A new degradation mode for advanced heterojunction bipolar transistors under reverse bias stress

This work shows and discusses the occurrence of a new failure mechanism affecting both collector and base currents under reverse BE junction stress. This is evident for very advanced SiGe and SiGe:C HBTs. This failure mode only affects the first steps of the degradation, exhibiting a correlated decrease of both base and collector currents, while keeping their ideality. Several experiments and analyses have been conducted for better understanding of this failure mode