Effect of hydrogen annealing treat on the recrystallization of the β-Ga2O3 grains fabricated by chemical vapor deposition

β-Ga 2 O 3 material with wide band gap and high radiation resistance, is potential in the application of X-ray radiation detections, and UV photoelectric detectors. The detector properties, such as sensitivity, response speed and stability, strong depend on the crystal quality of β-Ga 2 O 3 material. In this paper, β-Ga 2 O 3 thin films composed of crystalline grains were fabricated on sapphire substrates using the chemical vapor deposition technique. The thin films underwent annealing treatment in oxygen and a mixed ambient (5% H 2 +95% Ar), respectively. The effects of annealing on the structural, surface morphological and optical properties were investigated. X-ray photoelectron spectroscopy indicated the oxygen vacancy concentration decreased after annealing treatment. Overall, the β-Ga 2 O 3 thin films annealed in the hydrogen ambient displayed the best recrystallization characteristics, the process was discussed. The role of hydrogen quietly differed to oxygen during the annealing treatment, hydrogen promoted the decomposition of β-Ga 2 O 3 grains, followed by regrowth of β-Ga 2 O 3 with a preferred orientation, where decomposition and regrowth occurred competitively. The crystalline grains presented a gradual increase in size from as-grown to O 2 -annealed and H 2 -annealed β-Ga 2 O 3 thin films. Meanwhile, the grains annealed in hydrogen displayed a distinct alignment. The epitaxial relationships between the β-Ga 2 O 3 thin films and the sapphire substrate were investigated. Photoluminescence and absorption spectra were measured, the emission peaks fitted by Gaussian functions, and the deduced optical bandgap indicated the influence of the annealing treatment on the recrystallization of β-Ga 2 O 3 .