Repetitive Recovery Analysis and Island Width Optimization of 4H-SiC Floating Island Devices

The 4H-SiC Floating Island (FI) device can break the 1-D SiC limit due to its ability to modulate the electric field in the drift region. In the previous research, we utilized the N+ buffer to overcome the forward recovery issue of the FI device. However, the FI device with N+ buffer can still suffer from repetitive forward recovery. In this work, we take the Floating Island JBS (FIJBS) as the research object. We will elucidate the cause of the repetitive recovery issue in the Fl device and analyze the dynamic equilibrium mechanism of electron-hole pairs. We also simulate the impact of the floating island width on the device's static and dynamic characteristics, which is beneficial for selecting an appropriate island width. To further improve the repetitive recovery performance of the device, we propose a novel structure with width-optimized islands. Simulation results indicate that the recovered resistance of the new structure is significantly reduced even after repetitive switching tests compared with the conventional FJBS. Moreover, this novel structure only changes the island width without requiring complex manufacturing processes. Those results demonstrate the great potential of this new structure for high performance power device.