Polycrystalline BaTiO3 thin films with thickness ranging from 2100 to 20 000 Å were prepared on platinum substrates using off-axis radio-frequency magnetron sputtering. The variation in room temperature permittivity of the films was investigated with respect to thickness using x-ray diffraction and transmission electron microscopy. All films were ferroelectric and their room temperature permittivity, which was significantly higher than previously reported values, showed a strong dependence on film thickness. Higher permittivity was attributed primarily to the presence of ferroelectric domains. The room temperature permittivity of the thin films showed large variations with grain size, as in the case of BaTiO3 ceramics. The increase in permittivity with increasing film thickness was attributed to the decrease in defect concentration with grain growth. The 20 000 Å film showed an abrupt decrease in permittivity and the presence of an intergranular phase having titanium-excess composition; these phenomena are discussed in terms of domain boundary pinning and recrystallization.

The number of isolated Mn2+ ions and Mn2+ clusters in ZnS:Mn powder and thin films has been studied using Mn2+ spectra measured at room temperature with an X-band electron-paramagnetic-resonance spectrometer. While the concentration of the isolated Mn2+ ions decreases with increasing Mn concentration, the concentration of the clusters increases. At low Mn concentration, the Mn2+ ion substitutes for the Zn ion in ZnS:Mn in the cubic phase. At high Mn concentrations, where the ZnS powder has a dominant hexagonal phase, the Mn ion still prefers to substitute for Zn in ZnS:Mn at the cubic site rather than at the hexagonal site.

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A new deposition method used to prepare BaTiO3 thin films resulted in multilayered structure with higher dielectric constant, capacitance per unit area, and breakdown strength than those prepared by a conventional stacking method; the new method continuously decreased the substrate temperature after initial deposition of a polycrystalline BaTiO3 layer. The observed high dielectric constant could be explained only by a multilayered amorphous/microcrystalline/polycrystalline structure, the nature of which was confirmed by scanning electron microscopy and index of refraction measurement. Well-defined ferroelectric hysteresis loops were observed as well with insignificant leakage current effects.