In at least one general aspect, a method can include forming a plurality of first active pillars and a plurality of edge pillars in a first semiconductor layer including an active region and a termination region, and forming a second semiconductor layer on the first semiconductor layer. The method can include forming a plurality of second active pillars and a plurality of preliminary charge balance layers in the second semiconductor layer, and annealing the first and second semiconductor layers such that the plurality of first active pillars and the plurality of second active pillars are connected by diffusing impurities implanted into the plurality of first active pillars and the plurality of second active pillars.