Analysis of Transient Surge Current Mechanism in SiC MPS Diode With the Transition Region

In this work, Sentaurus TCAD was used to study the transient surge current mechanism of the 4H-SiC merged pin and schottky (MPS) diode. For the first time, a structure combining multicells with transition region was used to analyze the transient surge current mechanism of the MPS diode. The electrothermal simulation analysis of the surge characteristics of the MPS diode is carried out. Internal carrier distribution and lattice temperature in the surge current transient process of the device are mainly studied. The simulation results show that the hole current distribution and the electron current distribution in the MPS diode are not uniform. In the transient process of surge current, the transition region first enters the bipolar conduction mode, and then, the cells in the active region enter the bipolar conduction mode in the order from outside (close to transition region) to inside. The voltage–time (
${V}$
–
${t}$
), maximum temperature–time (
${T}_{\text {max}}$
–
${t}$
), and
${I}$
–
${V}$
curves of MPS diode in surge current events are obtained by simulation. Combined with the current density distribution diagram, the device behavior of multiple critical time nodes is analyzed in detail, and a reasonable explanation is given. In addition, the influence of different transition region contact types on the internal current distribution of the MPS diode is studied, and the simulation results are reasonably explained.