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The dielectric response of epitaxial BaTiO3 thin films deposited on MgO was measured through surface electrodes as a function of applied bias, frequency, and temperature. The room temperature value of the dielectric constant was ∼500 with a dissipation factor, tan(δ), of 0.05 at 100 kHz. Measurements varying the bias field showed hysteresis of the dielectric response and a tunability of 30% for a maximum applied field of ∼7 MV/m. The frequency response of the dielectric constant is well described by a Curie–von Schweidler power law with an exponent ∼0.04 in the range 1 kHz–13 MHz. The films undergo a diffuse phase transition at temperatures higher than the bulk Curie temperature. The behavior of the dielectric response is attributed to the presence of residual strain in the epitaxial thin films.

We report on a thin-film channel waveguide electro-optic modulator fabricated in epitaxial BaTiO 3 on MgO. Films had an effective dc electro-optic coefficient of r eff ϳ50Ϯ5 pm/V and r eff ϳ18Ϯ2 pm/V at 5 MHz for ϳ1.55 m light. Extinction ratios of 14 dB were obtained. The electro-optic effect decreases to ϳ60% of the dc value at 1 Hz, 50% of the dc value at 20 kHz, and ϳ37% of the dc value at 5 MHz.

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Luminescence quenching in Er-doped epitaxial BaTiO3 thin films was investigated. From transient photoluminescence, nonradiative decay processes were measured, and a nonradiative resonant energy transfer model was developed. The nonradiative transition rate is linearly proportional to the OH impurity concentration in the films, indicating it is responsible for the observed quenching behavior.