Electrical Properties of Au/n-GaN Schottky Junctions with an Atomic-Layer-Deposited Al₂O₃ Interlayer

The temperature-dependent electrical properties of Au/GaN Schottky diodes with an Al₂O₃ layer prepared by using atomic layer deposition (ALD) were investigated. Compared to the Au/GaN junction, the Au/Al₂O₃/GaN junction was found to have lower barrier heights and higher ideality factors. For the Au/GaN junction, the native oxide and the thin surface barrier formed by surface states caused a large leakage current and a small capacitance. Due to surface passivation through the ALD process, the leakage current for the Au/Al₂O₃/GaN junction was reduced. The barrier height reduction for the Au/Al₂O₃/GaN junction was associated with interface dipole formation at the Al₂O₃/GaN interface.