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Utilization of the integrated gate-commutated thyristor as a semiconductor switch in the series resonant converter for isolated medium-voltage dc–dc conversion offers an opportunity for high conversion efficiency while operating at the high switching frequency. Low conduction losses of the switch as well as decreased switching losses due to zero-voltage turn- on and low-current turn- off in the subresonant operating regime are reflected in the efficiency increase of the converter. This article explores the switching behavior of the semiconductor device under low currents while giving insight into the achievable turn- off energy losses and duration of the turn- off transients, as information required during the design process of series resonant converter. Experimental measurements confirm trends observed with simulation results related to turn- off delay process, providing further understanding of the switching losses and achievable performances under resonant mode of operation.

A new type of high-voltage termination, namely the “deep p-ring trench” termination design for high-voltage, high-power devices, is presented and extensively simulated. Termination of such devices consumes a large proportion of the chip size; the proposed design concept not only reduces the termination silicon area required but also removes the need for an additional mask as is the case of the traditional p+ ring-type termination. Furthermore, the presence of the p-ring under and around the bottom of the trench structure reduces the electric field peaks at the corners of the oxide, which results in reduced hot carrier injection and improved device reliability.

The planar Integrated Gate Commutated Thyristor (IGCT) concept is proposed to simplify the fabrication process of the device and improve the ruggedness as well as electrothermal performance of the device. The planar IGCT concept has been verified experimentally with 4.5kV devices fabricated on 4-inch Si wafers. Afterwards, the electrical characteristics of the planar IGCT were compared with that of the conventional (with trench or mesa gate) IGCT. Both the planar and the conventional IGCTs are fabricated with corrugated p-base referred to as High Power Technology (HPT) design. In addition, mixed-mode TCAD device simulations have been performed to verify the turn-off failure mechanism and to analyze the electro-thermal performance of the planar IGCT in reference to that of the conventional IGCT.

An antiparallel thyristor concept is introduced, where each thyristor occupies the whole silicon wafer This is achieved by full interdigitation of anode and cathode lateral and vertical structures of the antiparallel thyristors. The p-type cathode shorts on one wafer side serve as anode regions on the opposite side. This concept provides AC switch with turn-ON by any of the two gates and turn-off only after the load current ceased. Using an optimized irradiation procedure, we obtain device with turn-off capability called BiPCT. There the antiparallel thyristors show the recovery charge $\textbf{Q}_{rr} \lt 3000 {\mu}$As and commutation turn-off time $\textbf{t}_{\mathbf{q}}\lt 100 \mu \text{s}$ as experimentally demonstrated at four-inch 8.5 kV silicon devices. The concept is suitable for both Si and SiC.

In this letter, we present the “anode-side” SuperJunction trench field stop+ IGBT concept with drift region SuperJunction pillars placed at the anode side of the structure rather than the cathode side. The extent of the pillars toward the cathode side is shown to pose a tradeoff between fabrication technology capabilities (and cost) versus the device performance, by extensive TCAD simulations. The proposed device structure simplifies the fabrication requirements by steering clear from the need to align the cathode side features with the SuperJunction pillars. It also provides an extra degree of freedom by decoupling the cathode design from the SuperJunction structure. Additionally, the presence of SuperJunction technology in the drift region of the “anode-side” SJ Trench FS+ IGBT results in 20% reduction of ON-state losses for the same switching energy losses or, up to 30% switching losses reduction for the same ON-state voltage drop, compared with a 1.2-kV breakdown rated conventional FS+ Trench IGBT device. The proposed structure also finds applications in reverse conducting IGBTs, where a reduced snapback can be achieved, and in MOS-controlled thyristor devices.

