Investigation of Current Gain Degradation in 4H-SiC Power BJTs

Abstract

The current gain degradation of 4H-SiC BJTs with no significant drift of the on-resistance is investigated. Electrical stress on devices with different emitter widths suggests that the device design can influence the degradation behavior. Analysis of the base current extrapolated from the Gummel plot indicates that the reduction of the carrier lifetime in the base region could be the cause for the degradation of the gain. However, analysis of the base current of the base-emitter diode shows that the degradation of the passivation layer could also influence the reduction of the current gain.