Structural and Electrical Properties of Si-Doped β-Ga2O3 Thin Films Deposited by RF Sputtering: Effects of Oxygen Flow Ratio and Post-Annealing Temperature

Beta-gallium oxide (β-Ga2O3) is a semiconductor with an ultra-wide bandgap, high optical transparency, and excellent electrical properties, which can be finely tuned for a wide range of electronic devices. This study optimized the process conditions for fabricating β-Ga2O3 thin films with desired electrical characteristics. β-Ga2O3 films were deposited on (100) Si substrates via RF magnetron sputtering with varying O2 flow rates and post-annealed at temperatures ranging from 600 °C to 800 °C. The structural and electrical properties of the films were analyzed using X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), and Hall effect measurements. The XRD results confirmed the formation of nanocrystalline β-Ga2O3, with variations in peak intensities and shifts observed based on O2 flow rates. The films exhibited carrier concentrations exceeding 5 × 1022 cm−3, mobilities ranging from 50 to 115 cm2/Vs, and resistivity around 1 × 10−6 Ω⋅cm. This study demonstrates that the electrical properties of β-Ga2O3 thin films can be modulated during the deposition and post-annealing processes. The ability to control these properties underscores the potential of β-Ga2O3 for advanced applications in high-performance high-power devices and optoelectronic devices such as deep ultraviolet photodetectors.