High-performance InP/InGaAs co-integrated metamorphic heterostructure bipolar and field-effect transistors with pseudomorphic base-emitter spacer and channel layers

• Metamorphic BiFETs with pseudomorphic base–emitter spacer and channel layers.
• The FET was stacked on the top of the metamorphic HBT.
• High gate forward voltage, drain current, and transconductance are achieved in FET.
• Two In0.65Ga0.35As spacers effectively reduce collector–emitter offset voltage.
• The devices show a good potential for mixed signal integrated circuits applications.

In the InP/InGaAs metamorphic co-integrated heterostructure bipolar and field-effect transistors (BiFETs), the field-effect transistor (FET) with pseudomorphic channel layer was stacked on the top of the metamorphic heterostructure bipolar transistor (HBT) with pseudomorphic base–emitter spacer layers. In the FET, a relatively thin as well as heavily doped In0.65Ga0.35As pseudomorphic channel layer between two undoped InP layers was employed to enhance the gate forward operation voltage, drain current, and transconductance, simultaneously. On the other hand, after removing the top four layers of material structures, the studied HBT was fabricated on the metamorphic buffer layer. In the metamorphic HBT, the valence band discontinuity at InP/In0.65Ga0.35As heterojunction and emitter injection efficiency could be further extended than the conventional InP/In0.53Ga0.47As lattice-matched HBTs. Furthermore, the delta doping layer between two In0.65Ga0.35As spacer layers at emitter side could effectively eliminate the potential spike at base–emitter junction for reducing the collector–emitter offset voltage. Consequently, the co-integrated metamorphic devices show a good potential for mixed signal integrated circuits and systems applications.