Single-Event Burnout Hardness for the 4H-SiC Trench-Gate MOSFETs Based on the Multi-Island Buffer Layer

In this article, the performance and triggering mechanism of the single-event burnout (SEB) of a 4H-SiC trench-gate (TG) MOSFET structure are evaluated by the 2-D numerical simulations. The novel N
⁺
island buffer 4H-SiC TG MOSFET and the conventional TG 4H-SiC MOSFET are analyzed and compared to examine whether an N
⁺
island region introduced in the second buffer can effectively reduce the impact ionization located at the N
^-
drift/N
⁺
buffer junction and improve device tolerance to the SEB. The TCAD simulation results revealed that compared with the conventional structure, which is a simple double-buffer structure, the N
⁺
island buffer-hardened structure changed the burnout threshold voltage, improving the SEB performance significantly. In addition, the results proved that the impact ionization played an important role in the SEB triggering mechanism, significantly affecting the SEB performance of the 4H-SiC TG MOSFET. The performance of the hardened N
⁺
island buffer with a different dopant concentration of N-buffer 2 and a size of N
⁺
island is discussed. The specific burnout threshold voltage at the optimal parameters of the proposed structure is 47% higher than that of the conventional structure.