An Analysis of Static and Dynamic Characteristics of 12kV 4H-SiC n-IGBT using HfO 2 -SiO 2 Dielectric Stack at High Temp
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MRS Advances © 2018 Materials Research Society DOI: 10.1557/adv.2018.422
An Analysis of Static and Dynamic Characteristics of 12kV 4H-SiC n-IGBT using HfO2-SiO2 Dielectric Stack at High Temperatures PavanVudumula and Siva Kotamraju Department of Electronics and Communication Engineering, IIIT Sricity, A.P., INDIA.
ABSTRACT
In 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.
INTRODUCTION MOS devices based on SiC are mainly used for high voltage applications. SiC IGBT is a promising candidate for use in high voltage power devices, due to faster switching and high voltage blocking capabilities [1]. The type of dielectric layer used in SiC power devices plays an important role in how the device performs. One important aspect of the insulator in these devices is the ability to withstand high electric fields. While SiC based transistors are commercialized, the combination of SiO2 and SiC interface had compatibility concerns, and cannot sustain higher electric fields[2]. An alternative is to replace the conventionally used SiO 2 with high-k dielectrics that can sustain high electric fields. This approach has been attempted earlier with Hafnium dioxide (HfO2) as the main gate dielectric and sandwiching SiO2 between of HfO2 and SiC [3]. SiO2 sandwiched between high-k dielectric (HfO2) and SiC has been considered as one of the promising dielectric stacks for future SiC based power devices. The purpose of this work is to understand the influence of HfO 2 on the switching transients at higher temperatures. Earlier research work on SiC IGBT with SiO 2 as the dielectric layer has shown initial reduction and then increase in forward voltage drop/RON with respect to temperature[4]. There is no research work published on a complete analysis of the static characteristics usingHfO2-SiO2 as a dielectric stack at high temperatures. This work highlights the changes in electrical characteristics of the IGBT with HfO2-SiO2 as a dielectric stack when the lattice temperature is varied from 300 K to 700 K.
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SIMULATION METHODOLOGY The structure of the IGBT device shown in figure 1 is built by using Sentaurus structure editor from Synopsys. Half-cell n-IGBT structure having an area of cross section 22 μm x 1 μm is chosen in this study.
Figure 1. Schematic cross-section view of 4H-SiC n-IGBT with HfO2-SiO2 as a dielectric stack.
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