High-speed InGaAs/InP composite collector bipolar transistors

The authors describe a composite collector bipolar transistor structure capable of high-speed and high breakdown voltage (BV/sub CEO/). The structure uses a composite collector of InGaAs and InP. f/sub T/=120 GHz at V/sub CE/=1.5 V at a current density of 77 kA/cm/sup 2/ were obtained. The breakdown voltage BV/sub CEO/ is greater than 5 V, and the output conductance is essentially independent of the collector voltage. Microwave transistors with an emitter size of 3*10 mu m/sup 2/ were fabricated by a self-aligned process. Microwave measurements were made from 100 MHz to 40 GHz as a function of the collector current and V/sub CE/. The authors have also fabricated and tested transimpedance amplifiers based on the composite collector transistors.