Methods for making bipolar junction transistors including emitter-base and base-collector superlattices

A method for making bipolar junction transistor (BJT) comprising:

• forming a first superlattice on a silicon substrate defining a collector region and a sub-collector region therein, the first superlattice comprising a plurality of stacked groups of first layers, each group of first layers comprising a first plurality of stacked base silicon monolayers defining a first base semiconductor portion, and at least one first oxygen monolayer constrained within a crystal lattice of adjacent first base silicon portions;
• forming a silicon-germanium (SiGe) base on the first superlattice;
• forming a polysilicon emitter on the SiGe base;
• and
• forming a second superlattice between the collector region and the sub-collector region.

A method of making a bipolar junction transistor (BJT) comprising:

• forming a first superlattice on a silicon substrate defining a collector region and a sub-collector region therein, the first superlattice comprising a plurality of stacked groups of first layers, each group of first layers comprising a first plurality of stacked base silicon monolayers defining a first base semiconductor portion, and at least one first oxygen monolayer constrained within a crystal lattice of adjacent first base silicon portions;
• forming a silicon-germanium (SiGe) base on the first superlattice;
• forming an emitter on the SiGe base;
• forming a second superlattice between the collector region and the sub-collector region;
• and
• forming a third superlattice between the SiGe base and the emitter.