【Epitaxy Papers】Growth of a High-Quality α-Ga₂O₃ Thin Film on a-Plane Sapphire by Sol–Gel Spin Coating and Rapid Thermal Annealing

      Researchers from Chung-Ang University have published a dissertation titled " Growth of a High-Quality α-Ga₂O₃ Thin Film on a-Plane Sapphire by Sol–Gel Spin Coating and Rapid Thermal Annealing " in Surfaces and Interfaces.

Abstract

      α-Ga₂O₃ has attracted attention as a key material for next-generation power semiconductor devices and deep-ultraviolet optoelectronic devices owing to its widest energy bandgap (∼5.3 eV) and high critical electric field (∼9.5 MV/cm) among Ga₂O₃ polymorphs. In addition, α-Ga₂O₃ has a highly symmetric corundum structure, which is beneficial for oriented thin-film growth on sapphire substrates and bandgap engineering with other corundum-structured oxides. However, high-quality α-Ga₂O₃ thin films are typically grown by vapor-phase methods that require expensive equipment and stringent process control, limiting scalability to large-area production and mass manufacturing. In this study, high-quality α-Ga₂O₃ thin films with preferential (110) orientation were fabricated on a corundum-structured a-plane sapphire (110) substrate, which has a small in-plane lattice mismatch with α-Ga₂O₃, using a low-cost sol–gel spin coating process followed by rapid thermal annealing in an O₂ atmosphere. The effects of annealing temperature on the phase formation and the surface, optical, and chemical properties of the films were investigated, and a phase-pure α-Ga₂O₃ film was obtained at an optimized annealing temperature of 600°C, exhibiting a uniform surface morphology, high optical transmittance in the UV–visible region, and weak defect-related signatures in photoluminescence and X-ray photoelectron spectroscopy analyses. These results demonstrate that high-quality, (110)-preferentially oriented, pure α-Ga₂O₃ thin films can be realized on a-plane sapphire via simple, low-cost solution processing, providing evidence for process scalability and potential cost reduction of α-Ga₂O₃ thin-film technology and helping lower the barrier to commercialization of α-Ga₂O₃-based devices.

DOI：

https://doi.org/10.1016/j.surfin.2026.110280