Temperature dependence of collector breakdown voltage and output conductance in HBT's with AlGaAs, GaAs, InP, and InGaAs collectors

The common-emitter I-V characteristics were measured over the temperature range of 25-125 degrees C for HBTs (heterojunction bipolar transistors) with different semiconductor band-gap collectors. For In/sub 0.53/Ga/sub 0.47/As collectors, the low band-gap (0.75 eV at 25 degrees C) results in high leakage currents and low collector breakdown voltages which actually decrease with increasing temperature. In contrast, wide band-gap GaAs and AlGaAs collectors exhibit low leakage currents and high collector voltages which increase with increasing temperature. It is demonstrated that the use of an In/sub 0.53/Ga/sub 0.47/As/InP heterojunction collector results in near ideal I-V characteristics with high collector breakdown voltages (>10 V from 25-125 degrees C).<
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