An electrochemical surface treatment has been developed that decreases the reverse-bias leakage current in Schottky diodes fabricated on GaN grown by molecular-beam epitaxy (MBE). This treatment suppresses current flow through localized leakage paths present in MBE-grown GaN, while leaving other diode characteristics, such as the Schottky barrier height, largely unaffected. A reduction in leakage current of three orders of magnitude was observed for Schottky diodes fabricated on the modified surface compared to diodes fabricated on the unmodified surface for reverse-bias voltages as large as −20 V. In addition to suppressing reverse-bias leakage, the surface treatment was found to improve substantially the ideality factor of the modified surface diodes compared to that of unmodified surface diodes, suggesting that such a surface modification process could be useful for a variety of GaN-based electronic devices.

Miller, E. J., Schaadt, D. M., Yu, E. T., Waltereit, P., Poblenz, C., & Speck, J. S. (2003). Reverse-bias leakage current reduction in GaN Schottky diodes by electrochemical surface treatment. Applied Physics Letters, 82(8), 1293–1295.