Patent ID: 8592903

Claim:
A bipolar semiconductor device, comprising: a first metallization; and a diode structure comprising a forward current flow direction, the diode structure comprising: a first semiconductor region of a first conductivity type, the first semiconductor region adjoining the first metallization, the first semiconductor region being electrically coupled with the first metallization and comprising a first doping concentration; a second semiconductor region of a second conductivity type comprising a second doping concentration and forming a first pn-junction with the first semiconductor region, the first pn-junction being forwardly biased when a forward current flows through the diode structure; at least a third semiconductor region of the first conductivity type electrically coupled with the first metallization and comprising a third doping concentration which is higher than the first doping concentration, the first semiconductor region and the third semiconductor region forming an interface; and at least a fourth semiconductor region of the second conductivity type at least partially embedded in the third semiconductor region such that at least one of the first semiconductor region and the third semiconductor region is arranged between the second semiconductor region and the fourth semiconductor region, wherein the fourth semiconductor region comprises a fourth doping concentration which is higher than the second doping concentration, and wherein the fourth semiconductor region forms a second pn-junction with the third semiconductor region, the fourth semiconductor region being arranged to inject charge carriers at least into the third semiconductor region during at least one of commutation and switching off of the forward current.