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.