Termination structure for gallium nitride schottky diode

A nitride-based Schottky diode, comprising:

• a nitride-based semiconductor body of a first conductivity type;
• a first metal layer formed on a front side of the nitride-based semiconductor body forming a Schottky junction therewith, the first metal layer forming an anode electrode of the Schottky diode;
• a cathode electrode in electrical contact with the nitride-based semiconductor body;
• and
• a termination structure formed on the front side of the nitride-based semiconductor body and at an edge of the anode electrode, the termination structure being configured to reduce electric field crowding at the edge of the anode electrode, the termination structure comprising:
• a guard ring comprising a nitride-based epitaxial layer of a second conductivity type, opposite the first conductivity type, formed on the front side of the nitride-based semiconductor body at the edge of the first metal layer, part of the nitride-based epitaxial layer extending under the first metal layer, the nitride-based epitaxial layer having a step recess where the part of the epitaxial layer having a thinner thickness is disposed towards the Schottky junction of the Schottky diode;
• and
• a dielectric field plate formed on a top surface of the nitride-based epitaxial layer, the dielectric field plate extending at most to the step recess of the nitride-based epitaxial layer.