The Influence of Selected Material and Transport Parameters on the Accuracy of Modeling Early Voltage in SiGe-Base HBT

Using a new model of Early voltage (V
_A
), it is demonstrated that diffusion coefficient dependence on electric field and carrier velocity saturation at the collector end of the base has to be taken into account for accurate modeling of V
_A
in SiGe-based heterojunction bipolar transistors. The need to incorporate the dependence of SiGe material parameters on the local Ge content in the base is also addressed