Abstract: The invention relates to a semiconductor device (10) with a substrate (11) and a semiconductor body (12) comprising a vertical bipolar transistor with an emitter region, a base region and a collector region (1, 2, 3) of, respectively, a first conductivity type, a second conductivity type opposite to the first conductivity type and the first conductivity type, wherein the collector region (3) comprises a first sub-region (3A) bordering the base region (2) and a second sub-region (3B) bordering the first sub-region (3A) which has a lower doping concentration than the second sub-region (3B), and the transistor is provided with a gate electrode (5) which laterally borders the first sub-region (3A) and by means of which the first sub-region (3A) may be depleted.

Abstract: The invention relates to a semiconductor device (10) with a substrate (11) and a semiconductor body (12) comprising a vertical bipolar transistor with an emitter region, a base region and a collector region (1, 2, 3) of, respectively, a first conductivity type, a second conductivity type opposite to the first conductivity type and the first conductivity type, wherein the collector region (3) comprises a first sub-region (3A) bordering the base region (2) and a second sub-region (3B) bordering the first sub-region (3A) which has a lower doping concentration than the second sub-region (3B), and the transistor is provided with a gate electrode (5) which laterally borders the first sub-region (3A) and by means of which the first sub-region (3A) may be depleted.

Abstract: The invention relates to a semiconductor device with a heterojunction bipolar, in particular npn, transistor with an emitter region (1), a base region (2), and a collector region (3), which are provided with respectively a first, a second, and a third connection conductor (4, 5, 6), while the bandgap of the base region (2) is lower than that of the collector region (3) or of the emitter region (1), for example owing to the use of a silicon-germanium alloy instead of pure silicon. Such a device is very fast, but its transistor shows a relatively low BVceo. In a device according to the invention, the emitter region (1) or the base region (2) comprises a sub-region (1B, 2B) with a reduced doping concentration, which sub-region (1B, 2B) is provided with a further connection conductor (4B, 5B) which forms a Schottky junction with the sub-region (1B, 2B). Such a device results in a transistor with a particularly high cut-off frequency fT but with no or hardly any reduction of the BVceo.