GaN vertical superjunction device structures and fabrication methods

A method for fabricating a vertical superjunction device, the method comprising:

• providing a III-nitride substrate of a first conductivity type;
• forming a first III-nitride epitaxial layer of the first conductivity type coupled to the III-nitride substrate;
• forming a second III-nitride epitaxial layer coupled to the first III-nitride epitaxial layer;
• forming a third III-nitride epitaxial layer of the first conductivity type coupled to the second III-nitride epitaxial layer;
• removing a portion of the third III-nitride epitaxial layer and a portion of the second III-nitride epitaxial layer to expose a sidewall of the second III-nitride epitaxial layer and an exposed surface of the first III-nitride epitaxial layer;
• forming a masking material coupled to a surface of a remaining portion of the third III-nitride epitaxial layer;
• forming a fourth III-nitride epitaxial layer of the first conductivity type coupled to the sidewall of the second III-nitride epitaxial layer and the exposed surface of the first III-nitride epitaxial layer;
• forming a fifth III-nitride epitaxial layer of a second conductivity type coupled to the fourth III-nitride epitaxial layer;
• removing at least a portion of the masking material to expose:
• the surface of the remaining portion of the third III-nitride epitaxial layer,
• a surface of the fourth III-nitride epitaxial layer, and
• a surface of the fifth III-nitride epitaxial layer;
• and
• forming one or more insulating structures coupled to the fifth III-nitride epitaxial layer.