Semiconductor device

A semiconductor device comprising:

• a collector layer of a first conductivity type;
• a base layer of a second conductivity type disposed above the collector layer;
• an emitter layer of the first conductivity type disposed above the base layer, and having a mesa structure such that, in a direction intersecting a stacking direction of the collector layer and the base layer, a width of the emitter layer is narrower than a width of the base layer;
• a collector electrode electrically connected to the collector layer;
• an emitter electrode electrically connected to the emitter layer;
• a base electrode electrically connected to the base layer;
• and
• a surface recombination prevention layer disposed between the emitter layer and the base layer, and having a structure different from the base layer and the emitter layer, wherein
• the base layer has one surface that faces the emitter layer,
• the one surface has an emitter-layer facing portion that faces the emitter layer in the stacking direction, a base-electrode facing portion that faces the base electrode in the stacking direction, and a region located between the emitter-layer facing portion and the base-electrode facing portion, and
• the surface recombination prevention layer is disposed to cover the region of the one surface.