Preparation and characterization of epitaxial LiNbO3 thin films by metal-organic chemical vapor deposition

LiNbO3 thin films were prepared on sapphire substrates by the metal-organic chemical vapor deposition (MOCVD) technique, using lithium dipivaloylmetha nate [Li(DPM)] and niobium pentaethoxide [Nb(O-C2H5)(5)] precursors. LiNbO3 mms were deposited on (001) and (012) sapphire substrates and their crysta lline structures were investigated by X-ray diffraction and pole figure ana lyses. The LiNbO3 alms deposited on (001) sapphire substrates showed strong (001) orientation involving twin structures, and highly (100)-oriented fil ms were obtained on the (012) sapphire substrates. The full width at half m aximum (FWHM) of the X-ray rocking curves of (001)-oriented and (100)-orien ted LiNbO3 films were, respectively, 0.16 degrees and 0.21 degrees. Field e mission scanning electron microscope (FE-SEM) analysis showed that highly ( 100)-oriented LiNbO3 films had unique morphologies with long and narrow gra ins. The grains align in plane on the (012) sapphire substrate, and the c-a xis of the LiNbO3 film is parallel to the short axis of the grains.