Fabrication of high-breakdown GaN Schottky barrier diodes over deeply-etched crystal surfaces

We report in this paper an effective method to recover the defects on GaN surfaces following inductively coupled-plasma (ICP) deep-etching using KOH treatment with optimized concentration. GaN Schottky barrier diodes are fabricated over the unintentionally doped GaN buffer region of LED epi-wafers with this method, which achieves a high breakdown over 200 V as revealed in our measurement. This was accompanied with a dramatically reduced leakage current by four orders of magnitude. Temperature-variable current-voltage characterization of the fabricated Schottky junctions and the subsequent carrier transport analysis indicate that the surface concentration of the n-type dopants reduces by more than 20-folds, confirming the effectiveness of the KOH treatment in removing the ICP-induced surface defects.