Berlin 2008 – wissenschaftliches Programm

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SYNF: Symposium Ferroic materials and novel functionalities

SYNF 1: Ferroic materials and novel functionalities I

SYNF 1.1: Vortrag

Dienstag, 26. Februar 2008, 10:30–10:45, A 151

Characterization of ultra thin epitaxial BaTiO₃ films on Pt(111): A LEED, STM and XPS study — •Stefan Förster and Wolf Widdra — Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, Halle

Ultra thin epitaxial BaTiO₃ films have been grown on a Pt(111) single crystal substrate by r.f. magnetron sputtering and characterized by LEED, STM and XPS. The BaTiO₃ films were deposited at room temperature under a pressure of about 2.5·10⁻³ mbar of Argon (80 %) and Oxygen (20 %) gas mixture and subsequently annealed in UHV. The magnetron sputtered films exhibit a high reproducibility of film thickness and composition. XPS spectra of the films are in good agreement with spectra of a BaTiO₃(111) single crystal, indicating that the films grow with BaTiO₃ stoichiometry. The weakening of the XPS signal from the Pt substrate was used to estimate the film thickness in the range up to several nm. Annealing to temperatures above 900 K leads to highly ordered films which are stable up to 1250 K. Their LEED pattern show several different structures depending on the preparation conditions which includes the (√3×√3) structure known from the BaTiO₃(111) single crystal surface. Atomically resolved STM images confirm the √3 structure. Additionally, they show the growth of extended flat islands with diameters up to 200 nm separated by steps of multiple unit cell heights. These BaTiO₃ films might be ideal playground for future investigations of multiferroic systems.