High Current Switching Research Articles

High-Power and Repetion Rate Nanosecond Pulse Generation in “Diode Laser—Thyristor” Stacks

The “laser diode mini-bar (LDMB) – multi-element thyristor array (META)” vertical stack design is developed and its optoelectronic characteristics are studied. It is shown that adding a highly-doped layer to a low-voltage thyristor p-base leads to an increase in the repetition rate up to 1 MHz at nanosecond laser and current pulses. Laser pulses with 11.5 W peak power and 2.4 ns pulse width at 1 MHz repetition rate are demonstrated using the META chip, comprised of 4 elements, as a high-current switch. It is shown that the difference between LDMB elements’ turn-on delays does not exceed 400 ps. An increase in the pulse repetition rate from 10 kHz to 1 MHz at the operating voltage of 25 V is accompanied by insignificant LDMB heating (up to 3 °C) and a slight decrease in the laser pulse peak power (from 11.5 W to 11.1 W).

Toroidal Field Reversing Switch

A motor-driven, high-current switch is being designed by Staubli Electrical Connectors in collaboration with Princeton Plasma Physics Laboratory to reverse the DIII-D Toroidal field coil current. The existing field reversing procedure requires approximately 4 h of labor performed between run days to reconfigure the bus work, thus requiring a separate run day to complete experimental scans with both field directions. This typically results in different wall conditions which complicate the results or make them invalid. The proposed switch will complete the reversal process in approximately 4–5 min, between shots, so that wall conditions are not a factor, and easily fits within the 10–12 min DIII-D shot cycle. The switch is a compact design fitting into a $157.5\times41$ cm envelope. The switch uses two copper pins that slide between Staubli MULTILAM contacts. The switch is rated for total current of 180-kA dc for 10 s with a 12-min repetition rate; the maximum operating coil current is 124-kA dc. The switch diagnostics include: voltage drop, current monitor, thermal monitors, position sensors, and motor torque. The switch is rated for 300 cycles per year, and 3000 cycles overall before contact replacement, with contact inspection yearly. The design details and operation of the switch are covered in this article.

Resistive contribution in electrical-switching experiments with antiferromagnets

This paper shows that current-driven local annealing and electromigration facilitated by high switching currents can give rise to read-out signals of nonmagnetic origin that may mask the magnetic signal and can even be the dominant contribution to the signal.

Investigating the minimum post-burst energy required to function an exploding bridgewire detonator

The minimum energy required after bridge-burst to function a commercially available RP-1 exploding bridgewire detonator with a gold bridgewire was investigated using two capacitor discharge units (CDUs) making use of state-of-the-art on/off high-voltage high-current switches. Both switches are capable of shutting off the current flow in ≈100ns and the conduction time was varied systematically to limit the duration of electrical energy delivered from the CDU until a detonation go/no-go threshold was reached. It was found that the minimal extra electrical energy required for a soft-fire (a statistically marginal go) was approximately half that required for a hard-fire (a definite go). The measured energy required to function the RP-1 detonator from the 11.5 kV CDU was approximately 20 mJ greater than for the 600 V CDU, and it is postulated that this was due to arcing across the detonator terminals and an associated current shunt that was not efficient at depositing energy conducive to detonator functioning. Measurements of the bridgewire temperatures bursting in air showed that the maximum temperature reached was consistent (≈18kK) when sufficient energy was delivered that the detonator functioned (either soft- or hard-fire), but that the temperature for a sub-threshold bridgewire burst was significantly cooler at approximately 8 kK. Furthermore, it was demonstrated that the intensity of the light emitted at burst scaled with deposited energy. A related finding is that the light emission from the bridgewire peaks some tens of nanoseconds after both peak voltage and peak electrical power.

