GaAs/AlGaAs heterojunction emitter-down bipolar transistors fabricated on GaAs-on-Si substrate

GaAs/AlGaAs heterojunction bipolar transistors with emitter-down structure were fabricated on GaAs-on-Si substrate for the first time. A maximum current gain of 25 was measured at a collector current density of 6250 A/cm². This value is comparable with that from similar devices fabricated on GaAs substrates. This result, along with previous work on large-scale integration of emitter-down transistors, demonstrates the potential for high-level integration of bipolar devices on GaAs-on-Si substrates.