SOL-GEL DERIVED EPITAXIAL LINBO3 THIN-FILMS FOR OPTICAL WAVE-GUIDES

LiNbO3 thin films for optical waveguides have been epitaxially grown o n Al2O3 substrate by sol-gel process using lithium ethoxide, niobium p entaethoxide and 2-methoxyethanol. The epitaxial growth of LiNbO3 thin films was obtained with non-hydrolytic conditions in the sol-gel proc ess. In order to improve the quality of LiNbO3 thin films for optical waveguide applications, the growth of MgTiO3 thin films as a buffer la yer was investigated by sol-gel method. Epitaxial growth of MgTiO3 thi n films was also obtained using magnesium acetylacetonate and titanium isopropoxide in the sol-gel process. At non-hydrolytic conditions, Mg TiO3 thin films were epitaxially grown at crystallization temperatures of 700-800 degrees C. Subsequently, highly oriented LiNbO3 thin films were,grown on MgTiO3/Al2O3. Epitaxial nature of LiNbO3/Al2O3, MgTiO3/ Al2O3 and LiNbO3/MgTiO3/Al2O3 was examined by XRD normal scan and pole figure measurements. It was found that thin buffer layer of MgTiO3 wa s required to obtain highly oriented LiNbO3/MgTiO3/Al2O3.