Temperature dependence of common-emitter I-V and collector breakdown voltage characteristics in AlGaAs/GaAs and AlInAs/GaInAs HBT's grown by MBE

Temperature-dependent measurements from 25 to 125 degrees C have been made of the DC I-V characteristics of HBTs with GaAs and In/sub 0.53/Ga/sub 0.47/As collector regions. It was found that the GaAs HBTs have very low output conductance and high collector breakdown voltage BV/sub CEO/>10 V at 25 degrees C, which increases with temperature. In striking contrast, the In/sub 0.53/Ga/sub 0.47/As HBTs have very high output conductance and low BV/sub CEO/ approximately 2.5 V at 25 degrees C, which actually decreases with temperature. This different behavior is explained by the >10/sup 4/ higher collector leakage current, I/sub CO/, in In/sub 0.53/Ga/sub 0.47/As compared to GaAs due to bandgap differences. It is also shown that device self-heating plays a role in the I-V characteristics.>