Deposition and properties of ferroelectric (lead,strontium) titanium trioxide thin films for room temperature tunable microwave devices.

摘要

Our research implements a new candidate (Pb,Sr)TiO3 (PSTO) for tunable microwave applications at room temperature. PSTO thin films are deposited on different substrates such as LaAlO3 (LAO), NdGaO3 (NGO), and MgO by laser ablation deposition technique. Their structural properties are studied by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), and Rutherford Backscattering (RBS). The dielectric properties up to 20 GHz are measured by interdigital capacitor (IDC) technique. The results indicate that our PSTO films are highly epitaxially growth with excellent crystallinity. Large dielectric constant, high tunability and low dielectric loss indicate that our PSTO films are very promising for applications in room temperature tunable microwave devices.; Strain effects on the dielectric properties of PSTO films are studied. We observed the anisotropic dielectric properties in PSTO thin films on orthorhombic (110) NGO substrates, which are attributed to the anisotropic mismatch strains.; We found that the structural and dielectric properties of PSTO films are also dependent on the post-annealing methods. Their effects are strongly related to the strains induced by the different cooling processes.