서강대학교

초록 (요약문)

4H-SiC split-gate Metal Oxide Semiconductor Field-Effect-Transistors (MOSFETs) and 4H-SiC MOSFETs with embedded Schottky barrier diodes are widely known to improve switching energy loss by reducing gate-drain capacitance and reverse recovery characteristics, respectively. However, in high voltage applications (> 3.3 kV), high electric fields are concentrated on the split gate oxide corner, causing a gate oxide reliability issues. In addition, the embedded Schottky barrier diode widens the cell pitch, degrading static characteristics such as specific on-resistance (RON,SP) and breakdown voltage. To solve this problem, in this thesis, an Asymmetric Split-Gate 4H-SiC MOSFET with embedded Schottky barrier diode (ASG-MOSFET) is proposed and analyzed by conducting a numerical TCAD simulation. Owing to the asymmetric structure of ASG-MOSFET, it has a relatively narrow junction field effect transistor (JFET) width. Therefore, despite using the split gate structure, it effectively protects the gate oxide by dispersing the high drain voltage in the off-state. The Schottky barrier diode (SBD) is also embedded next to the gate and above the JFET region. Accordingly, since the SBD and the MOSFET share a current path, the embedded SBD does not increase in RON,SP of MOSFET. Therefore, ASG-MOSFET significantly improves the switching characteristics without degradation of static characteristics. As a result, compared to the conventional planar MOSFET and planar with SBD, the total energy loss of the ASG-MOSFET was reduced by 79.2% and 29.8%, respectively.