Fabrication, Physical Properties and Microstructural Characterization of Nanostructured Ferroelectric Films

By using pulsed laser deposition method, nanostructured BaTiO3 ferroelectric films (with a thickness of 25 nm) were grown on Si substrates and coated by nanoporous alumina membranes (NAMs) with an average pore size of 25 nm. Metal Pt nanowires were embedded in NAMs as a part of the bottom electrode. The dielectric and ferroelectric properties, and microstructure of the nanostructured BaTiO3 films were characterized. The results show that the dielectric constant of the BaTiO3 nanofilms is decreased slowly from 196 to 190 as the increase of measured frequency from 103 Hz to 106 Hz, and their dielectric loss is increased slowly from 0.005 to 0.007 in the low frequency range from 103 Hz to 105 Hz, whereas quickly increased up to 0.013 at high frequencies over 105 Hz. The remanent polarization and the coercive field of the BaTiO3 nanofilms are 5 uC/cm2 and 680 kV/cm, respectively. Cross-sectional (scanning) transmission electron microscope (TEM) images demonstrate that the BaTiO3 nanofilms contact directly with the Pt nanowires, and the interface between them has some degree of waviness. Suitable post-annealing temperature is the critical processing parameter of fabricating nanostructured ferroelectric films as considering a trade-off between the ordered degree of metal nanowires within NAMs and the crystallinity of ferroelectric nanofilms.