A State-of-the-Art 500-kV Hybrid Circuit Breaker for a dc Grid: The World's Largest Capacity High-Voltage dc Circuit Breaker

High-voltage dc (HVdc) circuit breakers (CBs) are a key technology of multiterminal dc (MTdc) systems and grids. In this article, a state-of-the-art 500-kV hybrid CB (HCB) topology is proposed and compared with other existing HCB solutions. Implementing the topology includes three important components: a modular designed high-current bidirectional solid-state switch (SS), an ultrafast mechanical switch (MS) based on a Thomson (CCDC) equipment with no conduction loss, whose corresponding functional verification test results have been presented in detail. On this basis, the overall 500-kV HCB and a comprehensive experimental platform are developed. Detailed experiments, including 25-kA turn-off and reclosing experiments, are conducted. The HCB was found to be capable of breaking a 25-kA current in 2.7 ms with 800-kV overvoltage, which is on par with the level of leading CBs worldwide.

Preliminary study of laser-triggered pseudospark switch

Laser-triggered pseudospark switches, also called back-lighted thyratrons (BLTs), are low pressure, high voltage, high current glow-mode switches The feasibility of BLTs is verified. The laser beams with wavelengths of 266 nm and 532 nm were used in the test. In the non-focused mode, the minimum trigger energy for 266 nm laser is 15 mJ, the anode ignition delay time is about 340 ns, and the time jitter is about 40 ns. The minimum trigger energy for 532 nm laser is 83 mJ, the anode ignition delay time is about 420 ns, and the time jitter is about 60 ns. In the focused mode, the minimum trigger energy for 266 nm laser is 4 mJ, when the laser trigger energy is 8 mJ, the anode delay time is 190 ns, the jitter is less than 1 ns. The minimum trigger energy for 532 nm laser is 6 mJ, when the laser trigger energy is 8 mJ, the anode delay time is than 240 ns, the jitter is less than 1 ns. The methods to further reduce the energy of the laser trigger will be studied in the future.

A Novel Current-Balancing Method for Paralleled MOSFETs in High-Current Solid-State Switch Applications: Paralleling a Large Number of Semiconductor Devices by Adding Inductances in Series

Due to theoretical and practical limitations in the current rating of individual power semiconductor devices, connecting them in parallel to achieve higher current ratings has been of special interest to engineers and researchers. One of the specific application areas for high-current paralleled semiconductors is solid-state switches. There might be a number of different reasons to use solid-state switches instead of the traditional mechanical contactors in a given application. To name a few examples, the mechanical contactors are inherently slow, have a limited number of operation cycles, yield much less power density with much higher profile compared to solid-state switches, and, last but not least, need a considerable amount of driving power to turn on and stay closed.

An analytical model of the surface-potential-based source-pocket-doped cylindrical-gate tunnel FET with a work-function-modulated metal gate

A new surface-potential-based analytical model for a source-pocket-doped cylindrical-gate tunnel field-effect transistor (FET) with a work-function-modulated metal gate is proposed herein. The inclusion of a highly doped source pocket layer improves the drain current by two decades because of the higher band-to-band tunneling probability of charge carriers in the vicinity of the tunneling junction. Also, the presence of the work-function-modulated cylindrical gate reduces the subthreshold swing (SS) further below 60 mV/decade and thus enhances the $$I_{60}$$ performance. The potential distribution of the model is determined using the two-dimensional (2D) Poisson equation with appropriate boundary conditions and plays a significant role in the calculation of the shortest tunneling distance and the drain current. The position and width of the pocket layer in the source region are optimized with the aim of achieving the maximum current switching ratio (ION/IOFF) and $$I_{60}$$ and least possible subthreshold swing. Due to its high current switching ratio, significantly improved $$I_{60}$$, and remarkably low SS characteristics, the proposed model represents one of the probable devices to replace complementary metal–oxide–semiconductor (CMOS) technology. The results of the analytical model are validated against those obtained using the Synopsys technology computer-aided design (TCAD) device simulator.

A New Single-Phase AC Voltage Converter With Voltage Buck Characteristics for Grid Voltage Compensation

Voltage sags and swells are the major problems of the power distribution system that arise due to uneven distribution of the single-phase and nonlinear loads. They severely degrade the power quality and may cause the failure of the equipment at the user's side. The voltage sag and swell issues are compensated by operating the AC voltage controllers with bipolar voltage gain characteristics. In these converters, high switching voltage and current, and a large number of switching devices are the main issues that cause unwanted power losses and result in reduced efficiency of the system. High voltage stresses may cause device failure due to the increase in dv/dt rating. The large count of switching devices results in high cost and high conversion losses. So here, we propose a novel AC converter with fewer switching devices that reduces switching voltage and current to have low conversion losses. The amplitude of the output is governed through the direct PWM control (DPWM) of one switch that controls the switching state of the other switch indirectly called indirect PWM control switch (IDPWM). The detailed analysis of the proposed converter is carried out to compare its performance with the existing converters. MATLAB/Simulink environment-based simulation results are proved through the experimental results obtained by developing a hardware prototype.

