Low Turn-Off Loss 4H-SiC Insulated Gate Bipolar Transistor With a Trench Heterojunction Collector

Abstract

In this work, an improved 4H-SiC insulated gate bipolar transistor (IGBT), or CTH-IGBT, with a trench p-polySi/p-SiC heterojunction on the backside of the device is proposed to reduce the turn-off energy loss (Eoff) and turn-off time (Toff). The electrical properties of the proposed and contrast structures are all simulated using the ATLAS simulation software to research the working mechanism of this improved structure. For the static performance, the specific ON-resistance (Ron,sp) and the figure of merit (FOM = VBR 2 / Ron,sp) are not influenced much as compared to the traditional structure at the same breakdown voltage (VBR) of 12 kV. However, with a prominent electron current path formed by the heterojunction region of CTH-IGBT, a very available conduction path to discharge the electrons during turn-off process is proved in this paper. The simulation results demonstrate that compared with the traditional structure, the turn-off energy loss of the CTH-IGBT is reduced by 76.4%, while the turn-off time is reduced by 85.0%. Index Terms-4H-SiC, heterojunction, Insulated Gate Bipolar Transistor (IGBT), turn-off loss, turn-off time, breakdown voltage. I. INTRODUCTION he performance of silicon-based devices is gradually approaching its limits, and it has become increasingly difficult to meet the application requirements of modern power electronic systems. The third-generation semiconductor material silicon carbide (SiC) has gradually replaced the use of silicon (Si) in power applications due to its wide band gap, high breakdown electric field, high thermal conductivity, high electron saturation drift speed and higher radiation resistance. It is widely used to make high-power devices for application in high temperature, high voltage, high frequency and radiation resistant operating environments and requirements [1-6].

A Novel 4H–SiC/Si Heterojunction IGBT Achieving Low Turn–Off Loss

“…Since Edward Van Brunt et al fabricated the 27 kV SiC IGBT [17], one of t obstacles for practical application has been the improvement of the dynamic pe [18]. The main problem of the switching characteristic is that excess carriers exit of the drift region and the buffer layer suppress the extension of the depletion la fore, most researchers propose some novel structures introducing a conductio to extract excess carriers [19][20][21][22], which effectively decreases toff and Eoff. How exists another way to extract excess carriers by enhancing the recombination r has been discussed less.…”

“…The main problem of the switching characteristic is that excess carriers exiting in part of the drift region and the buffer layer suppress the extension of the depletion layer. Therefore, most researchers propose some novel structures introducing a conduction method to extract excess carriers [19][20][21][22], which effectively decreases t off and E off . However, there exists another way to extract excess carriers by enhancing the recombination rate, which has been discussed less.…”

10kV+ Rated SiC n-IGBTs: Novel Collector-Side Design Approach Breaking the Trade-Off between dV/dt and Device Efficiency

“…However, the simulations were performed under low inductive load of 25A/cm 2 , the dV/dt reduction was rather limited, from 200kV/μs to 120kV/μs, and the impact on the on-state voltage drop was not included in the study. Finally, there have been suggestions of some more complex solutions such as the usage of a multizone collector design [8] or the usage of trenches on the collector side [9]. However, these structures are difficult to be manufactured and they don't provide information on whether they can affect the dV/dt.…”

A Novel 4H-SiC/Si Heterojunction IGBT Achieving Low Turn-off Loss

“…The main problem of switching characteristic is that excess carriers exiting in part of the drift region and the buffer layer suppress the extension of the depletion layer. Therefore, most researchers propose some novel structures introducing a conduction way to extract excessive carrier [5], which effectively decreases toff and Eoff. However, there exists another way to extract excessive carrier via enhancing recombination rate, which is less discussed before.…”