Reduction of Leakage Current in GaN Schottky Diodes Through Ultraviolet/Ozone Plasma Treatment

Surface passivation is critically important to improve the leakage current and current on/off ratio in Schottky diodes and thus the overall device performance and reliability. In this work, we report the reduction of leakage current in Pt/n-GaN and Pd/n-GaN Schottky diodes by improving metal-GaN interface passivation using ultraviolet/ozone (UV/O-3) plasma treatment. X-ray photoelectron spectroscopy was used to verify the improved passivation at the surface of GaN. Capacitance-voltage measurements were employed to determine the change in built-in potentials and the Schottky barrier heights of the Schottky diodes. Temperature-dependent measurements of current-voltage characteristics verified the thermionic emission carrier injection mechanisms. It was found that the leakage current in the GaN Schottky diodes was reduced by three orders of magnitude and the current on/off ratio was increased by two orders of magnitude due to the interface passivation that reduced defect states at metal-semiconductor interfaces and suppressed dislocation-induced leakage current.