High-Gain Low Turn-On Voltage AlGaAs/GaAsNSb/GaAs Heterojunction Bipolar Transistors Grown by Molecular Beam Epitaxy

AlGaAs/GaAsNSb heterojunction bipolar transistors (HBTs) with low turn-on voltage have been fabricated. The turn-on voltage of the device fabricated from an as-grown sample is ~180 mV lower than that of a conventional AlGaAs/GaAs HBT. The effect of rapid thermal annealing on device performance is an increase in the gain from ~8.5 to ~20. However, the knee voltage of the annealed sample (~3 V), as well as the turn-on voltage, is also higher compared with that of the as-grown sample (~1.5 V).