Dresden 2017 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 11: Ferroics - Domains, Domain Walls and Skyrmions II

DF 11.6: Vortrag

Mittwoch, 22. März 2017, 11:15–11:30, WIL B321

Controlling the intrinsic polarization state in RF sputtering grown ferroelectric ultrathin films — •Christian Weymann, Céline Lichtensteiger, Stéphanie Fernandez, Jean-Marc Triscone, and Patrycja Paruch — DQMP, University of Geneva, Geneva, Switzerland

Ferroelectric ultrathin films are technologically promising. Crucial to all applications is their intrinsic polarization state. To maintain a uniform polarization state, the depolarizing field must be compensated either by external free charges or by internal mobile charges from within the ferroelectric itself. The built-in field also affects the polarization state, as it favors one polarization direction over the other. It results from an asymmetry in the screening or from internal sources, such as trapped charges or strain gradients leading to flexoelectricity.

We show that we can manipulate both these fields, acting on the electrostatic boundary conditions via the use of dielectric spacer layers to increase the depolarizing field, or modulating the built-in field through changes in the growth temperature of PbTiO3 thin films.

Quality and production costs are also major issues for applications. Off-axis radio frequency (RF) magnetron sputtering is a reliable technique to grow these structures. However, the relatively low cost of such a system compared to other thin film deposition techniques traditionally brings the disadvantage of lower control over the sample quality. Here we present a slow kinetics intermittent sputtering (SKIS) approach which greatly enhances the sample quality, opening a pathway towards an affordable method to grow high quality epitaxial thin films.