Preparation and Characterization of Epitaxial LiNbO₃ Thin Films by Metal-Organic Chemical Vapor Deposition

LiNbO 3 thin films were prepared on sapphire substrates by the metal-organic chemical vapor deposition (MOCVD) technique, using lithium dipivaloylmethanate [Li(DPM)] and niobium pentaethoxide [Nb(O–C 2 H 5 ) 5 ] precursors. LiNbO 3 films were deposited on (001) and (012) sapphire substrates and their crystalline structures were investigated by X-ray diffraction and pole figure analyses. The LiNbO 3 films deposited on (001) sapphire substrates showed strong (001) orientation involving twin structures, and highly (100)-oriented films were obtained on the (012) sapphire substrates. The full width at half maximum (FWHM) of the X-ray rocking curves of (001)-oriented and (100)-oriented LiNbO 3 films were, respectively, 0.16° and 0.21°. Field emission scanning electron microscope (FE-SEM) analysis showed that highly (100)-oriented LiNbO 3 films had unique morphologies with long and narrow grains. The grains align in plane on the (012) sapphire substrate, and the c -axis of the LiNbO 3 film is parallel to the short axis of the grains.