【Epitaxy Papers】Strategic Oxygen Vacancy Control via Defect Engineering in β-Ga₂O₃ Using Rapid Thermal Annealing for Advanced Electronics

      Researchers from the Chung-Ang University have published a dissertation titled "Strategic Oxygen Vacancy Control via Defect Engineering in β-Ga₂O₃ Using Rapid Thermal Annealing for Advanced Electronics" in Optical Materials.

Abstract

      This study optimizes annealing conditions for minimizing oxygen vacancies in β-Ga₂O₃ thin films using Rapid Thermal Annealing (RTA) at various temperatures. The sol-gel-derived thin films were characterized by their crystallographic structure, chemical composition, surface morphology, and optical properties. X-ray diffraction (XRD) analysis confirmed the monoclinic β-phase structure, exhibiting a preferred orientation along the (−201) plane at an annealing temperature of 1100 °C. UV–vis spectroscopy showed high (>85 %) transmittance in all films as well as increased bandgap with fewer defects. X-ray photoelectron spectroscopy (XPS) showed that the O/Ga ratio reached ∼1.4 at 1100 °C, approaching the ideal stoichiometric value of 1.5, while oxygen vacancy decreased to 10.44 %. However, at 1200 °C, aluminum diffusion from the substrate became more pronounced, as confirmed by XPS analysis, revealing Al-related peaks and indicating interdiffusion into the β-Ga₂O₃ lattice. To examine the defect engineering, photoluminescence spectroscopy (PL) reveals distinct emission peaks at 325 nm, 365 nm, and 415 nm, with the 325 nm peak becoming dominant at higher temperatures. X-ray reflectometry (XRR) revealed a consistent thickness of approximately 100 nm across all samples, with the highest density observed at 1100 °C. Atomic force microscopy (AFM) showed spin-coating-induced ripples at lower temperatures and cracks from thermal mismatch at higher temperatures.

DOI：

https://doi.org/10.1016/j.optmat.2025.117389