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DF: Fachverband Dielektrische Festkörper

DF 10: Nano- and microstructured dielectrics

DF 10.4: Vortrag

Mittwoch, 16. März 2011, 11:40–12:00, MÜL Elch

Nonlinear Optics on Inversion-Domain Nanostructures in Fe₂O₃(ZnO)_m — •Thomas Lottermoser¹, Simon Eichhorn², Werner Mader², and Manfred Fiebig¹ — ¹HISKP, University of Bonn, Germany — ²Institute of Inorganic Chemistry, University of Bonn, Germany

We prepared surfaces of ZnO single crystals with thin layers of Fe₂O₃ on top. Diffusion of Fe³⁺ ions generates a layer with the composition Fe₂O₃(ZnO)_m with small m≈ 15 at the surface of the ZnO single crystal. Investigation with transmission electron microscopy reveals that in this layers regular patterns of triangular shaped ZnO inversion domains on a nanometer scale are formed by self organization. Additional measurements with electron energy loss spectroscopy show that the Fe³⁺ ions form monolayers at the domain boundaries while the domains itself consist of pure ZnO. The size of the inversion domains can be tuned by controlling the concentration of the Fe³⁺ ions.

These type of nano-structured materials has the potential to exhibit new magneto-optical properties that are tunable in various ways, e.g., by the Fe³⁺ concentration, the structure size and orientation of the iron-’doped’ layers. The periodic and spatial inversion symmetry breaking nature of this compounds makes nonlinear optics an obvious characterization tool. Here, we report on our first experiments using optical second-harmonic generation (SHG). We observed an enhancement of the SHG intensity by about one order of magnitude compared to bulk ZnO. Polarization analysis indicates that this enhancement can be attributed to the meta-structure of the doped layers.