Techniques are disclosed for forming Schottky diodes on semipolar planes of group III-nitride (III-N) material structures. A lateral epitaxial overgrowth (LEO) scheme may be used to form the group III-N material structures upon which Schottky diodes can then be formed. The LEO scheme for forming III-N structures may include forming shallow trench isolation (STI) material on a semiconductor substrate, patterning openings in the STI, and growing the III-N material on the semiconductor substrate to form structures that extend through and above the STI openings, for example. A III-N structure may be formed using only a single STI opening, where such a III-N structure may have a triangular prism-like shape above the top plane of the STI layer. Further processing can include forming the gate (e.g., Schottky gate) and tied together source/drain regions on semipolar planes (or sidewalls) of the III-N structure to form a two terminal Schottky diode.