We investigate the relationship between microstructure and dielectric properties of textured SrTiO3 thin films deposited by radio‐frequency magnetron sputtering on epitaxial Pt electrodes on sapphire substrates. The microstructures of Pt electrodes and SrTiO3 films are studied by transmission electron microscopy, atomic force microscopy, and X‐ray diffraction. SrTiO3 films grown on as‐deposited and annealed Pt electrodes, respectively, consist of a mixture of (111)‐ and (110)‐oriented grains. Temperature‐dependent dielectric measurements show that differences in texture and microstructure are reflected in the Curie–Weiss behavior of the SrTiO3 films. Phenomenological models that account for the effects of thermal mismatch strain on the dielectric behavior are developed for different film textures. The models predict that at a given temperature, paraelectric (111)‐oriented films of SrTiO3 on tensile substrates will have a higher Curie–Weiss temperature and a greater dielectric constant than (110)‐oriented films or bulk SrTiO3. The experimental dielectric behavior is compared with the predictions from theory, and different contributions, such as interfacial layers, film stress, and microstructure, to the Curie–Weiss behavior are discussed.

The microstructure and orientation relationships of epitaxial (111)-oriented SrTiO3 thin films grown by radio frequency magnetron sputtering on epitaxial (111)-oriented Pt/Ti electrodes on sapphire were investigated using x-ray diffraction, conventional and scanning transmission electron microscopy. We show that the epitaxial growth of (111)-oriented SrTiO3 films was promoted by thin Ti adhesion layers underneath the Pt electrode. The SrTiO3 films nucleated with two twin-related orientation variants, rotated by 180° about the 〈111〉 surface normal. The twin boundaries were oriented approximately normal to the film plane, but no strong preference for a specific boundary plane was observed. Growth mechanisms and the relationships to the dielectric properties are discussed.

Bi 2 Ti 2 O 7 thin films were grown by radio-frequency magnetron sputtering on bare and Pt-coated sapphire substrates at low substrate temperatures (∼200 °C). Postdeposition anneals were carried out at different temperatures to crystallize the films. Nearly phase-pure Bi2Ti2O7 thin films with the cubic pyrochlore structure were obtained at annealing temperatures up to 800 °C. Impurity phases, in particular Bi4Ti3O12, formed at higher temperatures. At 1 MHz, the dielectric constants were about 140–150 with a very small tunability and the dielectric loss was about 4×10−3. The dielectric loss increased with frequency. The dielectric properties of Bi2Ti2O7 films are compared to those of pyrochlore bismuth zinc niobate films.

The factors controlling low frequency (1 MHz) dielectric losses of textured SrTiO 3 thin films deposited by radio-frequency magnetron sputtering on platinized sapphire substrates were investigated. In particular, the influence of film texture, phase transformations, applied bias field, temperature and annealing atmospheres was studied. Films that were (111) textured showed a phase transformation at ~ 150 K, whereas films that were predominantly (110) oriented did not exhibit a phase transformation in the measured temperature range (100 K -300 K). Two major contributions to the dielectric losses were identified: a low temperature loss increase for the (111) oriented film, which could be suppressed by an applied bias field, and a loss peak at 2 50 K (at 1 MHz), which was strongly frequency dependent and likely associated with a relaxing defect. The low temperature loss mode was related to the appearance of a phase transformation and contributed to the dielectric losses even at temperatures that were more than 100 K above the phase transformation. In contrast to the leakage properties of the films, which were strongly dependent on annealing atmospheres, annealing under reducing conditions had no significant influence on any of the observed loss modes. Possible origins of the different loss contributions are discussed.3

Atomic resolution high-angle annular dark field (HAADF) imaging in scanning transmission electron microscopy was used to investigate the interface atomic structure of epitaxial, (111) oriented SrTiO3 films on epitaxial Pt electrodes grown on (0001) sapphire. The cube-on-cube orientation relationship of SrTiO3 on Pt was promoted by the use of a Ti adhesion layer underneath the Pt electrode. While a Ti-rich Pt surface was observed before SrTiO3 growth, HAADF images showed an atomically abrupt SrTiO3∕Pt interface with no interfacial layers. The SrTiO3 films contained two twin variants that were related by a 180° rotation about the ⟨111⟩ surface normal. HAADF images showed two different interface atomic arrangements for the two twins. The role of Ti in promoting (111) epitaxy and the implications for the dielectric properties are discussed.