated carriers. Yet, the contribution of both transport layers to the total SPV of the device is small (in the range of ≈100 to 200 meV) and the largest contribution to the SPV originates from the top metal electrode (≈500 meV). The results suggest that the VBI of pin-type perovskite solar cells is largely a result of the work-function difference of the electrodes. With regard to films (or incomplete cell stacks), our simulations can reproduce the measured SPV, and measured quasi-Fermi level splitting (>VOC) in partial cell stacks without a significant internal field consistent with the experimental data. This work establishes layer-by-layer SPV measurements, which are easily accessible, as a key tool for understanding device performance and internal energetics, similar to layer-by-layer QFLS measurements.

Impact of Minimal Silver Incorporation on Chalcopyrite Absorbers—Origins for Improved Open‐Circuit Voltages in (Ag,Cu)(In,Ga)Se2 Solar Cells

The influence of minimal amounts of Ag (0.5–1.4 at%) on elemental distribution and crystalline quality of (Ag,Cu)(In,Ga)Se2 (ACIGSe) absorbers grown by the three‐stage coevaporation without added alkali elements is reported. The elemental ratios affect the amount of Ag to be uniformly incorporated into the chalcopyrite absorber and the open‐circuit voltage (VOC) of the ACIGSe solar cell devices. Ag‐containing absorbers deposited at 530 °C achieve a best photoconversion efficiency of 18.2%. Due to an increased VOC, ACIGSe absorbers perform better than their Ag‐free variants at low deposition temperatures. The factors contributing to this increased VOC of low‐temperature devices are: 1) enhanced elemental Ga and In interdiffusion and hence their spatial distribution across the absorber thickness, leading to an increase in the minimum bandgap, 2) an improved absorber crystalline quality with larger grains resulting in high quasi‐Fermi‐level splitting and lower nonradiative losses. The photoluminescence data obtained on the ACIGSe absorbers reveal the corresponding variations in their bandgap and photoluminescence quantum yield. These material‐level insights into Ag incorporation in chalcopyrite help to advance the development of chalcopyrite‐based tandem solar cells, which—so far—is limited by the requirement of high deposition temperatures.

Power Imbalance Analysis and Minimum Imbalance Power Based Power Balance Control for Nonagonal MMC in FFTS‐Based Offshore Wind Farm

ABSTRACTNonagonal modular multilevel converter (MMC) can achieve three‐port direct AC‐AC conversion and has good low frequency performance. Additionally, due to its highly branch‐reused structure, it is advantageous in cost and size for the application in FFTS‐based offshore wind farm. However, the instantaneous power of the branches in nonagonal MMC has an inherent DC component which would result in power imbalance and system instability. The traditional way to suppress the imbalance power is to insert DC neutral point bias voltages and indirectly generating a DC component in circulating current. Together, they can offset the imbalance power. Nonetheless, this would significantly increase the voltage and current stress of converter switching devices and hence weakening its advantages in cost. To address this issue, the generating mechanism of power imbalance is analyzed by comparing nonagonal MMC with other power balanced converters. The formerly neglected phase angle difference of the same frequency ports is also considered and is proved to have a significant influence on the overall imbalance power. Accordingly, a parameter adjustment method is proposed to obtain minimum imbalance power for nonagonal MMC. The effectiveness of the parameter adjustment method is verified by RTlab results, and the overall imbalance power can be reduced by as great as 99.35%.

Dynamic Voltage and Frequency Scaling for Intermittent Computing

We present hardware/software techniques to intelligently regulate supply voltage and clock frequency of intermittently-computing devices. These devices rely on ambient energy harvesting to power their operation and small capacitors as energy buffers. Statically setting their clock frequency fails to capture the unique relations these devices expose between capacitor voltage, energy efficiency at a given operating frequency, and the corresponding operating range. Existing dynamic voltage and frequency scaling techniques are also largely inapplicable due to extreme energy scarcity and peculiar hardware features. We introduce two hardware/software co-designs that accommodate the distinct hardware features and function within a constrained energy envelope, offering varied trade-offs and functionalities. Our experimental evaluation combines tests on custom-manufactured hardware and detailed emulation experiments. The data gathered indicate that our approaches result in up to 3.75 × reduced energy consumption and 12 × swifter execution times compared to the considered baselines, all while utilizing smaller capacitors to accomplish identical workloads.

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.

Rational Design Dithieno[3,2-f:2',3'-h]Quinoxaline-Based Polymers with Optimized Molecular Configuration and Charge Transfer for High-Performance All-Polymer Solar Cells.

