【International Papers】Improved Heteroepitaxy of κ-Ga₂O₃ on c-plane Sapphire by Initial Mist Flow Stabilization during Mist Chemical Vapor Deposition

      Researchers from the University of Michigan have published a dissertation titled "Improved Heteroepitaxy of κ-Ga₂O₃ on c-plane Sapphire by Initial Mist Flow Stabilization during Mist Chemical Vapor Deposition " in Thin Solid Films.

Abstract

      Kappa-phase gallium oxide (κ-Ga₂O₃) is a metastable gallium oxide polymorph and an ultrawide bandgap semiconductor with potential applications in various electronic and optoelectronic devices. In this study, we present the effect of mist flow stabilization during the initial stages of mist chemical vapor deposition process on the crystal quality of heteroepitaxial thin films of κ-Ga₂O₃ grown on c-plane sapphire. Two κ-Ga₂O₃ films were grown using the same growth parameters with the only differing factor being the stabilization of the initial mist flow. Structural and optical properties of the films were characterized. Both processes resulted in epitaxial growth; however, controlling the initial mist flow leads to an improved Ga₂O₃/Al₂O₃ interface and superior crystal quality. The film grown with regulated mist flow exhibited an optical bandgap of 4.93 eV, a smooth surface with a root mean square roughness of 1.56 nm and a rocking curve full-width half-maximum value of 0.17°. Also, Ti/Au deposition on κ-Ga₂O₃ results in an interface resembling that of β-Ga₂O₃ and Ti/Au, explaining previous reports of ohmic behavior between κ-Ga₂O₃ and Ti/Au contacts.

Paper Link：https://doi.org/10.1016/j.tsf.2024.140223