A thyristor semiconductor includes a first layer, located on a first surface of a substrate, where the first layer is a first P layer. A second layer, located on a second surface of the substrate, is a second P layer. The second surface is opposite the first surface. A third layer is located between the first layer and the substrate. An isolation region is located along an edge of the substrate The isolation region is adjacent the second P layer. An emitter, next to the third layer, is connected to a cathode.