Dresden 2003 – scientific programme
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DF: Dielektrische Festkörper
DF 8: Dielektrische und ferroelektrische Schichten, Nanostrukturen und Rastermethoden
DF 8.4: Talk
Thursday, March 27, 2003, 10:50–11:10, HSZ/403
Pz, σ, εsurface, and Uint determined in thin ferroelectric PZT films by piezoresponse force microscopy and pull-off force spectroscopy — •Lukas M. Eng1 and Kurt Franke2 — 1Institut für Angewandte Photophysik, Technische Universität Dresden, D-01069 Dresden, Germany, eng@iapp.de — 2Institut für Festkörper- und Werkstofforschung Dresden e.V., D-1171 Dresden, Germany
We report the very first experiments being able to determine the effective surface polarisation Pz, surface charge density σ, surface dielectric constant εsurface, and built-in electric voltage Uint in thin ferroelectric PZT films with a lateral resolution of < 50 nm. This becomes possible combining piezoresponse force microscopy (PFM) and pull-off force spectroscopy (PFS). Both methods are sensitive to the local electrostatic tip-sample interaction which, for ferroelectrics, arises from the spontaneous polarisation Pz and the mobile charge density σ present at the sample surface. While Pz and σ contribute additively in PFS, they are subtractive for PFM hence allowing the two contributions to be separated. εsurface and Uint finally are derived from an absolute matching of PFM and PFS results as well as fitting to a model. Results and implications for PZT will be discussed.