Functional oxide thin films are getting more and more attention due to their unique dielectric, piezoelectric, ferroelectric, magnetic, superconducting properties. This thesis focuses on the growth, compositional control, and structure-property relationships of SrTiO₃ and Na_0.5K_0.5NbO₃ thin films. These films were prepared by rf reactive magnetron sputtering. Structure-property investigations were performed by Rutherford backscattering spectroscopy, high resolution x-ray diffraction, scanning electron microscopy, atomic force microscopy, transmission electron microscopy methods, and dielectric, ferroelectric and piezoelectric measurements. Information from the structure­property relationship studies was then used as input to improve the quality and properties of the thin-layers. High quality SrTiO₃ and Na_0.5K_0.5NbO₃ films suitable fortunable microwave dielectric components were developed. SrTiO₃ thin films with relatively high dielectric constant were also deposited on commercial substrates for the goal of integrating by-pass capacitors into multi-module chips. Ferroelectric and piezoelectric properties of Na_0.5K_0.5NbO₃ thin films were also studied for the technological goal of fabricating piezoelectric sensors. The relative materials performance characteristics of these films under important operational variables as devices were also tested.

Epitaxial (001) orientated SrTiO₃ films have been deposited on LaA1O₃(001) substrates using off-axis sputtering. Stoichiometric targets yielded 20 % Sr-deficient films, whereas Sr-enriched targets (Sr_1.1 Ti_0.9O_3.0) resulted in stoichiometric films. For stoichiometric SrTiO₃ film the domain structure of the substrate was exactly copied into the film as revealed by the ω-ω/20 map and ω-Φ maps. On the other hand Sr deficient film exhibited a large degree of mosaicity. The lattice parameters of the stoichiometric films were also smaller than the Sr-deficient ones and closer to the bulk value. The dielectric properties of the stoichiometric films were superior to the Sr-deficient films.

To further investigate the influence of deposition conditions on film composition and structure, SrTiO₃ thin films have also been grown on LaA1O₃(001) byon-axis sputtering. Epitaxial growth of SrTiO3 films on LaA1O₃(001) single crystal substrates has been realized at growth temperatures as low as 350 °C. In the growth temperature range below 350 °C, films are polycrystalline showing three different orientations (100), (110), and (111).

Utilizing high dielectric constant thin film for integrated capacitors is one important factor in downsizing microelectronic devices and systems. In the present work SrTiO₃ thin films have been grown on Cu-coated glass fiber laminate substrates at ambient temperature. The obtained films have low crystallinity. The dielectric constants of the films were found to spread between 40-70 and the dissipation factors decreased with frequency down to 8x10^-4 at 1 MHz.

Room temperature tunable dielectric thin films are attractive for many types ofmicrowave components in telecommunication industry. For this purpose Na_0.5K_0.5NbO₃ thin films have been grown on LaA1O₃(001) substrates. XRD showed that the films are epitaxial of good quality (mosaic broadening as narrow as 0.044°). The dielectric properties of these interdigital capacitors were measured at 1 MHz from roomtemperature down to 50 K. The capacitor showed a high tunability (35 %) at room temperature and a low loss tangent of 0.007 without de bias applied.