Structure and electrical properties of Ga2O3 thin films grown by atomic layer deposition on Ru and TiN electrodes

Abstract

The composition, structure, and electrical properties of Ga₂O₃ thin films, grown by atomic layer deposition (ALD) from GaI₃ and O₃ precursors, were characterized. The films were deposited on Si substrates and on Ru and TiN bottom electrodes at temperatures of 200–500 °C. Growth of κ- and ε-Ga₂O₃ was observed on Ru and TiN at substrate temperatures ≥ 325 °C, while temperatures ≥ 425 °C were needed to deposit crystalline Ga₂O₃ on bare Si. The formation of both ε-Ga₂O₃ and predominant κ-Ga₂O₃ phases in crystalline films was confirmed by high-resolution transmission electron microscopy studies. Films deposited at 375–450 °C exhibited low leakage current densities (down to 10⁻⁹ A cm⁻² at an electric field strength of 0.1 MV cm⁻¹), breakdown fields up to 6.5 MV cm⁻¹, and permittivity values up to 22 at 10 kHz. These results demonstrate that Ga₂O₃ deposited in this ALD process is suitable for implementation as high permittivity dielectrics in advanced electronic devices. Furthermore, the findings highlight the importance of deposition temperature and substrate choice in optimizing the dielectric properties of Ga₂O₃ films deposited for these applications.