Patent ID: 7109567

Claim:
A semiconductor device comprising a semiconductor body ( 10 ) of silicon with a substrate ( 11 ) and a semiconductor layer structure of silicon, which structure comprises a bipolar transistor having an emitter region ( 1 ) of a first conductivity type, a base region ( 2 ) of a second conductivity type opposed to the first conductivity type and with a germanium content between 10 and 30 at %, and a collector region ( 3 ) of the first conductivity type having a first, a second, and a third doping concentration, respectively, and having a first, a second, and a third connection conductor ( 4 , 5 , 6 ), respectively, the base region ( 2 ) comprising a semiconductor material whose bandgap is lower than that of the material of the collector region ( 3 ) or of the emitter region ( 1 ), wherein the emitter region ( 1 ) or the base region ( 2 ) comprises a strongly doped portion and a sub-region ( 1 B, 2 B) that has a lower doping concentration, the sub-region ( 1 B, 2 B) having a further connection conductor ( 4 B, 5 B) which together with the sub-region ( 1 B, 2 B) forms a Schottky junction and the strongly doped portion forms an ohmic contact with the first or second connection conductor.