NOVEL ALGAAS/GAAS HETEROJUNCTION BIPOLAR-TRANSISTORS FABRICATED BY 2-STAGE MOLECULAR-BEAM EPITAXY

Abstract

Two-stage molecular beam epitaxy (MBE) growth was employed to fabricate AlGaAs/GaAs heterojunction bipolar transistors (HBTs) for the first time. Due to the unique base contact layer design, the base can be made very thin without increasing the extrinsic base sheet resistance and the etching of the base contact can be done very easily and very reliably. In addition, the base-collector separation layer design contributed to the reduction of parasitic capacitance. D.C. differential current gains up to 110 and 200 were obtained for 1000 and 500 angstrom base width, respectively.