Low turn-on voltage GaAs heterojunction bipolar transistors with a pseudomorphic GaAsSb base

We have developed GaAs heterojunction bipolar transistors (HBTs) with low t urn-on voltage by using pseudomorphic GaAsSb as the base layer. The turn-on voltage of GaAs/GaAs0.91Sb0.09 HBT is 0.10 V lower than that of InGaP/GaAs HBT. The lower turn-on voltage is attributed to the smaller band gap of th e GaAsSb base layer, indicating that GaAsSb is useful material for reducing turn-on voltage of GaAs HBTs. The current gain of 20 is obtained for GaAs/ GaAs0.91Sb0.09 HBT, which is larger than those of previously reported GaAs/ GaAsSb HBTs owing to the pseudomorphic, fully strained GaAsSb with no misfi t dislocations. The knee voltage of 0.47 V is attained at the collector cur rent density of 5x10(4) A/cm(2). These results indicate that GaAs/GaAsSb HB Ts have a great potential for reducing operating voltage and power dissipat ion. (C) 2001 American Institute of Physics.