Study of Electrical Characteristics of a 4H-SiC Merged/PiN Schottky Adding a Low-Doped P-Barrier

Abstract

Silicon carbide (SiC) has received attention as a power device material because of its low resistance and leakage current owing to its wide band gap and low intrinsic carrier density. The structure of a silicon (Si) Schottky barrier diode (SBD), because of its large reverse leakage current, had not been used in high-voltage power semiconductor applications. However, when that material was replaced with SiC, SBD came to be used in power devices. In order to overcome the structural limitations, a merged PiN Schottky (MPS) structure, which has P+ barriers consisting of ohmic contacts instead of a floating P-barrier, has been proposed and is being actively researched. In this paper, we propose a structure that has a low-doped P-barrier consisting of ohmic contacts between the P+ barriers of the conventional MPS structure. The width and the doping concentration of the low-doped P-barrier are set as design variables and are optimized. In the optimized MPS diode, the breakdown voltage was improved by 9.7%, and the leakage current was decreased by 31.8%. In addition, this study confirmed that the on-resistance was reduced by 7.6%. The suggested structure overcomes the tradeoffs between breakdown voltage and leakage current, and can improve the off-state characteristics.