InGaAs/InAlAs/InP collector-up microwave heterojunction bipolar transistors

Collector-up InGaAs/InAlAs/InP heterojunction bipolar transistors (HBTs) were successfully fabricated, and their DC and microwave characteristics measured. High collector current density operation (J/sub c/>30 kA/cm/sup 2/) and high base-emitter junction saturation current density (J/sub 0/>10/sup -7/ A/cm/sup 2/) were achieved. A cutoff frequency of f/sub t/=24 GHz and a maximum frequency of oscillation f/sub max/=20 GHz at a collector current density of J/sub 0/=23 kA/cm/sup 2/ were achieved on a nominal 5- mu m*10- mu m device.<
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