A semiconductor device includes: a semiconductor region having charge carriers of a first conductivity type; a transistor cell in the semiconductor region; a semiconductor channel region in the transistor cell and having a first doping concentration of charge carriers of a second conductivity type, wherein a transition between the semiconductor channel region and the semiconductor region forms a first pn-junction; a semiconductor auxiliary region in the semiconductor region and having a second doping concentration of charge carriers of the second conductivity type. A transition between the semiconductor auxiliary region and semiconductor region forms a second pn-junction positioned deeper in the semiconductor region as compared to the first pn-junction. The semiconductor auxiliary region is positioned closest to the semiconductor channel region as compared to any other semiconductor region having charge carriers of the second conductivity type and that forms a further pn-junction with the semiconductor region.