Hot carrier effects on the correlation resistance in Si/SiGe heterojunction bipolar transistors

In this paper the effects of hot carrier on the correlation resistance in SiGe HBT´s are investigated. Before the stress the correlation resistance was found to be comparable with the access series resistance while, after the stress, the correlation resistance decreases and the access series resistance increases. This increase suggests that the stress degrades the access regions of the transistor. On the other hand, the observed behaviour of the correlation resistance is explained in terms of an intrinsic noise source, Π-topology based low frequency noise model. It is shown that the correlation resistance is a useful indicator of surface recombination mechanisms. In particular, one intrinsic noise source in the model is associated with the degradation of the extrinsic base surface around the emitter perimeter