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 the 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 excess carriers in the turn-off process. The simulation results indicate that the turn-off time (t(off)) was reduced from 325 ns to 232 ns, and the turn-off loss (E-off) was decreased from 2.619 mJ to 1.375 mJ, while a similar on-state ability was maintained. This means that reductions of 28.6% in t(off) and 47.5% in E-off were achieved. The E-off of the two devices at different forward voltages (V-F) was compared by changing the carrier lifetime. As a result, a better trade-off between E-off and V-F was also achieved by the proposed HBL-IGBT. Moreover, the heterojunction of the HBL-IGBT can be formed with the plasma-activated direct bonding technology, which is compatible with the conventional fabrication process.