High-speed Switching Devices Research Articles

Ultra compact, high contrast ratio all optical NOR gate using two dimensional photonic crystals

An all-optical NOR gate is implemented using a two-dimensional photonic crystal waveguide. The paper provides a structure of an all-optical NOR gate constructed by introducing a line and point defect. The proposed NOR gate uses a hexagonal lattice structure with E shaped waveguide. The contrast ratio, response time and bit rate of three input NOR gate are 29.59 dB, 0.8 ps and 1.19 Tbps, respectively. The proposed gate is constructed with the operating wavelength of 1550 nm. The structure has been simulated and analyzed using Finite Difference Time Domain (FDTD) and Plane Wave Expansion (PWE) methods. It offers high contrast ratio, better response time with ultra-compact size. Hence it is suitable for high speed optical integrated circuits and switching devices.

Part I—Advancements in Power Converter Technologies: A Focus on SiC-MOSFET-Based Voltage Source Converters

Power converter technologies have become vital in various applications due to their efficient management of electrical energy. With the growing prominence of renewable energy sources such as solar and wind, the high penetration of power electronic converters has been justified. However, ensuring power quality has emerged as a significant challenge for grid-connected power converters. The divergence from the ideal sinusoidal waveform in terms of magnitude and frequency impacts both grid-side currents and voltages. Several studies have proposed solutions to address power quality issues at the load side. The advancement of power converters has been fueled by the development of high-performance microprocessors and the emergence of high-speed switching devices, such as SiC-MOSFETs. This paper focuses on the design of voltage source converters, particularly those based on SiC-MOSFET semiconductor devices. The article presents the design of H-Bridge cells, discusses two-level voltage source converters based on cascade H-Bridge cells in a parallel configuration with experimental fault analysis, addresses the seven-level voltage source converter topology, and explores the design and experimental results of the matrix converter. The findings underscore the importance of considering the entire converter design for improved performance at high switching frequencies. The article concludes by summarizing the main outcomes and implications of this research.

High temperature stability of H-diamond high frequency MOSFET with 300°C grown Al2O3 dielectric

The high frequency H-diamond metal-oxide-semiconductor field effect transistors (MOSFETs) were fabricated on single diamond substrate using 300°C ALD grown Al2O3 as gate dielectric and passivation layer. The devices gate length, gate/drain spacing and dielectric thickness are 100 nm, 2 μm, and 10 nm, respectively. The direct-current and frequency characteristics were investigated. The device shows a maximum saturation drain current of −492.6 mA/mm and gm of 135.2 mS/mm. The device shows good high temperature working performance, and the maximum saturation drain current only has a little decreasing of 7.6%. at 200°C. In addition, the device exhibits a maximum cut-off frequency of 36.2 GHz and maximum oscillation frequency of 70.5 GHz. The transient drain current response measurement indicates that the drain current can follow the changing of gate voltage at the frequency of 1 MHz. These results indicate that the Al2O3 dielectric is suitable for using in high frequency or the high-speed switching devices.

Ringing loss analysis and its influence on boost converter efficiency

Ringing of voltage and/or current waveforms is inevitable in hard-switching converters, especially when the operational frequency increases. The impact of ringing is increasing due to the development of high-speed switching devices. However, the extra loss introduced by ringing is not considered in the evaluation of the converter's total loss. This paper proposes detailed analysis of the ringing loss and its estimation method. It is shown that the ringing introduces extra loss, which is not included in the conventional method for loss estimation. The loss introduced by ringing is determined by its magnitude and the parasitic inductance in the power loop. In addition to the analysis, experiments are conducted on a boost converter with different ringing to evaluate the influence of ringing on the overall efficiency. It is shown that the ringing has a greater influence on efficiency under low current condition.

Broken-Gap PtS2/WSe2 van der Waals Heterojunction with Ultrahigh Reverse Rectification and Fast Photoresponse.

