PdGe on GaAs: A study of the applicability in InGaP/GaAs HBT fabrication

Recently InGaP/GaAs HBTs have demonstrated performance comparable to AlGaAs/GaAs and have proven to be well suited for high-speed and low-noise applications. Despite the excellent performance of InGaP/GaAs HBTs, continued efforts towards reducing the delay associated with the emitter resistance and capacitance are required. To help minimize the emitter resistance, PdGe contacts on n-type GaAs were studied. This experiment studies the behavior of the PdGe alloyed on a hot plate for times less than 30 minutes and compares results to RTA alloys. Also studied is the behavior of the PdGe contacts alloyed in various ambients. Finally, the issues associated with performing a self-aligned emitter etch with PdGe contacts are also discussed.