A 4H-SiC trench IGBT with controllable hole-extracting path for low loss

Abstract

A novel 4H-SiC trench insulated gate bipolar transistor (IGBT) with a controllable hole-extracting (CHE) path is proposed and investigated in this paper. The CHE path is controlled by metal semiconductor gate (MES gate) and metal oxide semiconductor gate (MOS gate) in the p-shield region. The grounded p-shield region can significantly suppress the high electric field around gate oxide in SiC devices, but it weakens the conductivity modulation in the SiC trench IGBT by rapidly sweeping out holes. This effect can be eliminated by introducing the CHE path. The CHE path is pinched off by the high gate bias voltage at on-state to maintain high conductivity modulation and obtain a comparatively low on-state voltage (V ON). During the turn-off transient, the CHE path is formed, which contributes to a decreased turn-off loss (E OFF). Based on numerical simulation, the E OFF of the proposed IGBT is reduced by 89% compared with the conventional IGBT at the same V ON and the V ON of the proposed IGBT is reduced by 50% compared to the grounded p-shield IGBT at the same E OFF. In addition, the average power reduction for the proposed device can be 51.0% to 81.7% and 58.2% to 72.1% with its counterparts at a wide frequency range of 500 Hz to 10 kHz, revealing a great improvement of frequency characteristics.