Broken-gap van der Waals (vdW) heterojunctions based on 2D materials are promising structures to fabricate high-speed switching and low-power multifunctional devices thanks to its charge transport versus quantum tunneling mechanism. However, the tunneling current is usually generated under both positive and negative bias voltage, resulting in small rectification and photocurrent on/off ratio. In this paper, we report a broken-gap vdW heterojunction PtS2/WSe2 with a bilateral accumulation region design and a big band offset by utilizing thick PtS2 as an effective carrier-selective contact, which exhibits an ultrahigh reverser rectification ratio approaching 108 and on/off ratio over 108 at room temperature. We also find excellent photodetection properties in such a heterodiode with a large photocurrent on/off ratio over 105 due to its ultralow forward current and a comparable photodetectivity of 3.8 × 1010 Jones. In addition, the response time of such a photodetector reaches 8 μs owing to the photoinduced tunneling mechanism and reduced interface trapping effect. The proposed heterojunction not only demonstrates the high-performance broken-gap heterodiode but also provides in-depth understanding of the tunneling mechanism in the development of future electronic and optoelectronic applications.

An RF Approach to Modelling Gallium Nitride Power Devices Using Parasitic Extraction

This paper begins with a comprehensive review into the existing GaN device models. Secondly, it identifies the need for a more accurate GaN switching model. A simple practical process based on radio frequency techniques using Vector Network Analyser is introduced in this paper as an original contribution. It was applied to extract the impedances of the GaN device to develop an efficient behavioural model. The switching behaviour of the model was validated using both simulation and real time double pulse test experiments at 500 V, 15 A conditions. The proposed model is much easier for power designers to handle, without the need for knowledge about the physics or geometry of the device. The proposed model for Transphorm GaN HEMT was found to be 95.2% more accurate when compared to the existing LT-Spice manufacturer model. This work additionally highlights the need to adopt established RF techniques into power electronics to reduce the learning curve while dealing with these novel high-speed switching devices.

Ultra Compact, High Contrast Ratio Based all Optical OR Gate Using Two Dimensional Photonic Crystals

In this paper, Two Dimensional Photonic Crystals (2DPC) based all-optical two/three input OR gate is proposed and designed. A logic gate is an elementary building block of a digital circuit. The proposed all-optical OR gate is designed by creating Y shaped defect with ring resonator in a hexagonal lattice structure. The performance of the proposed all-optical OR gate is investigated using the Plane Wave Expansion (PWE) and Finite Difference Time Domain (FDTD) method. The functional parameters namely normalized efficiency, contrast ratio, response time and bit rate, are calculated. The proposed all-optical OR gate operates at a wavelength of 1550 nm. The size of the proposed structure is compact in nature. It offers high contrast ratio and minimum delay time. Hence it is suitable for optical processors, high speed optical integrated circuits and switching devices.

Tungsten-doped Ge2Sb2Te5 phase change material for high-speed optical switching devices

The large impedance mismatch between the highly resistive amorphous state and the highly conductive crystalline state of Ge2Sb2Te5 is an impediment for the realization of high-speed electrically switched optical devices. In this paper, we demonstrate that tungsten doping can reduce this resistivity contrast and also results in a lower amorphous state resistivity. Additionally, it lowers the contact resistance, improves the optical contrast, and extends the face-centered-cubic state up to 350 °C, with a minimal impact on thermal conductivity.

Driver circuit to eliminate bridge leg crosstalk in SiC MOSFETs

This study involves the crosstalk caused by the high-frequency parasitic parameters in the driver circuits of SiC MOSFETs, which are high-speed switching devices. A lumped parameter model for the high-frequency crosstalk of a driver circuit was established. Then, the relationships between the parameters and crosstalk of the driver circuit were analyzed. Finally, an improved SiC MOSFET driver circuit was proposed. The optimized driver circuit parameters can reduce the driver signal oscillation and minimize the crosstalk of the driver circuit. Verification was performed on a test platform of a full-bridge LLC converter. Test results show that the improved driver circuit can remarkably suppress crosstalk, increase the turn-off speed of SiC MOSFETs and reduce the switching loss. This demonstrates the effectiveness of the driver circuit.

