Pseudomorphic AlInP/InP heterojunction bipolar transistors

Novel InP-based heterojunction bipolar transistors (HBTs) using an AlInP pseudomorphic emitter, together with an InP base and collector, have been fabricated. By using InP as both base and collector, the advantage of high electron velocity and high breakdown field of InP collectors are obtained without the problem associated with the energy barrier between the more standard InGaAs/InP base and collector heterojunction. Epitaxial layers were grown by gas-source molecular beam epitaxy (GSMBE). The 200 Å pseudomorphic emitter had an aluminium fraction of 15%, sufficiently suppressing hole injection from the base. The DC gain for 40×40 μm² devices reached 18. The breakdown voltage BV_CEO of 10 V is an improvement over devices with InGaAs base and collector layers