Silicon Carbide IGBT Research Articles

Injection enhanced SiC planar gate IGBT with partial Schottky contact emitter

A novel injection enhanced silicon carbide (SiC) planar gate insulated gate bipolar transistor with partial schottky contact emitter (PSE-IGBT) is proposed in this paper. The p-type schottky diode (p-SD) formed between the PSE and p-body region acts as a barrier to prevent the hole from flowing into the emitter, which enhances the conductivity modulation and optimizes the carrier distribution in the drift region in the conduction state. Therefore, compared with the conventional SiC IGBT (Con-IGBT), the device performance is significantly improved for the proposed structure. The simulation results show that the on-state voltage drop (Vceon) of the proposed SiC PSE-IGBT with the emitter metal of nickel (PSE-IGBTNi) and titanium (PSE-IGBTTi) is reduced from 6.61V of the SiC Con-IGBT to 5.83V and 5.48V, respectively. Meanwhile, the turn-off loss (Eoff) of the proposed SiC PSE-IGBTNi and PSE-IGBTTi is only 11.15 mJ/cm2 and 9.80 mJ/cm2, which is 47.5% and 53.9% lower than 21.25 mJ/cm2 of the SiC Con-IGBT at the Vceon of 6.4V, respectively. Furthermore, turn-off capability at high temperature and large current is checked and no degradation of the turn-off capability is observed for the proposed SiC PSE-IGBTs.

Evaluation of Long-Term Reliability and Overcurrent Capabilities of 15-kV SiC MOSFETs and 20-kV SiC IGBTs During Narrow Current Pulsed Conditions

Silicon carbide (SiC) is becoming a preferred technology of choice for power dense application compared with silicon (Si). A more comprehensive analysis of the long-term pulsed power reliability of SiC is necessary so that the technology can make the transition commercially. In this article, a testbed is utilized to evaluate research grade 15-kV SiC MOSFETs and 20-kV SiC IGBTs manufactured by Wolfspeed, a Cree Company. A testbed was developed here at Texas Tech University (TTU), Lubbock, TX, USA, to test these two devices. The narrow pulse testbed’s capacitor bank can be charged up to 10 kV and output square waveform pulse up to $2.0~\mu \text{s}$ . The waveform has a full-width at half-maximum pulse and is tested at a repetition pulse rate of three seconds. The electrical characteristics of the forward conduction and reverse breakdown of the device under test (DUT) are measured periodically during the experiment. The DUTs were pulsed at different current levels, up to 340 A (1.06 kA/cm2) for the IGBTs and 74 A (296 A/cm2) for MOSFETs, while the electrical device degradation was monitored. This work discusses the results of the long-term pulsed power reliability, failure modes, and their robustness in overcurrent operations of high-power SiC MOSFETs and IGBTs.

Improved Switching Characteristics Obtained by Using High-k Dielectric Layers in 4H-SiC IGBT: Physics-Based Simulation

Silicon Carbide (SiC) based MOS devices are one of the promising devices for high temperature, high switching frequency and high power applications. In this paper, the static and dynamic characteristics of an asymmetric trench gate SiC IGBT with high-k dielectrics- HfO2 and ZrO2 are investigated. SiC IGBT with HfO2 and ZrO2 exhibited higher forward transconductance ratio and lower threshold voltage compared to conventionally used SiO2. In addition, lower switching power losses have been observed in the case of high-k dielectrics due to reduced tail current duration.

Comparative Evaluation of 15-kV SiC MOSFET and 15-kV SiC IGBT for Medium-Voltage Converter Under the Same <italic>dv/dt</italic> Conditions

The 15-kV silicon carbide (SiC) MOSFET and 15-kV SiC IGBT are the two state-of-the-art high-voltage SiC devices. These high-voltage SiC devices enable simple two-level converters for a medium-voltage (MV) voltage source converter (VSC) topology compared with the complex three-level neutral point clamped and other multilevel topologies, which, otherwise, is required to realize for MV VSC with silicon devices. This paper characterizes the 15-kV SiC MOSFET module at 10- and 12-kV dc bus for two different configurations of the device under test. This paper also presents endurance test (continuous switching-mode experimental demonstration) of 15-kV SiC MOSFET for 10-kV output voltage for both a bidirectional and unidirectional dc-dc boost converter. Furthermore, this paper presents: 1) the switching loss comparison of 15-kV SiC MOSFET with 15-kV SiC IGBT for the same dv/dt condition; 2) the switching frequency limits of 15-kV SiC MOSFET for a dc-dc boost converter with a phase leg configuration at 10-kV output voltage; and 3) comparative evaluation of 15-kV SiC MOSFET and 15-kV SiC IGBT in a unidirectional dc-dc boost converter for 10 V output voltage.

Power Loss Analysis of Medium Voltage Three-Phase Converters using 15 kV/40 A SiC N-IGBT

Medium-voltage (MV) silicon carbide (SiC) devices such as the 15-kV SiC N-insulated gate bipolar transistor (IGBT) have better thermal withstanding capability compared with silicon (Si)-based devices. These devices also have lower switching and conduction losses at high switching frequencies and high power levels, respectively. The maximum safe operating junction temperature for the 15-kV SiC IGBT is 175 °C. This enables high power density design of the MV converters using this device. Heat sink with forced air cooling is considered for dissipating the heat generated during converter operation. In this paper, the power loss analysis of three-phase MV converters based on 15-kV/40-A SiC N-IGBT is discussed. The converter thermal analysis is carried out based on the experimental loss data and the continuous heat-run test of the device. It is supported by analytical calculations, PLECS thermal simulations, and FEM simulations in COMSOL Multiphysics software. Hardware prototypes of the converters are developed and the experimental results support the analysis. Experimental results are given for both hard-switched grid-connected converter and soft-switched dual active bridge converter. The paper mainly focuses on the semiconductor losses in the converter.

A Transformerless Intelligent Power Substation: A three-phase SST enabled by a 15-kV SiC IGBT

The solid-state transformer (SST) is a promising power electronics solution that provides voltage regulation, reactive power compensation, dc-sourced renewable integration, and communication capabilities, in addition to the traditional step-up/step-down functionality of a transformer. It is gaining widespread attention for medium-voltage (MV) grid interfacing to enable increases in renewable energy penetration, and, commercially, the SST is of interest for traction applications due to its light weight as a result of medium-frequency isolation. The recent advancements in silicon carbide (SiC) power semiconductor device technology are creating a new paradigm with the development of discrete power semiconductor devices in the range of 10-15 kV and even beyond-up to 22 kV, as recently reported. In contrast to silicon (Si) IGBTs, which are limited to 6.5-kV blocking, these high-voltage (HV) SiC devices are enabling much simpler converter topologies and increased efficiency and reliability, with dramatic reductions of the size and weight of the MV power-conversion systems.