Matrix Extraction of Parasitic Parameters and Suppression of Common-Mode Conducted Interference in a PMSG-IDOS Rectifier Module

The rectifier module is the key part of a permanent magnet synchronous generator integrated DC output system (PMSG-IDOS) with low-voltage and high-current. The high-speed switching device of the rectifier module is the main source of electromagnetic interference (EMI). In this paper, the matrix extraction method is proposed to establish an accurate conducted interference model, and a 3D crimped SiC MOSFET model is established via Ansoft Q3D simulation software. The matrix of the parasitic parameters between poles of the MOSFET is simulated to extract the accurate parasitic parameters. Furthermore, a high-precision conducted interference simulation model of the pulse width modulation (PWM) rectifier system is established. Then, the space vector pulse width modulation (SVPWM) jump-backward control strategy based on the three-phase four-leg structure is proposed to suppress the common-mode interference, and the comparison with other two methods is carried out based on this model. Finally, the experimental platform of a 5 V/1000 A synchronous generator with rectifier is constructed, and conducted interference is tested in accordance with the simulated results. It demonstrates the accuracy of the model with parasitic parameters based on the matrix extraction method. This paper provides a more simple and effective reference method for the prediction study of conducted interference in power converter systems. After comparing the simulation results with the experimental results, it is proven that the SVPWM jump-backward control strategy based on the three-phase four-leg structure can ensure the output balance of the bridge leg and allow the common-mode (CM) interference to reach the ideal state.

Experimental investigation of the processes of degradation and transition to the normal state in CC-tapes under the action of current pulses

The study of the behaviour of CC tapes under the action of nonstationary current loads was conducted: a transition to the normal state was observed, as well as processes of CC-tape degradation. The obtained data make it possible to solve the problems associated with the creation of high-speed switching devices based on high-temperature superconductors, intended for functioning in superconducting energy storage devices, energy distribution and transmission systems, current limiters, and new types of transport. In addition to superconducting switches, pulsed current loads can occur in the mentioned above systems due to short-circuit conditions or other factors, and can lead to local heating of HTSC, especially if there is an inhomogenity in the critical current in the CC-tapes. In this work we present the results of a study of non-stationary processes second generation HTS tapes heating under the impulse current loads with amplitudes up to 2.2Ic (77K, self-field). Superconducting tapes with a copper protective layer were used as the samples. The I-V characteristics of the samples were measured under the action of current pulses during cooling in liquid nitrogen. Critical parameters (amplitude, rise time of the transport current) of the current pulses, leading to the degradation of the superconductor were obtained. local current carrying characteristics of CC-tapes investigated using Hall probe magnetometry. The features of the influence of local inhomogeneities in the distribution of the critical current of the tapes on the transition of the superconductor to the normal state are revealed.

An Aperiodic Modulation Method to Mitigate Electromagnetic Interference in Impedance Source DC–DC Converters

Rapid voltage and current transitions in switched-mode power converter circuits generate electromagnetic interference (EMI) which may interfere with other electronic systems. High-speed (e.g., wide bandgap) switching devices can improve circuit efficiency and compactness, but may increase the bandwidth of the interference generated. The peak interference is concentrated at harmonics of the fundamental switching frequency, and so may be reduced by modulating the converter switching frequency. However, converter topologies incorporating more than one switching device may not be suited to modulation of the switching frequency, and coordinated modulation of other pulse parameters is required to suppress interference. A relatively simple implementation of a hybrid pulse modulation technique is presented to suppress EMI in a quasi-Z-source converter comprising an impedance-source network and GaN-based H-bridge switching circuit. The technique uses two anharmonically related periodic signals to generate a modulated sawtooth carrier, which in turn generates coordinated switching pulses aperiodically modulated in position and width within a constant switching period. Experimental results demonstrated 10 dB suppression of the peak interference with negligible impact upon the converter's efficiency or output voltage. The proposed pulse modulation technique and its method of implementation are generic, and are expected to be widely applicable to other switched-mode dc–dc power converters.

