Microstructure and Dielectric Properties of Textured SrTiO 3 Thin Films

We investigate the relationship between microstructure and dielectric properties of textured SrTiO 3 thin films deposited by radio‐frequency magnetron sputtering on epitaxial Pt electrodes on sapphire substrates. The microstructures of Pt electrodes and SrTiO 3 films are studied by transmission electron microscopy, atomic force microscopy, and X‐ray diffraction. SrTiO 3 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 SrTiO 3 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 SrTiO 3 on tensile substrates will have a higher Curie–Weiss temperature and a greater dielectric constant than (110)‐oriented films or bulk SrTiO 3 . 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.