High-performance microwave power AlInAs/GaInAs/InP double heterojunction bipolar transistors with compositionally graded base-collector junction

We report, for the first time, on the use of compositional grading at the base-collector (B-C) junction of AlInAs/GaInAs/InP double heterojunction bipolar transistors (HBT) to achieve high-performance devices for microwave power and analog circuit applications. To overcome the conduction band potential barrier at the B-C junction, we have inserted an n-GaInAs spacer and a novel 100 nm compositional grade between the GaInAs base and the wide bandgap InP Collector. A base-collector breakdown voltage of 32 V, collector-emitter breakdown voltage of 26 V, and a f/sub max/ of 93 GHz have been achieved. Preliminary power measurements at 10 GHz on 240 /spl mu/m/sup 2/ emitter DHBT's resulted in over 5 W/mm output power at a collector bias of 10 V.<
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