A 277-GHz f/sub max/ transferred-substrate heterojunction bipolar transistor

We report a AlInAs-GaInAs transferred-substrate heterojunction bipolar transistor (HBT). The transferred-substrate process permits fabrication of narrow and aligned collector-base and emitter-base junctions, reducing the collector-base capacitance and increasing the device f/sub max/. A device with aligned 0.7-/spl mu/m emitter and 1.6-/spl mu/m collector stripes has extrapolated 277 GHz f/sub max/ and 127 GHz f/sub /spl tau//, respectively.