Influence of Oxygen on Ga2O3 Deposition at Low Temperature by MOCVD

In this study, thin films of Ga 2 O 3 were fabricated on sapphire substrates utilizing metal–organic chemical vapor deposition technology, with deposition conducted at a temperature of 400 °C. The investigation focused on examining the influence of oxygen on the surface morphology, phase transition, and optical characteristics of Ga 2 O 3 films synthesized at relatively low temperatures. X-ray diffraction tests indicated that all films were polycrystalline and had mixed β and ε phases. With an increase in oxygen flow rate from 1400 to 1800 sccm, β-Ga 2 O 3 became the dominant material. Atomic force microscope analysis showed that the root-mean-square roughness had decreased. Film thicknesses, as measured by scanning electron microscopy, were 285.3, 257.6, 243.2, and 254.2 nm, respectively. The high-resolution transmission electron microscope confirmed a mixed-phase structure at an oxygen rate of 2100 sccm. Moreover, the X-ray photoelectron spectroscopy results show that increasing the oxygen flow rate from 1400 to 1800 sccm is effective in reducing the oxygen vacancies and defects in the films. However, excessive oxygen flow (2100 sccm) leads to the exacerbation of prereaction and the deterioration of the film’s crystalline quality.