Dresden 2009 – scientific programme
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DS: Fachverband Dünne Schichten
DS 26: Poster II
DS 26.33: Poster
Wednesday, March 25, 2009, 09:30–12:30, P5
VUV Ellipsometry of BiFeO3 thin films grown by pulsed-laser deposition — •Cameliu Himcinschi1, Ionela Vrejoiu2, Li Ding1, Marion Friedrich1, Cristoph Cobet3, Norbert Esser3, Marin Alexe2, and Dietrich R.T. Zahn1 — 1Chemnitz University of Technology, Semiconductor Physics, D-09107 Chemnitz, Germany — 2Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle, Germany — 3Institute for Analytical Sciences, Department Berlin, D-12489 Berlin, Germany
The interest in ferroelectric and magnetoelectric multiferroic epitaxial films arises from their interesting properties and is stimulated by the potential applications in non-volatile ferroelectric memories or novel multiple state memories and devices based on magnetoelectric effects. Epitaxial thin films of bismuth ferrite, BiFeO3, were deposited by pulsed laser deposition (PLD) on Nb-doped SrTiO3 (100) and DyScO3 (110) substrates, at Tg=650∘C and 0.14 mbar O2. Ellipsometry is a non-destructive and very sensitive surface and thin film measurement technique which can determine film thickness, surface roughness and dielectric properties of such materials with a very high precision. These materials absorb in the UV close to the end of the energy domain available in commercial ellipsometers, while the VUV range is hardly explored at all. By means of the BESSY ellipsometer, the complex dielectric constant of BiFeO3 films is determined up to 9.8 eV. The optical gap of BiFeO3 was determined to be 2.77 eV from a linear extrapolation of the (αE)2 to zero in the plot: (αE)2 vs. energy.1
1 A. Kumar et. al, Appl. Phys. Lett. 92, 121915 (2008)