Superconducting nanowire single-photon detectors fabricated from atomic-layer-deposited NbN

High-quality ultrathin films of niobium nitride (NbN) are developed by the plasma-enhanced atomic layer deposition (PEALD) technique. Superconducting nanowire single-photon detectors patterned from this material exhibit high switching currents and saturated internal efficiencies over a broad bias range at a telecommunication wavelength of 1550 nm. Statistical analyses on hundreds of fabricated devices show a near-unity throughput yield due to the exceptional homogeneity of the films. The ALD-NbN material represents an ideal superconducting material for fabricating large single-photon detector arrays combining high efficiency, low jitter, and low dark counts.

Fast SiC Switching Limits for Pulsed Power Applications

Solid-state semiconductor switches are emerging as an attractive choice for the fast switching of compact, repetitive, and pulsed power systems. In particular, the high voltage and fast switching capabilities of SiC MOSFETs are well suited for many applications when appropriately gated. For instance, the turn-on and turn-off characteristics of such devices are strongly dependent on the gate driving circuitry. Traditional commercial gate drivers, typically utilizing push–pull or totem-pole driving topologies, are often not well suited for fast, high current switching with rise times on the order of 10–20 ns, as the driving performance is highly dependent on the combined RLC characteristics of the driving circuitry and the switching device. The proposed gate drive topology utilizes a current-carrying inductor to rapidly charge theMOSFET gate–source capacitance. A high-voltage inductive kick generates the necessary potential to drive the inductor current into the gate through the parasitic gate impedance. As the energy stored in the drive inductor is continuously variable, it can be adjusted such that the gate voltage settles to a lower value, typically 20 V, after the initial kick to prevent excessive gate–source overvoltage. With an inductive drive current of ~23 A, a peak $\text{d}I/\text{d}t$ of 25 kA $\mu \text{s}^{-1}$ was achieved for the tested bare SiC MOSFET die. Additionally, a peak $\text{d}I/\text{d}t$ of 13 kA $\mu \text{s}^{-1}$ was achieved with the TO-247 packaged device.

Bipolar Analog Memristive Switching of In2O3 Using Al Nanoparticles

Aluminum nanoparticles (AlNPs) were embedded into a sol-gel synthesized In₂O₃ thin film by using a combination of thermal evaporation and glancing Angle Deposition technique. Presence of different sizes of aluminum nanoparticles was confirmed from field emission gun scanning electron microscopy. The high-resolution X-ray diffraction confirms the formation of Al₂O₃ NPs by surface oxidation of aluminum nanoparticles. Embedded Metal-Oxide-Semiconductor like device Al/In₂O₃/AlNPs/In₂O₃/p-Si was fabricated, and its memristor behavior was analyzed. The Al/In₂O₃/AlNPs/In₂O₃/p-Si device possessed high current conduction and analog resistive switching as compared to Al/In₂O₃/p-Si device. Significant and consistent memory window up to 150 current (I)-voltage (V) loop was obtained for Al/In₂O₃/AlNPs/In₂O₃/p-Si device between ±6 V applied bias. The Al/In₂O₃/AlNPs/In₂O₃/p-Si device measured high free carrier concentration, i.e., (Nd)~1.93 × 1020 cm-3 calculated from capacitance (C)-Voltage (V) measurement. The memory was retained in accumulation and depletion regions as obtained from the C-V looping curves.

High peak optical power of 1ns pulse duration from laser diodes - low voltage thyristor vertical stack.