Due to poor planarity and weak intermolecular interactions of acceptor units which have two-dimensional configuration, the development of related polymers is slow. In this work, we synthesized a dithieno[3,2-f:2',3'-h]quinoxaline-based unit substituted with fluorinated thiophene, which can effectively expand the area of the acceptor unit. Then, it paired with three different benzodithiophene-based donor units, and three new polymers of PQTF-BT, PQTF-BTCl and PQTF-DTCl were obtained. PQTF-BT with thiophene side chain exhibits appropriate aggregation and crystallization performance, and the PQTF-BT:PY-IT all-polymer solar cells exhibit high device efficiency of 15.54 %. Meanwhile, PQTF-BTCl with chlorination strategy on thiophene side chain further enhances the open-circuit voltage of related devices. However, it has negative impact on the miscibility and charge transfer of the material, leading to a poor efficiency of 8.71 % in the PQTF-BTCl:PY-IT device. To reinforce miscibility, PQTF-DTCl with expanded backbone planarity was further studied. However, the big dihedral angles of the donor side chains disrupted the effective stacking of the molecules, resulting in great recovery of device performance to 13.42 %. This work provides research ideas for the design of polymers with two-dimensional configuration side chain and match selection of donor units.

Investigations of modulation method and stress mechanism for the growth of AlGaN channel heterostructures.

In this work, the strong connection between the channel and the barrier layer of AlGaN channel heterostructures has been investigated in detail. Unlike GaN as a channel material, AlGaN channel layers significantly influence the transport characteristics and quality of AlGaN barrier layers with increasing Al composition. Furthermore, the stress mechanism in the growth of the AlGaN layer has been thoroughly discussed. It has been revealed that the modulation of the channel layer stress alters its relaxation and enhances the consistency of the in-plane lattice constant, thereby improving channel layer quality. Moreover, this process reduces the tensile stress on the barrier layer, and improves the barrier layer quality and heterostructures performance. This work is not only beneficial for the achievement of high breakdown voltage and new generations of high-power RF devices, but is also instructive to the optimization and realization of the AlGaN material in deep-UV devices.

Hybrid improper ferroelectricity in a Si-compatible CeO2/HfO2 artificial superlattice

Hybrid improper ferroelectrics (HIFs), characterized by ferroelectric polarization arising from the rotation of two symmetry inequivalent antiferrodistortive modes, exhibit exotic properties such as T-independent dielectric constants and robustness against depolarizing field. Here, using first-principles simulations, we report a new P21 phase in a Si-compatible CeO2/HfO2 superlattice that exhibits remarkably robust hybrid improper ferroelectricity, induced by the in-plane oxygen rotations of two antiferrodistortive distortion modes. These non-polar distortions are coupled with a polar distortion through a trilinear coupling in the superlattice, stabilizing ferroelectricity as the competing ground state with the assistance of epitaxial strain. The estimated out-of-plane polarization (P=30.3μC/cm2) is switchable with a remarkably small energy barrier of 8.5 meV/atom and relatively smaller coercive field relative to bulk HfO2, expected to reduce the operational voltage of ferroelectric devices. Our discovery may offer unexpected opportunities for innovating high-performance, low-voltage devices, and promising advancements in next-generation CMOS compatible oxide-based electronics.

Interfacial Electronic Charge Trapping and Photonic Carrier Excitation Coupling in Solution-Processed Zinc-Tin Oxide Thin-Film Transistors Applied for Logic Gate Design and Quantized Neural Network.

Components needed in Artificial Intelligence with a higher information capacity are critically needed and have garnered significant attention at the forefront of information technology. This study utilizes solution-processed zinc-tin oxide (ZTO) thin-film phototransistors and modulates the values of VG, which allows for the regulation of electron trapping/detrapping at the ZTO/SiO2 interface. By coupling the excited photonic carrier and electronic trapping, logic gates such as "AND," "OR," "NAND," and "NOR" can be achieved. With the exponential growth in data generation, efficient processing and storage solutions are imperative. However, extensive data transfer between computing units and storage limits the level of artificial neural networks (ANNs). Consequently, quantized neural networks (QNNs) have gained interest for their reduced computational resource requirements and lower consumption. In this context, we introduce an optimized ternary logic circuit based on ZTO devices. By utilizing optical modulation to adjust the turn-on voltage of the single device, we demonstrate the achievement of ternary current states, thereby providing three distinct discrete states. This configuration can be extended to QNN computing, demonstrating multilevel quantized current values for in-memory computation. We achieved a handwriting digit recognition rate of 91.6%, thereby demonstrating reliable QNN hardware performance. This robust QNN performance indicates that the metal oxide phototransistor shows significant potential for future ternary computing systems.