A 94mm, Reverse Conducting-Integrated Gate Commutated Thyristor (RC-IGCT) for application at high DC voltage, up to 5.3kV has been manufactured and characterized. The design challenges for this type of device operating at such high voltage are to balance the losses to the ability to cool the device while keeping the snappiness of the diode part and the cosmic-ray failure rate to acceptable levels. The snappiness of the diode part has been overcome by implementing a new diode design in this high voltage (10kV) RC-IGCT, without influencing the technology curve under nominal operating conditions for the same silicon thickness. Furthermore, the experimental results show that the technology curve can be improved significantly with the new diode design by thinning the silicon while maintaining the soft reverse recovery behavior of the diode. The newly developed 94mm, 10kV RC-IGCT could be a device of choice for the low switching frequency high voltage power electronics applications, where one device could replace complicated series connection of two 4.5kV or 5.5kV devices per switch position.

In this paper, we propose a novel method to extract the accurate junction temperature of an integrated gate commutated thyristor (IGCT) during device conduction (on-state mode), by measuring the gate–cathode voltage of the device. We have shown that the gate–cathode voltage is a function of anode current and junction temperature $T_{\mathrm{vj}}$ . Indeed, the gate–cathode voltage of the device can be easily accessed in real-time operation of the device from its gate-unit without the need of any external power supply or thermal sensors. The method has been tested by both the simulations (semiconductor device simulations) and experiments (static and load cycling tests) for two different types of IGCTs. This method will enable us to continuously monitor the $T_{\mathrm{vj}}$ of the device during real-time operation of the power electronic converter, and hence, to predict and evaluate the remaining lifetime of the device.

A new design approach for bi-mode gate-commutated thyristors (BGCTs) is proposed for high-current controllability and low ON-state voltage drop. Using a complex multi-cell mixed-mode simulation model which can capture the maximum controllable current (MCC) of large area devices, a failure analysis was performed to demonstrate that the new design concept can increase the MCC by about 27% at room temperature and by about 17% at 400 K while minimizing the ON-state voltage drop. The simulations depict that the improvement comes from the new approach to terminate the GCT part in the BGCT way of intertwining GCT and diode regions for reverse conducting operation.

In this paper, we present and discuss simulation and experimental results obtained from investigating the impact of local alterations of the electric field profile in the power device planar junction termination region. Such local modifications are due to possible various extrinsic causes (manufacturing, operational or environmental) and are shown to have a critical influence on the device voltage blocking capability and reliability. The results point towards junction termination sensitivity to locally modified fields especially under voltage switching conditions due to higher leakage current densities in the modified area compared to the rest of the JT region.

This study presents the simulation and experimental results of the newly developed 2.5 kV reverse blocking-integrated gate commutated thyristor (RB-IGCT) which has been designed and optimised to have very low conduction losses and high turn-off current capability for DC solid state circuit breaker (SSCB) applications. The device has been optimised through anode engineering, thickness and resistivity to achieve the required blocking capability of 2.5 kV and to have very low conduction losses below 1 kW at 1 kA, that is, the on-state voltage drop is as low as 0.9 V at 1 kA. This study also presents the simulation and experimental results at the system level including the influence of the surge arrester (SA) which is connected in parallel to the RB-IGCT to clamp the overvoltage and to absorb the energy stored in the system inductance at the current interruption. The influence of different voltage rating SAs and parallel combination of SAs on the switching behaviour of the RB-IGCT has been investigated. A bi-directional SSCB for 1 MW application based on 2.5 kV RB-IGCT has been built successfully. The device simulations show that the results are in good agreement with the measurement results both at the device and system levels.

The Bi-mode Gate Commutated Thyristor (BGCT) is an advanced reverse conducting device aiming high power applications. Due to the high degree of interdigitation of diode parts and Gate Commutated Thyristor (GCT) parts, it is necessary to investigate how to best separate the two and at the same time, how to maximise the individual power handling capability. This work underpins the latter, for the GCT part. In achieving that, this letter details the optimisation direction, identifies the design parameters that influence the Maximum Controllable Current (MCC) and thereafter introduces a new design attribute, the “p-zone”. This new design not only improves the MCC at high temperature, but also at low temperature, yielding temperature independent current handling capability and at least 1000 A, or 23.5 % of improvement compared to the state-of-the-art. As a result, the proposed design constitutes an enabler for optimally designed bi-mode devices rated at least 5000 A for applications with the highest power requirement.