It is shown that the use of low-voltage GaAs/AlGaAs thyristors as high-speed and high-current switches in vertical stacks with semiconductor lasers ensures the efficient generation of high-power ns-duration laser pulses. The lasing and current dynamics in vertical stacks based on laser diode mini bar emitting at 1060 nm and a single as well as a double thyristor switch is studied. The possibility is demonstrated that a laser diode mini bar (with 3 laser emitters) together with a single thyristor switch can generate laser pulses with a peak power of 6 W with a duration of 950 ps and a peak current of 12 A for an operating voltage of 28 V. The use of a double thyristor switch leads to a broadening of the current pulse due to different delays in turn-on of the thyristor switches, while the peak power and duration of laser pulses increase to 8 W and 1.4 ns, respectively. It is found that the stage of low-speed turn-on of the thyristor limits the efficient generation of current and laser pulses of ns duration at low operating voltages (less than 21V). An efficient generation of current and laser pulses by low-voltage thyristors at control currents of 2-320 mA is ensured by efficient impact ionization in the region of the reverse biased p-n junction at high values of operating voltages (more than 21V).

Anode Failure Mechanism of GaAs Photoconductive Semiconductor Switch Triggered by Laser Diode

This paper presents an experimental study on the failure mechanism of high-current gallium arsenide photoconductive semiconductor switches (GaAs PCSSs) triggered by the laser diode. We propose a Blumlein pulse forming line to test the GaAs PCSS. The result shows that the damage of GaAs PCSS almost occurs at the anode under the circumstances that either anode or cathode is illuminated, since the highest amplitude of Gunn oscillation always occurs on the anode. We speculate that the failure of high-current GaAs PCSS is attributed to the Gunn effect according to the statistics about failure factors of GaAs PCSS. We use a scanning electron microscope to semiquantitatively analyze the compositions of the erosions microball or granules, which are gallium and arsenium. The result proves our speculation.

Optimization of Doping Profiles in Insulated-Gate Bipolar-Transistors Using a Large Scale Optimization Technique

There is much interest on the numerical and practical optimization of the doping profiles in semiconductor devices. This interest is mostly driven by the power semiconductor industry, which is in continuous search for higher breakdown voltage semiconductor switches that have lower on-state resistance, and high current handling capacity and switching speeds. Among the existing power semiconductor devices, insulated-gate bipolar-transistors (IGBTs) are becoming more and more attractive because of their high blocking voltage capabilities and on-state current. Although these devices suffer from a relatively lower switching speed compared to current state-of-the-art metal-oxide-semiconductor field-effect-transistors, IGBTs have already become the preferred switching devices in many power applications, such as induction heating applications, traction motors, etc. [1]. In this work we present numerical finite element optimization results for a realistic 70 mm-wide punch-through IGBT structure. The optimization focusses on the two-dimensional doping distribution of the gate, emitter and collector junctions, and of the drift and buffer layers in order to increase the breakdown voltage of the IGBT. The optimization method is based on an adjoint space technique that our group has recently developed for the design of nanoscale semiconductor devices, and which is adjusted here to compute the doping sensitivity functions of the breakdown voltage and on-state resistance in IGBTs [2-4]. These doping sensitivity functions show how sensitive the breakdown voltage and on-state resistance are when we add one additional acceptor or donor impurity at a particular location inside the semiconductor. Since the doping sensitivity functions provide information about the gradient of the breakdown voltage and on-state resistance with respect to the doping concentration they are instrumental for the numerical and practical optimization of IGBTs. As we will show at the conference, we are able to increase the breakdown voltage from approximately 300 V to over 700 V without deteriorating the on-state resistance of the transistor. In the full presentation we will describe how the adjoint method can be used to calculate the doping sensitivity functions of the breakdown voltage, on-state current and voltage, and on-state resistance. We will also present details about the numerical implementation of the optimization method, which is based on a modified gradient optimization appropriate for semiconductor devices. Note that most traditional optimization approaches such as the steepest descends method, the Broyden–Fletcher–Goldfarb–Shanno algorithm, or similar algorithms fail because of the doping concentration varies over many orders of magnitude, which vary can from region to region inside the same device.

