Synthesis of monoclinic structure gallium oxide film on sapphire substrate by magnetron sputtering

Abstract

Gallium oxide (Ga₂O₃) films were deposited on singlecrystalline sapphire (0001) substrate by radio frequency (RF) magnetron sputtering technique in the temperature range of 300—500 °C. The microstructure of the β-Ga₂O₃ films were investigated in detail using X-ray diffractometer (XRD) and scanning electron microscope (SEM). The results show that the film prepared at 500 °C exhibits the best crystallinity with a monoclinic structure (β-Ga₂O₃). Structure analysis reveals a clear out-of-plane orientation of β-Ga₂O₃ (2̅01) ǁ Al₂O₃ (0001). The average transmittance of these films in the visible wavelength range exceeds 90%, and the optical band gap of the films varies from 4.68 eV to 4.94 eV which were measured by an ultraviolet-visible-near infrared (UV-vis-NIR) spectrophotometer. Therefore, it is hopeful that the β-Ga₂O₃ film can be used in the UV optoelectronic devices.