A semiconductor device comprises a substrate, a cathode, an outer ring, an anode, an electrically insulating layer, and an electrically conducting layer. The substrate includes a semiconducting material having a first conduction type. The substrate has a first face and a second face substantially parallel to the first face. A cathode is disposed at the second face and has the first conduction type. An outer ring, having the first conduction type, is disposed at an outer perimeter of the first face of the substrate. An anode, having the second conduction type, is disposed at the first face of the substrate within an inner perimeter of the outer ring. An electrically insulating layer is disposed over the outer ring. An electrically conducting layer is disposed over the electrically insulating layer and over the outer ring. The electrically conducting layer electrically is insulated from the outer ring by the electrically insulating layer.