In some embodiments, an apparatus comprises a semiconductor layer doped with a first-type dopant, a first region doped with the first-type dopant, a second region doped with the first-type dopant, and a third region doped with a second-type dopant, where the second-type dopant is opposite the first-type dopant. The first, second, and third regions are non-overlapping and are formed in the semiconductor layer. The third region is positioned between the first region and the second region. The apparatus also comprises a plurality of Zener implant regions buried in the semiconductor layer and the third region, where each of the plurality of Zener implant regions is configured to generate a different pinch-off region.