Jeng-Bang Yau, Jin Cai, et al.
Journal of Applied Physics
An analytical model is developed for evaluating the effect of emitter depth variation on base and collector currents in a polysilicon-emitter SiGe-base bipolar transistor. It is shown that the base current is relatively insensitive to the Ge distribution in the single-crystalline emitter region, consistent with reported experimental results. On the other hand, the collector current and Early voltage are functions of the Ge distribution, Ge-free cap thickness, and final emitter depth. In particular, the current gain and Early voltage could have a strong dependence on emitter depth when there is a residual Ge-free layer left in the final quasi-neutral base. However, if the emitter-base junction is located in a constant-Ge region, then large current gains can be achieved that are relatively insensitive to emitter-depth variation, consistent with reported results. The inverse relationship between current gain and Early voltage is noted and contrasted with that of a wide-gap-emitter HBT.
Jeng-Bang Yau, Jin Cai, et al.
Journal of Applied Physics
Yuan Taur, Tak H. Ning
Materials Chemistry and Physics
Tak H. Ning
SPIE Advanced Lithography 2007
J. Cai, Tak H. Ning, et al.
S3S 2013