Planar InGaP/GaAs HBTs for high speed optoelectronic circuit applications

A fully planar self-aligned HBT fabrication process based on selective chemical beam epitaxial (CBE) regrowth of both the extrinsic base and subcollector layers is reported. Using this technology, cutoff frequencies of 50 and 70 GHz for fT and fmax, respectively, have been achieved for In0.49Ga0.51P/GaAs HBTs with 9 × 4 µm2 emitter-base junction area. High speed integrated circuits for lightwave communications including a 10 Gbit/s decision circuit and an 18 GHz dynamic frequency divider were successfully fabricated using these planar HBTs.