Submicrometer fully self-aligned AlGaAs/GaAs heterojunction bipolar transistor

A novel submicrometer fully self-aligned AlGaAs/GaAs heterojunction bipolar transistor (HBT) for reducing parasitic capacitances and resistances is proposed. The fabrication process utilizes SiO2 sidewalls for defining base electrode width and separating this electrode from both emitter and collector electrodes. Measured common-emitter current gain beta for a fabricated HBT with 0.6 x 10-sq micron emitter dimension and 0.7 x 10-21 micron x 2 base dimension is 26 at 90,000 A/sq cm collector current density.