Abstract: A bipolar transistor has a base with an epitaxial base layer and a raised base connection region which in a lateral direction in parallel relationship with the substrate surface encloses the emitter which is surrounded by a spacer of insulating material. The epitaxial base layer is raised in a heightwise direction perpendicularly to the substrate surface. An emitter of a T-shaped cross-sectional profile is separated laterally from the outer base portion by a spacer of insulating material. Its vertical bar of the T-shape adjoins with its lower end the inner base portion.