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C-axis LiNbO3 epitaxial films have been grown on c-plane sapphire substrates by solid source metal-organic chemical vapor deposition (MOCVD) using the tetramethylheptanedionate sources, Li(thd) and Nb(thd)4. Stoichiometric LiNbO3 films were deposited from Li(thd)-rich source compositions. Rocking curve FWHM values as low as 0.044° were measured on films grown at 710 °C. Rocking curve peak widths became broader as films were grown at progressively lower substrate temperatures. Single prism coupling experiments revealed clearly visible optical waveguiding, with optical attenuation values as low as 2 dB/cm in the best films.

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The solid source MOCVD technique1,2, employing a single powder vaporization source composed of mixed beta-diketonate metalorganic compounds, has been used to grow thin films of a variety of electro-optic materials, including lithium niobate, strontium barium niobate, and potassium niobate. Results for potassium niobate films are quite preliminary, but indicate that a volatile potassium organometallic source can be synthesized which is useful for growing potassium niobate by MOCVD. High quality single phase (001) oriented strontium barium niobate films have been deposited which exhibit waveguiding behavior. The most extensive work has been done on lithium niobate, which has been deposited epitaxially on a variety of substrates. Oriented z-axis (001) films have been grown on c-axis sapphire with and without a (111) oriented platinum base electrode and on a bulk grown lithium niobate substrate. Films grown directly on c-axis sapphire at 700 C exhibit x-ray rocking curve linewidths as low as.044 degrees, nearly perfect in-plane orientation as determined by x-ray phi scans, and peak-to-peak surface roughness less than 40 Å. Optical waveguiding has been demonstrated by a single prism coupling technique on similar films 1175 – 2000 Å thick grown at 500 C, with optical losses of approximately 2 db/cm at 632.8 nm measured over 3.5 cm long films. Polarization vs. electric field measurements on 1100 Å thick films grown on platinum show a hysteresis loop indicating ferroelectric behavior.

Thin-film waveguides of LiNbO3 have been grown on Al2O3-c by off-axis rf magnetron sputtering. The films have been characterized optically by prism coupling measurements, crystallographically by x-ray diffraction, and morphologically by atomic force microscopy. We find that optical losses can be dominated by scattering from large outgrowths that litter the surface of the film. These outgrowths are c− grains imbedded in a c+ matrix. Although some grains nucleate c−, others have their polarity reversed from c+ to c− after nucleation. A model will be presented to explain the preferential nucleation of c+ grains on Al2O3-c. The c− grains grow much faster than the c+ ones because of attractive coulombic forces between the c− grains and the ionized Li and Nb species in the sputter plume.