A parallel arrangement of a silicon (Si) IGBT and a silicon carbide (SiC) MOSFET is experimentally demonstrated. The concept referred to as the cross-switch (XS) hybrid aims to reach optimum power device performance by providing low static and dynamic losses while improving the overall electrical and thermal properties due to the combination of both the bipolar Si IGBT and unipolar SiC MOSFET characteristics. For the purpose of demonstrating the XS hybrid, the parallel configuration is implemented experimentally in a single package for devices rated at 1200 V. Test results are obtained to validate this approach with respect to the static and dynamic performance when compared to a full Si IGBT and a full SiC MOSFET reference devices having the same power ratings as for the XS hybrid samples.

The Bi-mode gate commutated thyristor (BGCT) is a new type of reverse conducting Gate Commutated Thyristor (GCT). This paper focuses on the maximum controllable current capability of BGCTs and proposes new solutions which can increase it. The impact of proposed solutions in the turn-ON and turn-OFF is also assessed. For this analysis, a 2-D mixed mode model for full-wafer device simulations has been developed and utilized.

The cross hybrid (XS) concept has been demonstrated experimentally with 3.3-kV Si Insulated Gate Bipolar Transistor (IGBTs) and SiC MOSFETs in parallel, and used to calibrate 2D Technology Computer Aided Design simulations. The XS hybrid offers lower switching losses compared with full Si IGBTs and reduced oscillations compared with full SiC MOSFETs. The current sharing mechanism between the IGBT and the MOSFET in the XS hybrid has been elucidated, showing that under typical switching conditions, the IGBT dissipate 98% of the XS hybrid turn-OFF losses compared with the SiC MOSFET. Since the current density of the IGBT in the XS hybrid is twice of that of the full IGBT solution, it exhibits higher dynamic avalanche. These features results in stress at device and package level, thereby compromising robustness and reliability. In order to overcome such issues, we show that increasing the turn-OFF gate resistance improves current sharing in the XS hybrid by delaying the turn-OFF of the MOSFET, and thereby suppressing dynamic avalanche in the IGBT.

A large area (150mm) high voltage (6.5kV) Reverse Conducting-Integrated Gate Commutated Thyristor (RC-IGCT) has been developed for low frequency high power electronics applications. The devices were fabricated with GCT to diode active area ratio of 1.4. The RC-IGCT wafers were designed with an outer ring gate structure to minimize the stray impedance for the gate signal and also to improve the thermal behavior of the device. In addition, the HPT+ (High Power Technology) platform has been employed in the GCT part to increase the safe operation area of the device (to achieve high controllable turn-off current capability). In this paper we present the measurement results of the 150mm, 6.5kV RC-IGCT during conduction and turn-off in both GCT (switch)- and diode-modes of operation. In addition, we have compared the technology trade-off curve of the 150mm, 6.5kV RC-IGCT with the state-of-the-art 6.5kV HiPak IGBT modules in switch-mode.

An approach to implement electrically robust MOSFETs in a functioning half-bridge will be investigated. For the first time, reverse conducting 3.3kV SiC MOSFETs have been fabricated with dilferent cell pitches from 14μm (p1.0) to 26μm (pl.8) that are able to withstand short circuit pulse of up to 10μs and a 9ms surge current event up to 15x the nominal current. LinPak half-bridge modules have been fabricated showing reduction of the switching loss by more than 90% compared to a silicon IGBT/diode half bridge.

This paper presents an experimental investigation of the dynamic performance of SiC 6.5kV JBS diodes. Using a hybrid Si SPT IGBT/SiC JBS diodes combination, we have analyzed the turn-off behavior limits of SiC JBS diodes and compared the result against a state-of-the-art Si PiN diode. The experimental results show that the JBS diodes can handle about 40A/chip at 125°C before going into thermal runaway. This maximum turn-off current value increases by about 50% when the diodes are operated at room temperature. The diodes dI/dt behaviour appear to be virtually independent of the DC-link voltage (at R G =18Ω). The comparison between turn-off curves for 6.5kV SiC and Si diodes shows that the use of SiC JBS diodes reduces the reverse recovery losses by more than 98%.

