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 x 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.