Some exemplary embodiments of a semiconductor device using a III-nitride heterojunction and a novel Schottky structure and related method resulting in such a semiconductor device, suitable for high voltage circuit designs, have been disclosed. One exemplary structure comprises a first layer comprising a first III-nitride material, a second layer comprising a second III-nitride material forming a heterojunction with said first layer to generate a two dimensional electron gas (2DEG) within said first layer, an anode comprising at least a first metal section forming a Schottky contact on a surface of said second layer, a cathode forming an ohmic contact on said surface of said second layer, a field dielectric layer on said surface of said second layer for isolating said anode and said cathode, and an insulating material on said surface of said second layer and in contact with said anode.