Improved breakdown of AlInAs/InGaAs heterojunction bipolar transistors

AlInAs/InGaAs heterojunction bipolar transistors exhibiting DC breakdown voltages, V_ceo, in excess of 7 V are reported. The layer structure uses a two-stage collector to achieve the high breakdown voltages. The devices are fabricated with a triply selfaligned dry etch process with high yield. Respective f_T and f_max values of 80 and 60 GHz are obtained for emitter dimensions of 2*4 mu m². The combination of layer structure design and processing yields AlInAs/InGaAs with both DC and RF characteristics suitable for large-scale, high-speed digital circuit applications.