Fluid Flow-Based Vibration Energy Harvesters: A Critical Review of State-of-the-Art Technologies

Energy harvesting technology plays an important role in converting ambient energy into useful electrical energy to power wireless sensing and system monitoring, especially for systems operating in isolated, abandoned or embedded locations where battery replacement or recharging is not a feasible solution. This paper provides an integrative study of the methodologies and technologies of energy harvesting from fluid flow-induced vibration (FIV). The recent research endeavors contributing to flow-based energy harvesting have been reviewed to present the state-of-the-art issues and challenges. Several mechanisms on FIVs including vortex-induced vibrations (VIVs), flutter, galloping and wake galloping are thoroughly discussed in terms of device architecture, operating principles, energy transduction, voltage production and power generation. Additionally, advantages and disadvantages of each FIV energy harvesting mechanism are also talked about. Power enhancement methods, such as induced nonlinearities, optimized harvester’s configuration, hybridization and coupling of aerodynamic instabilities, for boosting the harvester’s output are also elucidated and categorized. Moreover, rotary wind energy harvesters are reviewed and discussed. Finally, the challenges and potential directions related to the flow-based energy harvesters (FBEHs) are also mentioned to provide an insight to researchers on the development of sustainable energy solutions for remote wireless sensing and monitoring systems.

Research on Junction Temperature Smooth Control of SiC MOSFET Based on Body Diode Conduction Loss Adjustment

In a converter of actual working condition, the change in the current and voltage of the power device will cause the junction temperature to fluctuate greatly. This device is subjected to high thermal stress due to the change in the junction temperature. Therefore, it is necessary to adopt junction temperature control to reduce or smooth the junction temperature fluctuation, so as to realize the junction temperature control and improve the reliability of the device. At present, the methods for the junction temperature control of power devices have certain limitations and there are few active thermal management methods proposed for SiC device characteristics. In this paper, a method for realizing the smooth control of the junction temperature of a SiC device based on the conduction loss adjustment of the body diode for the SiC device has been proposed, considering that the conduction loss of the body diode is greater than the conduction loss of the SiC MOSFET. The conduction time of SiC MOSFET body diode was adjusted. By adjusting the conduction loss of the SiC MOSFET device, the fluctuation range of the junction temperature of the SiC MOSFET device was controlled, the smooth control of the junction temperature of the SiC device was realized, and the thermal stress of the device was reduced.

Effect of Cosmic Rays on the Failure Rate of Flexible Direct Current Converter Valves in High-Altitude Environment

Aiming at the significant needs of flexible DC converter valve applications in high-altitude areas, we investigate the effect of atmospheric neutrons on the failure rate of key core power devices in three kinds of converter valves, namely IGBTs, thyristors, and diodes. The safe working voltage boundary of the devices is obtained, and the failure rate caused by atmospheric neutrons in the real working environment of the power devices is calculated according to the results of the ground-accelerated irradiation test of atmospheric neutrons and the atmospheric neutron environment under the actual working conditions. The test results show that the failure rate of IGBTs, thyristors, and diodes caused by atmospheric neutrons is greatly affected by the blocking voltage, and the larger the blocking voltage is, the higher the failure rate of the device is. The research results can provide a basis for the design of the operating voltage of key core power devices of flexible DC converter valves and guide the evaluation of the failure rate and engineering design of the electronic system of DC ultra-high-voltage power transmission and transformation converter stations in the high-altitude environment of the Qinghai-Tibet Plateau.

Exotic ferroelectricity in strained BaZrS3 chalcogenide perovskite for photovoltaics

Ferroelectricity in solar cells is credited with a multitude of benefits, including improved charge carrier separation and higher than band gap device voltages, however most ferroelectrics are wide-gap materials that generate very little photocurrent. Some halide perovskites are ferroelectric, but they suffer from degradation, despite their otherwise excellent performance. Recently, BaZrS3, a chalcogenide perovskite has received attention due to its optimal band gap, non-toxicity, and superior stability. The ground state of BaZrS3 is reportedly a GdFeO3-type distorted perovskite (space group Pnma). Here, using first-principle calculations, we show that the polar Pna21 is thermodynamically as stable as Pnma. This new phase is weakly ferroelectric, exhibiting a net polarization of 0.27 µC/cm2 and a d33 piezoelectric coefficient of only ~1 pm/V. Under strain, the interplay between out-of-plane and in-plane octahedral tilts amplifies spontaneous polarization, spin splitting, and large polaron radii. These exotic traits are comparable to those of the popular halide perovskites.

