Submicron transferred-substrate heterojunction bipolar transistors

We report submicron transferred-substrate AlInAs/GaInAs heterojunction bipolar transistors (HBT's). Devices with 0.4-mu m emitter and 0.4-mu m collector 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 collector series resistance through the use of a Schottky collector contact, and from partial screening of the collector-base capacitance by the collector space charge.