InP/InGaAs collector-up heterojunction bipolar transistors fabricated using Fe-ion-implantation

This paper describes the first InP/InGaAs collector-up heterojunction bipolar transistors (C-up HBTs) with base and collector layers regrown onto the emitter layer. We used Fe-ion (Fe⁺)-implantation to define the intrinsic emitter/base junctions and a self-aligned fabrication processing for small-scale C-up HBTs. The collector-up configuration is attractive for ultra-high-speed and high power gain operation due to its low base/collector capacitance (C_BC). For scaling down transistors, the advantage of this configuration over the emitter-up configuration is clear because the parasitic C_BC corresponding to the extrinsic area can be neglected. This also makes the C-up HBTs feasible for low power dissipation devices