Dresden 2011 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 1: Dielectric and ferroelectric thin films 1

DF 1.5: Vortrag

Montag, 14. März 2011, 12:00–12:20, MÜL Elch

Comparative study of ferroelectric properties in Langmuir-Blodgett and spin-coated thin films of poly(vinylidene fluoride/trifluoroethylene) copolymers — •Manfang Mai, Bjoern Martin, and Herbert Kliem — Institute of Electrical Engineering Physics, Saarland University, Campus Building A5 1, D-66123, Saarbruecken, Germany

Poly(vinylidene fluoride/trifluoroethylene) copolymer thin films were prepared by Langmuir-Blodgett technique with thickness d ranging from 37 to 139nm and spin coating method (d=53-327nm). Their ferroelectric behavior has been investigated and compared by polarization switching measurements. Both kinds of films exhibit almost the same switching behaviour with varying thicknesses. As sample thickness reduces, the hysteresis loops tend to slant and the switching transients become broader. The coercive field increases with decreasing sample thickness, whereas the remanent polarization is nearly independent of sample thickness. The switching time decreases with increasing field and it is independent of thickness down to 69nm in LB films and 71nm in spun films. Slower switching is observed for a thickness below 60nm in both LB films and spun films. This could be due to the depolarization field induced by the surface oxidation layers of Al electrodes which becomes the more pronounced the thinner the sample is. The switching voltage suggests thin films in the range of 60-100nm are promising candidates for technical applications.