Performance enhancement of composition graded base type-II InP/GaAsSb DHBT with fT>500 GHz

[[abstract]]The high frequency performance of type-II InP/GaAsSb double heterojunction bipolar transistors (DHBTs) with compositionally graded and uniform 25 nm base layers and 65 nm InP collectors is investigated. The graded base DHBT achieves a peak current gain of 20.5 compared to 14.9 for the uniform base DHBT at current densities near 15 mA/μm2. The peak fT of a graded base device with 0.38×8 μm2 emitter dimensions improves from 505 GHz at 25 °C to 535 GHz at −55 °C as determined by −20 dB/decade extrapolation. The base grading has reduced the total transit time by 25% compared to the uniform base type-II DHBT.[[fileno]]2030161010016[[department]]電機工程學