6.5 kV schottky-barrier-diode-embedded SiC-MOSFET for compact full-unipolar module

Abstract

For higher-voltage SiC modules, larger SBD chips are required as free-wheel diodes to suppress current conduction of the body diodes of MOSFETs, which causes bipolar degradation following the expansion of stacking faults. By embedding an SBD into each unit cell of a 6.5 kV SiC-MOSFET, we achieved, without using external SBDs, a high-voltage switching device that is free from bipolar degradation. Expansion of the active area by embedding SBDs is only 10% or less, whereas the active area of external SBDs can be over three times larger than that of the coupled MOSFET. The fabricated 6.5 kV SBD-embedded SiC-MOSFETs show sufficiently high breakdown voltages, low specific on-resistances, no bipolar degradation, and good reliability.