InAlAs/InGaAs/InP DHBTs with polycrystalline InAs extrinsic emitter regrowth

We report DC transistor performance in InAlAs/InGaAs/InP double heterojunction bipolar transistors (DHBT) utilizing molecular beam epitaxy (MBE) regrown base-emitter junctions. We believe this to be the first report of an HBT utilizing non-selective-area regrowth in the formation of an active heterojunction. The process produces a very low-resistivity polycrystalline InAs extrinsic emitter, with a very low-resistivity emitter contact whose area is much larger than that of the base-emitter junction, facilitating low emitter resistance. The process also eliminates the need to form the base-emitter junction by etching and self-aligned metal liftoff, as we have found such processes have very low yield at deep submicron dimensions. This work is the first step in an attempt to parallel the highly scaled, high integration, low parasitic, and high-yield aspects of silicon transistors.