Optical properties of nanocrystalline α-GaO(OH) thin films

alpha-GaO(OH) thin films obtained by the sol-gel process have been characterized. All x-ray diffraction study confirmed that the films were crystalline with orthorhombic structure. The average crystallite size of the thin films was about similar to 2-3 nm as revealed by transmission electron microscope and x-ray diffraction studies. The optical transparency of the film was about 95% in the visible region. The films exhibited all optical semiconducting band gap of 5.27 eV, which was Much higher than those of alpha-Ga2O3 and beta-Ga2O3. The type of the optical transition was determined: it was found to be allowed direct in nature. No degradation of the films was observed after more than a year of exposure to an ambient atmosphere.