Tailoring oxygen-vacancy concentration in Ga₂O₃ thin films through controlled post-annealing: Experimental correlation between defect chemistry, carrier transport, and dielectric response
DOI:
https://doi.org/10.54355/tbusphys/30070147.4.2.2026.0055Keywords:
β-Ga₂O₃ thin films, oxygen vacancies, post-annealing, Hall transport, dielectric spectroscopy, defect engineeringAbstract
The control of oxygen-vacancy concentration is essential for optimizing the electrical performance of wide-bandgap oxide semiconductors. This study investigates the influence of controlled post-deposition annealing on the structural, chemical, electrical, and dielectric properties of RF magnetron-sputtered β-Ga₂O₃ thin films. The films were annealed at 700 °C for 2 h in oxygen, air, and nitrogen atmospheres to tailor the concentration of oxygen-related defects without altering the crystal phase. Structural evolution was characterized by X-ray diffraction, field-emission scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy, while the electrical and dielectric responses were evaluated using Hall-effect measurements, temperature-dependent resistivity, impedance spectroscopy, and dielectric spectroscopy. The results demonstrate that oxygen annealing improves crystallinity, increases the average crystallite size from 24.8 to 32.9 nm, reduces lattice microstrain, and decreases the relative concentration of oxygen-vacancy-related defects by approximately 35%. These changes increase the Hall mobility from 18.6 to 28.7 cm² V⁻¹ s⁻¹ while reducing the electron concentration from 5.82 × 10¹⁷ to 3.94 × 10¹⁷ cm⁻³. In addition, oxygen-rich annealing increases the activation energy for electrical conduction, suppresses dielectric losses, and enhances the stability of the dielectric response over a wide frequency range. A consistent correlation between defect chemistry, lattice ordering, carrier transport, and dielectric polarization was established, demonstrating that oxygen-vacancy engineering provides an effective strategy for tailoring the multifunctional properties of β-Ga₂O₃ thin films for advanced electronic and optoelectronic applications.
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Copyright (c) 2026 Ruslan Kalibek, Daria Sopyryaeva
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