Influence of Nitrogen Annealing Treatment on Optical, Microstructural, and Chemical Properties of Ga2O3 Film Grown by Plasma-Enhanced Atomic Layer Deposition

In this paper, high-quality β-Ga2O3 films were grown on silicon substrates by plasma-enhanced atomic layer deposition (PEALD). Effects of annealing temperature on β-Ga2O3 thin films were studied. Atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray reflection (XRR), and ultraviolet (UV) emission spectroscopy were used to systematically characterize Ga2O3 thin films. AFM test results showed that as annealing temperature increased from 500 to 900 °C, the roughness of film increased from 0.542 to 1.58 nm. XPS test results showed that the concentration of oxygen vacancies in annealed films was significantly reduced. After annealing, the energy band of the film increased from 4.73 to 5.01 eV, and the valence band maximum (VBM) increased from 2.58 to 2.67 eV, indicating that the annealing treatment under a nitrogen atmosphere can improve the quality of films. Results demonstrate that high-quality Ga2O3 films can be obtained by the annealing process after atomic layer deposition (ALD). The proposed method can realize an ideal stoichiometric ratio of the Ga2O3 thin film as well as precise control of its optical, electrical, and microstructural properties. This work lays the foundation for future application of Ga2O3 materials in photoelectric detection, power devices, transparent electronics, and other fields.