Vertical GaN p–n diode with deeply etched mesas by contactless photo-electrochemical etching

Abstract GaN p–n diodes were fabricated by contactless photo-electrochemical (PEC) etching, and their electrical characteristics were evaluated. A high vertical etching rate of 80 nm min −1 , which is usable for device fabrication etching processes, was achieved using a H₃PO₄ based electrolyte containing S₂O₈ 2 ⁻ ions and intense UV light. The sidewalls after etching were perpendicular to the substrate owing to the directivity of UV light. Vertical GaN p–n diodes with deeply etched mesas were fabricated by contactless PEC etching and avalanche breakdown was confirmed. The results point to an alternative method of fabricating high-performance GaN power devices.