chapter  3
31 Pages


In chapter 2, the technologies involved in SiGe layer growth and the electronic properties of strained-Si1−xGex layers have been described with special emphasis on those properties which are related to their use as a narrow bandgap material in the base of a heterojunction bipolar transistor (HBT). In this chapter, we examine the underlying physics of the npn SiGe HBT, with particular emphasis on the fundamental differences between the operations of the SiGe HBT and the Si BJT.