Improving Ni/GaN Schottky diode performance through interfacial passivation layer formed via ultraviolet/ozone treatment

Electrical passivation has a significant effect on metal-semiconductor (MS) device operations including performance and reliability. In this study, the improvement in performance of Ni/GaN Schottky diodes (SDs) through an ultraviolet/ozone (UV/O-3) interface treatment is investigated and the mechanism of carrier conduction at the MS junction interfaces is analyzed. The formation of surface oxide layer at the MS interface through the UV/O-3 treatment is confirmed by the measurements using X-ray photoelectron spectroscopy, contact angle, and atomic force microscopy. The atomic intensity and surface energy increased and surface roughness improved through the implementation of oxide layer. Electrical measurements reveal reduced leakage and improved breakdown voltage and are used to determine the Schottky barrier height and Richardson constant of the Ni/GaN MS SDs. The enhancement in the entire performance of the MS SDs is attributed to the passivation of defect centers at the dislocation-related pits through the formation of oxide layer with the UV/O-3 treatment, which thereby improves the carrier transfer properties of Ni/GaN SDs.