Improved performance of lateral β-Ga2O3 Schottky barrier diodes by nitrogen thermal annealing

Abstract

We report the growth of $\left(\overline{2}01\right)$β-Ga₂O₃ ​epilayers on sapphire substrates using metalorganic chemical vapor deposition (MOCVD) and the fabrication of lateral Schottky barrier diodes (SBDs). Ti/Al/Ni/Au layers with respective thicknesses of 20/300/40/50 nm were deposited as the ohmic electrodes, followed by the deposition of 50/50 nm Ni/Au layers as the Schottky electrodes in lateral SBDs. The performance and characteristics of the SBDs were evaluated using I-V measurements and breakdown analysis. X-ray photoelectron spectroscopy analysis revealed that a high concentration of oxygen vacancies on the epilayer surface degraded the contact quality between the electrodes and β-Ga₂O₃, resulting in reduced current conduction at high bias, higher reverse leakage, and premature breakdown due to defects. To address these issues, rapid thermal annealing (RTA) treatment under nitrogen ambience was performed at 550 °C, 650 °C, and 750 °C temperatures for 60 s after ohmic electrode deposition to enhance SBD performance by improving contact quality and reducing interface defects. The RTA treatment reduced the proportion of oxygen vacancies, leading to significant improvements in SBD characteristics. The on-off current ratio increased from 5.56 × 10⁴ to 1.30 × 10⁷ in addition to the breakdown voltage 173 V to 263 V. These results demonstrate the critical role of RTA treatment under nitrogen ambience in optimizing β-Ga₂O₃-based SBDs and highlight its potential for next-generation power electronics.