Bandgap engineered mono-crystalline silicon cap layers for SiGe HBT performance enhancement

摘要

A method for fabricating a heterojunction bipolar transistor (HBT) is provided. The method includes providing a substrate including a collector region; forming a compound base region over the collector region; forming a cap layer overlying the compound base region including doping the cap layer with a pre-determined percentage of at least one element associated with the compound base region; and forming an emitter region over the cap layer.