Relationship between defects and the dielectric and transport properties of SrTiO3 thin films

摘要

We report on some of the key properties of ferroelectric and high-permittivity thin films relevant for their application in metal/insulator/metal structures, such as voltage tunable capacitors and novel memories. We use a model system, Pt/SrTiO3/Pt thin film structures, with microstructures, stress states and point defects characterized by advanced transmission electron microscopy techniques, high-resolution x-ray diffraction and wafer curvature measurements. We investigate the relation between defects and dielectric properties, measured at frequencies up to 1 GHz. We discuss the origins of dielectric losses in these films and the role of point defects, such as oxygen vacancies. We report on dielectric deadlayers, which cause a significant reduction in the dielectric tunabilities. We discuss the influence of dielectric relaxation on the thermal leakage characteristics of textured and epitaxial Pt/SrTiO3/Pt thin film structures. We also discuss the properties of Pt/SrTiO3/Pt structures with ultrathin (5 ?? 10 nm) SrTiO3 films.