Bipolar transistor

A bipolar transistor comprising:

• a collector region (25, 25a) of a first conduction type (n);
• a subcollector region (10;
• 10a, 10b) of the first conduction type (n+), which is electrically connected to the collector region (25, 25a) at a first side of the collector region (25, 25a);
• a base region (30) of the second conduction type (p) which is provided at a second side of the collector region (25, 25a);
• an emitter region (50) of the first conduction type (n+) which is provided above the base region (30) on the side remote from the collector region (25, 25a) and
• a carbon-doped semiconductor region (10;
• 10a;
• 24, 24a) which is provided on the first side alongside the collector region (25, 25a);
• characterized in that the carbon-doped semiconductor region (10;
• 10a;
• 24, 24a) has a carbon concentration of 1019-1021 cm−3;
• the base region (30) has a smaller cross section than the collector region (25, 25a) and the collector region has, in the overlap region with the base region (30), a region (25a) having an increased doping compared with the remaining region (25);
• and the carbon-doped semiconductor region ( . . . ) prevents an outdiffusion from the zone (25a) of the collector region into the remaining region (25) of the collector region.