Ovonic threshold switching selectors for three-dimensional stackable phase-change memory

Abstract

PASSWORD BASED ELECTRIC LOAD SWITCHING GEAR FOR THE SAFETY OF LINEMAN

Safety of human life is of a paramount importance. In high current switching system, switch gear protects electrical circuit. However there is need to provide confidence to working engineers during installation work on high voltage installations. To prevent accidental switching on of switch gear by unauthorized workforce, this paper proposed a more life secured switching password-enabled device that strengthen working confidence and inactivate unauthorized person from hazardous switching of electrical power installation without the notice of field working engineers.

Thermally Activated ReBCO Switches for Charging High-Current Magnets

Aiming at design improvements for the International Axion Observatory, alternative options for powering of the 20-kA magnet are under consideration. Use of high-Temperature superconductors in a transformer-rectifier system cooled by a single stage cryocooler at 40 K-50 K level is a promising option, which allows to avoid massive movable bus bars, current leads, and related services. The overall efficiency of such a magnet powering system is determined by the characteristics of high-current switches, which have to operate in a fast synchronous manner. We studied the performance of thermally activated superconducting switches made of adjusted 4-mm-wide ReBCO tapes, using etching of the tapes in a FeCl-3 bath to increase their resistance in normal state and to prepare low-mass heaters perfectly matching the tape surface. First experimental results on the 'off' state performance and time constants of the switches, when toggling between 'on' and 'off' states, are presented. Finally, we discuss a conceptual design of an all-ReBCO rectifier system comprising a superconducting transformer and thermally activated switches, which can be scaled up for charging large magnet systems like particle detector magnets where slow charging is feasible.

Design and optimization of 30 V fully isolated nLDMOS with low specific on-resistance for HVIC applications

In this paper, a novel 30 V fully isolated n-channel lateral DMOS (nLDMOS) with low specific on-resistance (RON,sp) is proposed and experimentally realized using 0.35 µm Bipolar-CMOS-DMOS (BCD) process. We optimized the process parameters, such as doping concentration of the high-voltage drift n-well (HVNW) layer, P-buried layer (PBL) and pre deep n-well (Pre-DNW) layer, for achieving a superior tradeoff between high breakdown voltage (BV) and the low RON,sp. The proposed nLDMOS is fully isolated from the substrate to support negative bias to drain and has a very lower RON,sp than other competitors in the similar technology, which is critical for devices used in high-voltage, high-current switching applications such as HVIC's. The fabricated device exhibits a BV of 42 V with RON,sp as low as 15 mohm-mm2 . Besides, the new structure is fully compatible with standard 0.35 µm BCD technology, with a margin of up to 15% in process variation, which is large enough to meet the industrial requirement for mass production. Hence, it is not only high performance but also a low-cost solution.

Influence of HfO2 interlayers on magnetocrystalline anisotropy in Fe|MgO|Fe magnetic tunnel junction: First-principles investigation

Perpendicular magnetic anisotropy (PMA) is important for MgO based magnetic tunnel junction and magnetic random access memory to be integrated on a large scale due to high thermal stability and low critical switching current. Here, we applied the density functional theory to study the effect of HfO2 inserting layers on PMA of Fe|MgO|Fe tunnel junction. It was found that the magnetocrystalline anisotropy (MCA) of the junction for 5 layers Fe electrode was up to 1.95 mJ/m2 with one unit cell HfO2 interlayer, while it was 1.72 mJ/m2 without the interlayer. More importantly, analyzed by the layer and orbital-resolved MCA based on the second-order perturbation theory, MCA characters and the underlying mechanism of PMA become very different after inserting HfO2. The remarkable difference is the MCA contribution of the second interfacial Fe layers, which is about 0.4 mJ/m2 for Fe|MgO|Fe junctions, while it was larger than 0.7 mJ/m2 for Fe|HfO2|MgO|HfO2|Fe junctions. Furthermore, Fe-dz2 and O-pz hybridization plays a crucial role in MCA contribution from the first interfacial Fe layers since the interfacial Fe–O bond length reduces from 2.20 Å to 1.77 Å with inserting HfO2 layers. Besides, the reduction in Fe–O bond length can redistribute the orbital-resolved electrons of the second and third closest Fe layer to the interface to enhance their absolute values of MCA contributions, which results in the strong dependence of MCA on Fe thickness.