Отключающая способность и электрическая прочность последовательно и параллельно соединённых коммутационных вакуумных устройств

The article describes newly developed mathematical models and procedures for predicting and estimating the electrical strength and breaking capacity of switching devices consisting of series- and parallel-connected triggered vacuum switches by using the measured characteristics of an individual triggered vacuum switch. One of possible application fields of the high-speed switching device may be its use as a combined short-circuiting and disconnecting device for protecting equipment from the effect of excessive short-circuit currents. The need for using such devices is stemming from the fact that the growth of power system capacities results in that the maximal short-circuit currents tend to exceed the breaking capacity of the power line circuit breakers. The use of a combined short-circuiting and disconnecting device will make it possible to continue the operation of these circuit breakers. The developed models and procedures are applied for estimating the electric strength and breaking capacity of a prospective high-voltage high-speed switching device VBK-110/80, which performs the function of a combined short-circuiting and disconnecting device with the rated breaking current equal to 80 kA (the effective value) intended for use in a 110 kV AC network.

(Invited) Transistor Applications Using Vertical III-V Nanowires on Si Platform

Vertical III-V nanowire (NW) is a promising channel material for high-speed switching devices in future integrated circuits because surrounding-gate structures have good electrostatic gate controllability while suppressing inherent large leakage current in III-V channels and outperform lateral switching devices in terms of power consumption while keeping good scalability. As for the integration of III-V NWs on Si, direct integration of vertical III-V NWs by selective-area growth has advantages for high -performance transistor applications because of position/size-uniformity and core-shell structure with modulation doping.

Data Intelligent Low Power High Performance TCAM for IP-Address Lookup Table

This paper represents current research in low-power Very Large Scale Integration (VLSI) domain. Nowadays low power has become more sought research topic in electronic industry. Power dissipation is the most important area while designing the VLSI chip. Today almost all of the high speed switching devices include the Ternary Content Addressable Memory (TCAM) as one of the most important features. When a device consumes less power that becomes reliable and it would work with more efficiency. Complementary Metal Oxide Semiconductor (CMOS) technology is best known for low power consumption devices. This paper aims at designing a router application device which consumes less power and works more efficiently. Various strategies, methodologies and power management techniques for low power circuits and systems are discussed in this research. From this research the challenges could be developed that might be met while designing low power high performance circuit. This work aims at developing Data Aware AND-type match line architecture for TCAM. A TCAM macro of 256 × 128 was designed using Cadence Advanced Development Environment (ADE) with 90 nm technology file from Taiwan Semiconductor Manufacturing Company (TSMC). The result shows that the proposed Data Aware architecture provides around 35% speed and 45% power improvement over existing architecture.

Scalable Sub-micron Patterning of Organic Materials Toward High Density Soft Electronics.

The success of silicon based high density integrated circuits ignited explosive expansion of microelectronics. Although the inorganic semiconductors have shown superior carrier mobilities for conventional high speed switching devices, the emergence of unconventional applications, such as flexible electronics, highly sensitive photosensors, large area sensor array, and tailored optoelectronics, brought intensive research on next generation electronic materials. The rationally designed multifunctional soft electronic materials, organic and carbon-based semiconductors, are demonstrated with low-cost solution process, exceptional mechanical stability, and on-demand optoelectronic properties. Unfortunately, the industrial implementation of the soft electronic materials has been hindered due to lack of scalable fine-patterning methods. In this report, we demonstrated facile general route for high throughput sub-micron patterning of soft materials, using spatially selective deep-ultraviolet irradiation. For organic and carbon-based materials, the highly energetic photons (e.g. deep-ultraviolet rays) enable direct photo-conversion from conducting/semiconducting to insulating state through molecular dissociation and disordering with spatial resolution down to a sub-μm-scale. The successful demonstration of organic semiconductor circuitry promise our result proliferate industrial adoption of soft materials for next generation electronics.

