Research on the structural and optical stability of Ga2O3 films deposited by electron beam evaporation

Ga2O3 films were deposited on c-plane sapphire substrates using electron beam evaporation method with subsequent annealing in oxygen ambient for different time interval. The effect of annealing treatment on the microstructures and optical characteristics of Ga2O3 films were systematically investigated by X-ray diffraction, atomic force microscope, photoluminescence (PL) spectra and optical transmittance spectra, respectively. The results indicated that Ga2O3 films showed a stronger preferred orientation after annealing for 30, 60 and 90 min at 1,000 A degrees C. The diffraction peaks and (403) of the annealed Ga2O3 films increased first and then decreased. We discussed the influence of annealing time interval on the grain sizes and surface morphologies properties of Ga2O3 films. The PL spectra measured at room temperature revealed blue, green and red emissions. Intense green luminescence was obtained from the sample annealed for 60 and 90 min. The crystalline quality of Ga2O3 film was markedly improved after annealing, which caused the intensity of blue peak (similar to 430 nm) and green peak (similar to 513 nm) increasing noticeably. The origin of these emissions was discussed. All annealed Ga2O3 films exhibited a steep absorption edge in deep ultraviolet region, and presented over 70 % transmittance in the visual light region.