Microstructural and electrical properties of (Sr,Ba)Nb2O6 thin films grown by pulsed laser deposition

Strontium barium niobate thin films have been deposited by pulsed laser deposition on (111)-textured Pt films, p-doped Si(100) and Nb doped STO (SrTiO3) single crystals. The deposition parameters were optimized for obtaining phase pure (001)-oriented films from stochiometric targets. The samples were annealed in oxygen to improve top electrode adhesion and reduce oxygen vacancies. The SBN/substrate interfaces were investigated by means of TEM combined with EDAX chemical analysis. Growth on silicon resulted in the formation of a few nm thick SiO2 interface layer. Epitaxial growth has been obtained on STO. A broad relaxor-type or diffuse phase transition occurs around −50 °C well below the transition temperature of single crystals. A second dielectric anomaly is observed around 80 °C, which, however, disappears after annealing in O2. Above, the dielectric loss increases exponentially due to presumed leakage by ion conduction. Hysteresis loops at room temperature confirm relaxor-type behaviour with a saturation polarization of 18 μC/cm2 and a weak hysteresis with a coercive field of 50 kV/cm.