Submicron transferred-substrate heterojunction bipolar transistors

We report submicron transferred-substrate AlInAs/GaInAs heterojunction bipo lar transistors (HBT's). Devices with 0.4-mu m emitter and 0.4-mu m collect or widths have 17.5 dB unilateral gain at 110 GHz, Extrapolating at -20 dB/ decade, the power gain cutoff frequency f(max) is 820 GHz, The high f(max) results from the scaling of HBT's junction widths, from elimination of coll ector series resistance through the use of a Schottky collector contact, an d from partial screening of the collector-base capacitance by the collector space charge.