Carbon-doped base GaAs-AlGaAs HBT's grown by MOMBE and MOCVD regrowth

High-quality GaAs-AlGaAs heterojunction bipolar transistors (HBTs) in which the carbon-doped base layers (p=10/sup 10/-10/sup 20/ cm/sup -3/, 400-800 AA thick) and Sn-doped collector and subcollector layers are grown by metalorganic molecular-beam epitaxy (MOMBE) and a subsequent regrowth using metalorganic chemical vapor deposition (MOCVD) is used to provide the n/sup +/ AlGaAs emitter and GaAs/InGaAs contact layers are discussed. A current gain of 20 was obtained for a base doping of 10/sup 19/ cm/sup -3/ (800 AA thick) in a 90- mu m-diameter device, with ideality factors of 1.0 and 1.4 for the base-collector and emitter-base junctions, respectively, demonstrating the excellent regrowth-interface quality. For a base doping of 10/sup 20/ cm/sup -3/ (400 AA thick), the current gain decreased to 8.<
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