Analytical models have been proposed to describe the onset current density for the initial snapback in the transistor on-state mode and in the blocking state of reverse conducting-insulated gate bipolar transistors (RC-IGBT) for the stripe and cylindrical designs of the anode shorts. In cylindrical case, there are two possible ways in designing the anode shorts and the authors have proposed an analytical model for each of them. The considered RC-IGBTs are vertical with soft punch-through type buffer designs. The analytical model has been evaluated with the aid of 2-D device simulations and measurements. The authors have investigated the initial snapback phenomenon for different voltage class devices at a given technology (anode and buffer profiles) and found out that the snapback voltage increases with the blocking capability but not the snapback current density. The authors have also observed that the initial snapback phenomenon is more pronounced at lower temperatures. From the analytical model as well as simulation and measurement results, the authors have found that for a given voltage class and technology, the p + -anode width is the only remaining design degree of freedom which determines the initial snapback. The adjustment of the on-state losses can then be done with the proportion of the n + -short region.

Passivation of semiconductor devices reaches back to 1959, when Atalla and co-workers presented a study on passivation of silicon surfaces by thermally grown oxides [1]. However, it quickly became evident that oxide passivated surfaces did suffer from ionic conduction through the SiO2 layer already at low temperatures [2], thus impacting the long-term device reliability. In 1964, the first reports on the effect of phosphosilicate glass layers on top of the thermal oxide have been published, showing a stabilizing effect on the device reliability primarily by adjusting interface and oxide charges [3-5].

In this paper, we present for the first time, the experimental results of a “Bimode Cross Switch (BXS)-Hybrid” built with 3.3kV Silicon Enhanced Trench Bi-mode IGBTs (Si-ET-BIGT) and Silicon Carbide MOSFETs (SiC-MOSFET). Also, we have compared the static (on-state) and dynamic (switching) characteristics of the 3.3kV BXS-Hybrid (1 × Si-ET-BIGT + 2 × SiC-MOSFET) with the full SiC-MOSFET (4 × SiC-MOSFET) and full Si-ET-BIGT (2 × Si-ET-BIGT) reference samples. In addition, we have investigated the MOS gate control (blanking time tbl) influence in diode-mode during reverse recovery of the BXS-Hybrid and compared the results to those of the full Si-ET-BIGT. The experimental results show that BXS-Hybrid offers 45% and 75% reduction in the turn-off losses (in switch-mode) compared to full Si-ET-BIGT at nominal current (125A) and half-nominal current, respectively for nearly the same on-state voltage drop (at nominal current) or even much lower (at half nominal current). Also, the results show that the BXS-Hybrid offers 46% and 49% reduction in the reverse recovery losses (in diode-mode) compared to full Si-ET-BIGT at nominal current and half-nominal current, respectively. Furthermore, the results show that the reverse recovery losses can be reduced as much as 55% with the BXS-Hybrid compared to that of the full Si-ET-BIGT if the MOS gate control technique is used (for the tbl of 2μs). In addition, the BXS-Hybrid eliminates or reduces the oscillations compared to full SiC-MOSFET solution. In this study, the MOS gates of the devices in the BXS-Hybrid were connected together and controlled by the same single gate unit (with one common gate resistor).

The Bi-mode Gate Commutated Thyristor (BGCT) is a reverse conducting Gate Commutated Thyristor (GCT) where the diode regions are intertwined with GCT parts. In this work we examine the impact of shallow diode-anodes on the operation of the GCT and propose the introduction of optimised High Power Technology (HPT+) in the GCT part. In order to assess and compare the new designs with the conventional, a multi-cell mixed mode model for large area device modelling was used. The analysis of the simulation results show that the shallow diode does not affect the MCC whereas the introduction of the HPT+ allows for a step improvement.

