Improved structural and optical properties of β -Ga 2 O 3 films by face-to-face annealing

Face-to-face annealing (FTFA) technology has been used to investigate the structural and optical properties of β-Ga2O3 thin films. The scanning electron microscope (SEM) results show that the top β-Ga2O3 film by using FTFA technology has a flatter surface than that of the conventional annealed film; on the contrary, the bottom film appears noticeable cracks. X-ray diffraction (XRD) and Raman scattering spectrum (Raman) studies further indicate that the top β-Ga2O3 film has a higher crystal quality, while the preferred orientation of the bottom one has changed significantly. Compared with the conventional annealed β-Ga2O3 film, the average transmittance in the near-ultraviolet to visible region of the top β-Ga2O3 film increases up to 96.4%, whereas the bottom one dropped sharply to 86.6%. It is demonstrated that the FTFA technology could effectively improve the structural and optical properties of β-Ga2O3 films, which shows a great potential for fabrication of high-performance β-Ga2O3 films optoelectronic devices.