InAlGaAs/InGaAs HBT

We trial-produced InAlAs/InGaAs HBT (heterojunction bipolar transistor) and InAlGaAs/InGaAs HBT changing the base thickness from 1500 A to 4000 A. As a result, we clarified that many high energy electrons injected from the emitter reach the collector high electric field region with their high energy intact, and if the injection energy is high, those electrons deteriorate collector current saturation characteristics by generating impact ionization, not in the emitter side base region but in this high electric field region. In addition, in trial-production of InAlGaAs/InGaAs HBTs for which injection energy is restricted for the purpose of improving the collector current saturation characteristics, we obtained f/sub T/=50 GHz, although it is a rather large size device having an emitter-base junction area of 20 um/sup 2/, a base-collector junction area of 220 um/sup 2/, and a base thickness of 1500 A. Further, according to these trial-productions, we were able to propose a InAlAs/InGaAs/InP DHBT which allows near-ballistic action.<
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