InP/GaAsSb/InP double heterojunction bipolar transistors with high cut-off frequencies and breakdown voltages

In this work, we report on the DC and microwave performance of MOCVD-grown carbon-doped InP/GaAsSb/InP double heterojunction transistors (DHBTs) with various collector thicknesses. The cut-off frequencies (and breakdown voltages) are 106 GHz (8 V), 82 GHz (10 V) and 40 GHz (15 V) for the 2000 Å, 3000 Å and 5000 Å, lightly doped collectors. The 106 GHz, which is the best f_T ever reported in this material system, is obtained while maintaining a relatively high breakdown voltage (BV_CEO=8 V). The lower cut-off frequencies obtained for the 3000 Å and 5000 Å, collectors are attributed to the longer transit time in the collector and also to the Kirk like limitation brought about by high current densities in the thicker collectors