Effects of Basal Plane Dislocations on SiC Power Device Reliability

Abstract

As silicon carbide power devices enter the commercial power electronics market there is a strong interest in all aspects of their reliability. This work discusses the degradation of MOSFETs due to basal plane dislocations (BPDs). During the forward bias of the MOSFET body diode, electron-hole recombination causes BPDs to fault and the resulting stacking faults in the drift layer degrade the MOSFET. As the stacking faults grow, the on-state conductivity of the MOSFET drift layer decreases, the off-state leakage of the drift layer increases, and the forward voltage of the body diode increases. Commercial 1200 V MOSFETs were stressed with a body current of 5 A or 10 A. The first generation of commercial MOSFETs showed significant degradation within minutes of stress time, whereas more recent MOSFETs did not show degradation for over 5 hours of stress time.