Patent ID: 7372084

Claim:
A bipolar transistor comprising: a plurality of semiconductor layers comprising a collector layer, a base layer in contact with the collector layer, a support layer in contact with the collector layer, and an emitter layer in contact with the base layer, the base layer having the opposite doping type of the collector layer and the emitter layer, wherein the plurality of semiconductor layers are formed to comprise: an intrinsic base region adjacent to and in contact with the emitter layer and an extrinsic base region, the extrinsic base region being adapted to make contact with a base electrode and extending laterally from the intrinsic base region; and a sub-collector region connected to a main collector region, located laterally from the main collector region and not interposed between the main collector region and the support layer to thereby increase transistor speed of the bipolar transistor, and adapted to make contact with a collector electrode, the sub-collector region being doped heavier than the collector layer, wherein a region of the collector layer adjacent to the extrinsic base region is selectively type converted to have the same doping type as the base layer, wherein the base layer, the emitter layer, and the collector layer comprise substantially of InAs 1−x P x , wherein x ranges from 0 to 0.5, wherein a region of the support layer adjacent to the type converted region of the collector layer is also selectively doped with the same doping type as the base layer, and wherein the sub-collector region is not interposed between the extrinsic base region and the support layer.