Radiation-photon converter based on GaN single crystal coupled with multi-quantum-well luminescence structure

Converting radiation into optical signals is a fundamental method for nuclear radiation detection. However, traditional scintillators encounter a trade-off between efficiency and response speed. This research proposes a radiation-photon converter constructed from multi-quantum-well (MQW) structures integrated into radiation-sensitive materials, providing a unique solution to this challenge. The prototype was fabricated using a homogeneous epitaxial layer of GaN on a semi-insulating substrate. The radiation-photon conversion process was facilitated by directing charge carriers generated from radiation energy deposited in the semi-insulating substrate to the MQW layer via an external electric field. The converter exhibited a sensitive and rapid response to x-ray irradiation, enabling modulation of the excited photon wavelength through the MQW layers. Luminescence spectrum tests demonstrated that the net luminescence intensity increased with rising device voltage. Imaging experiments revealed that the grayscale values of device photographs, under the combined influence of electric fields and x rays, correlated with the trend in net current variation. These findings confirmed the effective conversion of radiation into optical signals through the modulation mechanism of the electric field, highlighting significant implications for the development of advanced radiation detection methodologies.

High Thermal Conductivity Polyelectrolyte Nanocomposite Electrical Insulation Thin Films

AbstractHigh‐power electronics require thin, conformal insulation that resists dielectric breakdown, while promoting removal of heat from the device. Recently, polyelectrolytes have shown promise in creating dielectric thin films, but their thermal conductivity remains relatively low (<1 W m−1 K−1). In this work, the layer‐by‐layer (LbL) assembly of polyethylenimine, mica clay, poly(acrylic acid), and hexagonal boron nitride is exploited to create a thin film dielectric material with relatively high thermal conductivity (through‐plane thermal conductivity of 1.87 ± 0.03 W m−1 K−1) and strong electrical insulation (breakdown strength of 152 kV mm−1). High thermal conductivity is obtained due to mica and hexagonal boron nitride nanoplatelets stretching through multiple layers. The performance benefits of this nanocomposite are demonstrated with a partial motor, where the nanocomposite greatly reduces the peak temperature of the motor when compared to state‐of‐the‐art polyimide insulation. This remarkable combination of thermal conductivity and dielectric breakdown strength represents a significant advancement in the electrical and thermal protection of high voltage devices.

(Ultra)wide bandgap semiconductor heterostructures for electronics cooling

The evolution of power and radiofrequency electronics enters a new era with (ultra)wide bandgap semiconductors such as GaN, SiC, and β-Ga2O3, driving significant advancements across various technologies. The elevated breakdown voltage and minimal on-resistance result in size-compact and energy-efficient devices. However, effective thermal management poses a critical challenge, particularly when pushing devices to operate at their electronic limits for maximum output power. To address these thermal hurdles, comprehensive studies into thermal conduction within semiconductor heterostructures are essential. This review offers a comprehensive overview of recent progress in (ultra)wide bandgap semiconductor heterostructures dedicated to electronics cooling and are structured into four sections. Part 1 summarizes the material growth and thermal properties of (ultra)wide bandgap semiconductor heterostructures. Part 2 discusses heterogeneous integration techniques and thermal boundary conductance (TBC) of the bonded interfaces. Part 3 focuses on the research of TBC, including the progress in thermal characterization, experimental and theoretical enhancement, and the fundamental understanding of TBC. Parts 4 shifts the focus to electronic devices, presenting research on the cooling effects of these heterostructures through simulations and experiments. Finally, this review also identifies objectives, challenges, and potential avenues for future research. It aims to drive progress in electronics cooling through novel materials development, innovative integration techniques, new device designs, and advanced thermal characterization. Addressing these challenges and fostering continued progress hold the promise of realizing high-performance, high output power, and highly reliable electronics operating at the electronic limits.