In this work we present the simulation and experimental results of the “Cross Switch (XS)-Hybrid” built with 3.3kV Si-IGBTs and SiC-MOSFETs. We have analyzed the switching performance, mainly the turn-off behavior of the XS-Hybrid (a parallel arrangement of a Si-IGBT and a SiC-MOSFET) with the aid of Sentaurus TCAD device simulations. We discuss in detail the current sharing mechanism between these two devices and hence the distribution of the turn-off losses and the stress (peak power density, dynamic avalanche) on the devices during switching. In addition, we have investigated the turn-off behavior of the XS-Hybrid by variation of the area ratio between the Si-IGBT and SiC-MOSFET, variation of the gate resistance, and variation of the gate resistance ratio. To investigate the switching behavior of the XS-Hybrid, first the simulation models have been adjusted to match the experimental results of the 3.3kV Si-IGBT and SiC-MOSFET. Furthermore, the simulation and experimental results of the 3.3kV XS-Hybrid are compared with the full 3.3kV Si-IGBT and full 3.3kV SiC-MOSFET reference devices.

In this paper, we review the progress made recently for further developing the Integrated Gate Commutated Thyristor (IGCT) device concept for high power electronics applications. A wide range of newly introduced IGCT technologies are discussed and recent prototype experimental results as well as novel structures and future trends of the IGCT technology are presented. This will provide system designers with a comprehensive overview of the potentials possible with this device concept.

In this paper, we present the development of an air-cooled 1MW bi-directional DC Solid State Circuit Breaker (SSCB) based on recently developed 91mm, 2.5kV Reverse Blocking-IGCT (RB-IGCT). The power electronic switch (RB-IGCT) has been designed and optimized to have very low conduction losses, less than 1kW at 1kA (on-state voltage drop 6.5kA at 1.6kV, 400K) which are the most important concerns of semiconductor based circuit breaker. We also present the simulation and experimental results at the system level i.e. analyzed the influence of the Surge Arrester (SA) on the over-voltage transients during current interruption. We also analyzed the thermal management for the newly developed SSCB using ANSYS Icepak and validated experimentally.

In this work we present the first experimental results of a Bi-mode Gate Commutated Thyristor (BGCT). The BGCT is a new type of Reverse Conducting-Integrated Gate Commutated Thyristor (RC-IGCT). In a conventional RC-IGCT, the IGCT and diode are integrated into a single wafer but they are fully separated from each other. The novel BGCT on the other hand features an interdigitated integration of diode- and GCT-areas. This interdigitated integration results in an improved diode as well as GCT area, better thermal distribution, soft turn-off/reverse recovery and lower leakage current compared to conventional RC-IGCTs. We have discussed the advantages of a new diode anode design in BGCT, which is shallower than that of the conventional RC-IGCT. We have successfully demonstrated the BGCT concept with 38 mm, 4.5 kV prototypes and compared the on-state, turn-off and blocking characteristics with conventional RC-IGCTs both in GCT- and diode-modes of operation.

In this paper, a new type of reverse conducting IGCT referred to as Bi-mode Gate Commutated Thyristor (BGCT) is discussed. The concept of the BGCT follows an interdigitated integration approach of an IGCT and Diode into a single structure while utilizing the same silicon volume in both GCT and Diode modes. This results in improved thermal behavior and current capability. The BGCT design concept differs from that of the conventional Reverse Conducting IGCT (RC-IGCT) since in the BGCT, each individual segment is designed either as a GCT cathode or Diode anode. With the aid of 2-D Sentaurus TCAD device simulations, we have compared the static and dynamic characteristics of a 91 mm 4.5 kV BGCT model in both GCT and diode modes with that of the equivalent RC-IGCT and asymmetric IGCT. Furthermore, we have also investigated the BGCT performance by varying the GCT to Diode segments ratio.

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Application of the Integrated Gate Commutated Thyristor as a switching element in the medium voltage series resonant converter for DC-DC conversion offers the opportunity for increased conversion efficiency and higher switching frequency of the converter. Low current turn-off, already discussed in the previous works, shows promising results for increasing operating frequency of the converter, thus enabling the use of physically smaller components in the design, decreasing the total volume and weight of the solution. This paper presents the results of the switch characterization under single resonant current pulse operation, providing further insight into the turn-off process, relevant timing intervals and resulting losses, supported by TCAD simulations and experimental results.