Asymmetric Split-Gate 4H-SiC MOSFET with Embedded Schottky Barrier Diode for High-Frequency Applications

Abstract

4H-SiC Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) with embedded Schottky barrier diodes are widely known to improve switching energy loss by reducing reverse recovery characteristics. However, it weakens the static characteristics such as specific on-resistance and breakdown voltage. To solve this problem, in this paper, an Asymmetric 4H-SiC Split Gate MOSFET with embedded Schottky barrier diode (ASG-MOSFET) is proposed and analyzed by conducting a numerical TCAD simulation. Due to the asymmetric structure of ASG-MOSFET, it has a relatively narrow junction field-effect transistor width. Therefore, despite using the split gate structure, it effectively protects the gate oxide by dispersing the high drain voltage. The Schottky barrier diode (SBD) is also embedded next to the gate and above the Junction Field Effect transistor (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 improves both static and switching characteristics at the same time. As a result, compared to the conventional 4H-SiC MOSFET with embedded SBD, Baliga′s Figure of Merit is improved by 17%, and the total energy loss is reduced by 30.5%, respectively.