Modulation of Coloration Properties for Silver Deposition-Based Electrochromic Device Using Organic Capping Agents

The electrochromic (EC) device is capable of reversible color change with the electrochemical reaction of redox-active materials. EC technology is expected to be applied for light-modulating devices such as digital signages, e-papers, and smart windows. For practical applications, an EC device that enables full-color representation is desired. Considering a novel multicolor EC system, we focused on the superior colorability of Ag nanoparticles (AgNPs). Based on this concept, we have reported multicolor Ag deposition-based EC devices, achieving various optical states: transparent, mirror, black, cyan, magenta, and yellow by modulating of morphology of AgNPs. In chemical synthesis, various capping agents of metal nanoparticles have been reported to control the morphology of metal nanoparticles. In this study, an organic capping agent was introduced into an Ag deposition-based EC device as a capping agent for electrodeposited AgNPs to improve the coloration characteristics of EC devices and to precisely control the size and shape of the AgNPs. Through the coordination of capping agent molecules with Ag+ ions in the EC electrolyte, the critical voltage for the deposition of AgNPs decreased, resulting in a lower operating voltage of the EC device in comparison with the conventional one. Since particle growth and AgNP aggregation were suppressed by the capping effect of capping agents, achieving uniform electrodeposition of AgNPs. Aggregation suppression enabled vivid cyan, yellow, and red coloration using a simple driving procedure. The suppression of AgNP aggregation by capping agents was demonstrated even in an electrochemical system. Furthermore, the capping effect of capping agents also improved image retention. Better color retention properties were achieved even without the use of any counter-modified electrode cells.

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.

Degeneration mechanism of 30 MeV and 100 MeV proton irradiation effects on 1.2 kV SiC MOSFETs

In this study, we evaluated and characterized the effects of various proton irradiation energies and fluences on the electrical characteristics of SiC MOSFETs using a proton accelerator. The devices under test (DUTs) were fabricated utilizing 1.2 kV SiC MOSFET processes. To assess the impact of total ionizing dose (TID) and displacement damage (DD) on SiC MOSFETs, the DUTs were exposed to protons irradiation at energies of 30 MeV and 100 MeV, under ambient temperature conditions. Additionally, we examined the radiation hardness of DUTs under varying proton fluences, including 1 × 1012 cm−2, 1 × 1013 cm−2, 5 × 1013 cm−2, and 1 × 1014 cm−2.The results demonstrate that the threshold voltage (Vth) of the irradiated devices exhibited a negative shift, attributable to radiation-induced positive oxide trapped charges. This negative shift in Vth, coupled with the accumulation of positive trapped charges in the field limiting ring (FLR) oxide, resulted in augmented output currents and diminished breakdown voltage (BV) values. A significant reduction in current, ranging from 70% to 99%, was observed in the DUT subjected to irradiation at of 30 MeV and 1 × 1014 cm−2, highlighting the influence of DD. Conversely, irradiation at 100 MeV primarily revealed TID effects, characterized by a negatively shifted Vth. The on-state current at a gate voltage of 10 V and a drain voltage of 5 V of the DUT with irradiation of 100 MeV and 1 × 1014 cm−2 was a higher than that of DUT without irradiation because of a reduction of Vth.

Implementation and Experimental Analysis of Finding Partial Discharge Source between a Transformer and its Peripheral High Voltage Devices using Several Heterogeneous PD Sensors

Monitoring the transformer’s condition and fault diagnosis are essential to maintain the reliable operation of the transformer and maximize its lifespan. Usually, detecting PD signal from UHF PD sensor installed in a transformer is a method for monitoring the transformer conditions. However, the PD The PD signals leaked from Transformer will be detected by PD sensors due to peripheral high voltage. And it could be mistaken for as PD signal occurred in the transformer. In this paper, through experimental analysis, we propose a technology that installs several heterogeneous PD sensors in a transformer and a peripheral high voltage device and processes PD signals simultaneously to distinguish between PD signals generated inside a transformer and PD signals generated in peripheral high voltage devices. Several heterogeneous PD sensors, such as UHF sensors, TEV sensors, and HFCT sensors, are installed in transformers and peripheral high voltage devices, and the normalized amplitude of PD signals received from each sensor are compared and analyzed on a synchronized time and phase axis. For example, if the PD signals detected by the transformer and the peripheral high voltage device are on the same time and phase axis, and the normalized amplitude of PD signal from transformer is larger than the normalized amplitude of PD signal from the peripheral high voltage device. At this time, this PD signal is determined to have occurred inside the transformer. Whereas, if the normalized amplitude of the PD signal introduced from peripheral high voltage devices is larger than the normalized amplitude of the PD signal introduced from the transformer, it is determined to be PD signal introduced from the peripheral high voltage devices. With the results of experimental analysis, this technology can be effectively used to determine whether the detected PD signal from transformer PD sensor is originated from inside of the transformer or from peripheral high voltage device.