Tailoring Ga2O3 Epitaxial Films on Sapphire: Impact of Gallium Ligand Precursors and Growth Temperature Using Mist-CVD

Abstract

Gallium oxide (Ga₂O₃) is emerging as a next-generation power semiconductor due to its wide bandgap of 5.0 eV. The mist chemical vapor deposition (Mist-CVD) technique offers a cost-effective approach to grow epitaxial Ga₂O₃ films, allowing precise control over chemical compositions and phases without the need for vacuum systems. This study investigates the influence of different gallium precursors: namely Ga(acac)₃, GaBr₃, and GaI₃; and varying growth temperatures on the heteroepitaxial growth of Ga₂O₃ films on c-plane (0006) sapphire substrates using Mist-CVD. The crystallinity and phase composition of the Ga₂O₃ films were found to be strongly dependent on both the ligand structure of the precursor and the deposition temperature. X-ray diffraction (XRD) analysis revealed the presence of α-phase (006), ε-phase (002), (004), (006), (008), and β-phase (2¯01), (4¯02), (6¯03), (8¯04) orientations in Ga₂O₃ films deposited at temperatures ranging from 500 °C to 700 °C, with the optimal phase formation varying according to the precursor used. X-ray photoelectron spectroscopy (XPS) results indicated that Ga₂O₃ films grown using gallium halide precursors exhibited lower carbon-related binding energies and fewer C-O bonds, suggesting that these carbon-free precursors are ideal for producing high-quality Ga₂O₃ epitaxial films. This study provides valuable insights into the epitaxial growth mechanisms of metal oxide semiconductors using the Mist-CVD method. Our work focuses on advancing the development of Ga₂O₃ material growth and its applications in device technology.