Improved Device Characteristics Obtained Using a Novel High-K Dielectric Stack for 4H-SiC n-IGBT: HfO2-SiO2- AlN

We report on a novel method of stacking multiple oxide layers on 4H-SiC 20 kV IGBT. Instead of SiO2/SiC interface which is common for any SiC based MOS device, we found that the AlN/SiC interface would yield better results. We have performed 2D numerical simulations to analyze static characteristics for three combinations of dielectric stacks on IGBT: HfO2-SiO2, HfO2-AlN, and HfO2-SiO2-AlN (by maintaining the same equivalent oxide thickness value). In addition to higher transconductance (gm) and lower subthreshold swing (SS), the device with AlN/SiC interface offer comparatively lower RSP,ON and higher mobility with respect to temperature. Nevertheless, with a partial compromise on device characteristics improvement, insertion of SiO2 in the dielectric stack helps in suppressing the subthreshold current owing to higher band offset with respect to SiC. The turn off characteristics of the device is analysed using a clamped inductive circuit. Device with AlN/SiC has shown better dIc/dt and fall time compared to SiO2/SiC interface.

An Analysis of Static and Dynamic Characteristics of 12kV 4H-SiC n-IGBT using HfO2-SiO2 Dielectric Stack at High Temperatures

ABSTRACTIn this paper, the variation in device parameters is investigated with respect to temperature by considering the combination of HfO2-SiO2 on 4H-SiC n-IGBT. Two-dimensional numerical simulations using Setaurus TCAD have been performed to analyze the changes in static and dynamic characteristics. The switching waveforms have been analyzed using a clamped inductive circuit with and without HfO2. It seems that the presence of HfO2 in the dielectric stack has a considerable impact on the device turn off time.

On parameters determination of multi-port equivalent scheme for multi-winding traction transformers

This paper aims to present a new equivalent scheme of multi-windings traction transformers, based on multiport purely inductive circuit. The mathematical background of this equivalent scheme is described. The determination of the different scheme elements is made through a finite-elements calculation of both main and leakage inductances, for the case of a four-winding transformer. A procedure is defined, which allows to estimate the values of these elements from some measurements on the transformer at no-load and short-circuit operations. A specific strategy of short-circuit tests is described, allowing to determine all parameters in a rather simple way.

Electromagnetism

For Direct Current machines, Electromagnetism serves as the core. Therefore, in this chapter, the authors provide the fundamental background to the reader by giving basic information regarding electromagnetism. The chapter starts by discussing system of units, then the authors discuss regarding magnetic field, intensity of magnetic field, flux, flux density, amperes law, and units of flux. After that the authors discuss theory of magnetism, law of electromagnetic induction, Fleming's right and left hand rules, law of magnetic circuit, energy stored in a magnetic field and energy of inductive circuit. Hysteresis loop with core losses and hysteresis loss is then discussed. Finally, we discuss Eddy current loss.

Silicon Carbide Emitter Turn-Off Thyristor

A novel MOS-controlled SiC thyristor device, the SiC emitter turn-off thyristor (ETO) is a promising technology for future high-voltage switching applications because it integrates the excellent current conduction capability of a SiC thyristor with a simple MOS-control interface. Through unity-gain turn-off, the SiC ETO also achieves excellent Safe Operation Area (SOA) and faster switching speeds than silicon ETOs. The world's first 4.5-kV SiC ETO prototype shows a forward voltage drop of 4.26 V at 26.5 A/cm2 current density at room and elevated temperatures. Tested in an inductive circuit with a 2.5 kV DC link voltage and a 9.56-A load current, the SiC ETO shows a fast turn-off time of 1.63 microseconds and a low 9.88 mJ turn-off energy. The low switching loss indicates that the SiC ETO could operate at about 4 kHz if 100 W/cm2 conduction and the 100 W/cm2 turn-off losses can be removed by the thermal management system. This frequency capability is about 4 times higher than 4.5-kV-class silicon power devices. The preliminary demonstration shows that the SiC ETO is a promising candidate for high-frequency, high-voltage power conversion applications, and additional developments to optimize the device for higher voltage (>5 kV) and higher frequency (10 kHz) are needed.