Design of a High-Voltage Signal Generator Applied Flashover Fault Detection

For cable flashover failure, a signal generator design ideas of the NC DC high flash - DC medium voltage flash - low-voltage flash based on three pulse method, consists of three components: the DC source, medium-high pressure unit and low pressure unit. DC source adopts AC 220V power supply, after rectification, chopping booster output. The output of the DC source through an inverter and high-frequency boost get the high-voltage unit. Low unit through the high-speed switching devices and capacitor charging and discharging achieve nanosecond pulse generation. In this paper, the various aspects of the design of the system have made a detailed description and simulation research.

Performance Analysis of Cntfet and Mosfet Focusing Channel Length, Carrier Mobility and Ballistic Conduction in High Speed Switching

Enhancement of switching in nanoelectronics, Carbon Nano Tube (CNT) could be utilized in nanoscaled Metal Oxide Semiconductor Field Effect Transistor (MOSFET). In this revi ew, we present an in depth discussion of performances Carbon Nanotube Field Effect Transistor (CNTFET) and its significance in nanoelectronic circuitry in comparison with Metal Oxide Semiconductor Field Effect Transistor (MOSFET). At first, we have discuss ed the structural unit of Carbon Nanotube and characteristic electrical behaviors beteween CNTFET and MOSFET. Short channel effect and effects of scattering and electric field on mobility of CNTFET and MOSFET have also been discussed. Besides, the nature o f ballistic transport and profound impact of gate capacitance along with dielectric constant on transconductance have also have been overviewed. Electron ballistic transport would be the key in short channel regime for high speed switching devices. Finally, a comparative study on the characteristics of contact resistance over switching capacity between CNTFET and MOSFET has been addressed.

Large current modulation in exfoliated-graphene/MoS2/metal vertical heterostructures

Graphene-based vertical field effect transistors have attracted considerable attention in the light of realizing high-speed switching devices; however, the functionality of such devices has been limited by either their small ON-OFF current ratios or ON current densities. We fabricate a graphene/MoS2/metal vertical heterostructure by using mechanical exfoliation and dry transfer of graphene and MoS2 layers. The van der Waals interface between graphene and MoS2 exhibits a Schottky barrier, thus enabling the possibility of well-defined current rectification. The height of the Schottky barrier can be strongly modulated by an external gate electric field owing to the small density of states of graphene. We obtain large current modulation exceeding 105 simultaneously with a large current density of ∼104 A/cm2, thereby demonstrating the superior performance of the exfoliated-graphene/MoS2/metal vertical field effect transistor.

Experimental Investigations and Ageing Studies on Effects of Insulating Barriers in Transformer Oil during High Frequency High Voltage Transients in Inhomogeneous Field

Insulating barriers utilized in complex high voltage insulation systems has been exploited widely by manufacturers of power apparatus. Barriers have found utility in a variety of power apparatus for protection against direct lightning strokes, as an interface at the boundaries of composite insulation materials etc. Though investigations have been carried out by researchers on the breakdown characteristics, barrier position in the gap, influence of space charge etc these characteristics have been analyzed based on aspects pertinent to classical testing procedures only. Advent of high speed switching devices in power systems provides avenues to investigate the effect of insulation performance due to High Frequency High Voltage (HFHV) also. Further, uncharacteristic failures in oil filled distribution transformers have been reported indicated fast transients as the major cause for failures which was not revealed during classical laboratory testing. This research focuses on the influence and effects of solid insulating barriers placed in transformer oil due to HFHV in inhomogeneous fields. Test cell arrangement has been fabricated for carrying out experimental investigations to adhere international standards. Exhaustive experimentation has been performed to infer the influence of the position of barrier, nature of field and breakdown voltage, erosion characteristics of the barrier at an appropriate range of frequencies. A detailed comparison between HFHV and classical power frequency voltage has been carried out. The nature of ionization at the barrier interface and the subsequent increase in the breakdown voltage as explained by Double Electric Layer (DEL) theory has been cross validated. In addition, a study has also been carried out to assess and characterize the ageing of oil based on Dissolved Gas Analysis (DGA) analysis using Weibull distribution.