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

In this paper, a novel silicon carbide (SiC) insulated gate bipolar transistor (IGBT) with a 4H-SiC/Si heterojunction in buffer layer (HBL) is proposed to improve the turn-off characteristic. Compared with the conventional 4H-SiC IGBT, the polysilicon region is integrated in the buffer layer to form a natural potential well, which can help to store excessive carriers at the turn-off process. Simulation results indicate that the turn-off time (toff) is reduced from 325 ns to 232 ns and the turn-off loss (Eoff) is decreased from 2.619 mJ to 1.375 mJ, while a similar on-state ability is maintained. That means the reduction of 28.6% toff and 47.5% Eoff can be achieved. Based on the structure benefits, a better trade-off between Eoff-VF is also achieved for the proposed HBL-IGBT. Moreover, the heterojunction of HBL-IGBT can be formed with the plasma active direct bonding technology, which is compatible with the conventional fabrication process.