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DF: Dielektrische Festkörper

DF 7: Dielektrische und ferroelektrische Schichten und Rastermethoden

DF 7.4: Vortrag

Donnerstag, 14. März 2002, 10:50–11:10, 11

Structural and dielectric properties of BaTiO₃/SrTiO₃-multilayers deposited by PLD — •Gerd Köbernik and Wolfgang Häßler — IFW Dresden, PF270016, 01171 Dresden

Due to the integration process of ferroelectric films in electronic circuits the film thickness becomes smaller and smaller. The characterization of thin films in the thickness range of lower than about 100nm has shown that the dielectric constant is decreasing with decreasing film thickness. The dielectric properties of such thin films are influenced by internal stresses which are caused by the lattice mismatch between film and substrat which are relaxing at thicker films by the formation of dislocations. At a special kind of thin films, the multilayers, the film stresses can be tuned by an additional parameter, the film periodicity.

In the framework of this contribution BaTiO₃ / SrTiO₃-superlattices with different thicknesses and periodicities are prepared by pulsed laser deposition on single crystalline SrTiO₃-substrates in (100) and (111) orientation as well as on Pt metallized Si-substrates. The structural and dielectric properties characterized by x-ray diffraction, TEM and dielectric measurements are compared with those of a (Ba_0,5Sr_0,5)TiO₃ solid solution. The thickness and temperature dependence of the dielectric constant is discussed in correlation to the stresses in the films.