Investigation of barium titanate thin films on MgO substrates by second-harmonic generation

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Abstract
Barium titanate (BaTiO3) thin films grown by the metalorganic chemical vapor deposition (MOCVD) technique on MgO substrates have been investigated by second‐harmonic generation at an incident wavelength of 1.064 μm. Transmission electron microscopy was used to show that substrate quality and pretreatment (annealing) has a strong influence on microstructure and optical properties of these films due to nucleation effects during MOCVD growth. Angular dependence of second‐harmonic signal indicates both a‐ and c‐textured growths in this film/substrate system. Stress‐induced stabilization appears to determine the orientation of the microcrystallites in the films. Corona poling does not result in a preferred orientation of the film. Effective d coefficients as high as 2.13 pm/V have been obtained from as‐grown films.