【Epitaxy Papers】Epitaxial Deposition of β-Ga₂O₃ Films by Radio-Frequency Magnetron Sputtering at Elevated Substrate Temperatures

      Researchers from the Dagestan State University have published a dissertation titled "Epitaxial Deposition of β-Ga₂O₃ Films by Radio-Frequency Magnetron Sputtering at Elevated Substrate Temperatures" in Vacuum.

Abstract

      In this work, we demonstrate for the first time the epitaxial growth of β-Ga₂O₃ thin films on (0001) sapphire substrates by radio-frequency magnetron sputtering at elevated substrate temperatures of 1000–1200 °C. To overcome the problem of inefficient heating of infrared-transparent sapphire under vacuum, a thin tantalum backside layer was introduced, ensuring uniform thermal conditions required for epitaxy. Structural analysis (XRD, RHEED) confirmed a monodomain epitaxial orientation with low mosaicity and high crystalline order, while atomic force microscopy revealed a smooth surface with a root-mean-square roughness of ∼1.9 nm, consistent with a two-dimensional growth regime. Raman spectroscopy exhibited well-resolved β-Ga₂O₃ phonon modes shifted relative to reference values, indicating a coherently strained lattice. The optical bandgap was determined to be ∼5.0 eV, exceeding that of bulk β-Ga₂O₃, which can be attributed to tensile strain and possible Al incorporation from the sapphire substrate. These findings establish a new technological route to obtain high-quality epitaxial β-Ga₂O₃ films by radio-frequency magnetron sputtering, making them highly attractive for solar-blind photodetectors, ultraviolet optoelectronics, and power electronic devices.

DOI：

https://doi.org/10.1016/j.vacuum.2025.114840