Method for fabricating a heterojunction bipolar transistor

A process for prodn. of a heterojunction bipolar transistor (HBT), with an overlying collector region and underlying base and emitter regions, involves (a) producing the emitter region by epitaxially growing the corresponding semiconductor layers (3, 4), selectively implanting insulating zones (7) in the emitter region and then carrying out a healing process; (b) depositing the base layer (8) and the collector layers (12, 13) by a second epitaxial growth process; and (c) producing the ohmic contacts (14, 15, 16). Pref. the emitter region is produced from a n-doped GaAs layer (3) and a n-doped AlGaAs or GaInP layer (4), followed by deposition of a GaAs protective layer (5), and the insulating zones (7) are produced, using an implantation mask, by implanting oxygen ions at 10 -10 cm. dose and at 100-200 keV ion energy.