Effect of oxygen flow ratio on crystallization and structural characteristics of gallium oxide thin films

Beta-gallium oxide (beta-Ga2O3) thin films were prepared on a MgO (100) substrate under different oxygen flow ratios via magnetron sputtering. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and UV-visible near-infrared (UV-vis-NIR) analyses were conducted to study how the oxygen flow ratio affected the crystalline quality and the surface topography of the films. Microstructure analysis revealed a clear out-of-plane orientation of beta-Ga2O3 (100) || MgO (100). The film deposited under an oxygen flow ratio of 1% presented the optimal single-crystalline structure, while excess oxygen was confirmed to negatively impact the crystallization characteristics of the films. SEM measurements indicated that the increase in the oxygen flow ratio reduced the grain size and RMS roughness. The average transmittance of the beta-Ga2O3 films in the visible range exceeded 83%, with a broad luminescence band exhibited at approximately 485 nm in the photoluminescence (PL) spectra.

Automated summary

Beta-gallium oxide (beta-Ga2O3) thin films were prepared on a MgO (100) substrate under different oxygen flow ratios via magnetron sputtering and their crystalline quality and surface topography were studied using various analyses. The films exhibited an out-of-plane orientation with the optimal single-crystalline structure achieved under a 1% oxygen flow ratio. Excess oxygen was found to negatively impact the crystallization characteristics of the films, reducing grain size and roughness. The films demonstrated high transmittance in the visible range and exhibited a broad luminescence band at approximately 485 nm in the photoluminescence spectra.