CHARACTERIZATION OF LITHIUM-NIOBATE THIN-FILMS DERIVED FROM AQUEOUS-SOLUTION

Lithium niobate (LiNbO3, LN) films prepared from aqueous precursor sol utions were characterized, in terms of the hydroxyl contents on the su rface layers through crystallization and optical properties. Approxina tely 98% of the hydroxyl residues on the surface layers of crystalline films were polymerized after heat treatment at 350 degrees or 500 deg rees C, whereas 50% of the hydroxyl residues remained on the surface l ayers of amorphous films heat-treated at 200 degrees C. Highly preferr ed oriented LN films had a tendency to consist of in-plane rotation by 60 degrees during nucleation and crystallization. Optical losses (at 632.8 mm) were 2 dB/cm in the TE0, mode and 4 dB/cm in the TM0 mode of the LN films (thickness of 670 mm) on sapphire (001) substrates prepa red from a neutralized precursor solution after annealing in oxygen at a temperature of 500 degrees C (where TE and TM are the transverse el ectric and magnetic modes, respectively).