Dresden 2006 – scientific programme

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O: Oberflächenphysik

O 29: Poster session II (Nanostructures, Magnetism, Particles and clusters, Scanning probe techniques, Time-resolved spectroscopy, Structure and dynamics, Semiconductor surfaces and interfaces, Oxides and insulators, Solid-liquid interfaces)

O 29.71: Poster

Wednesday, March 29, 2006, 14:30–17:30, P2

Growth and morphology of ZnO on Fe(110) — •Christian Tusche, Holger L. Meyerheim, and Jürgen Kirschner — MPI für Mikrostrukturphysik Halle, D-06120 Halle, Germany

The Fe/ZnO/Fe tri-layer system is a potentially promising system for tunneling magneto-resistance (TMR) and future spintronic applications. Since the tunneling properties sensitively depend on the details of the interface[1], the study of the growth, morphology and structure of ZnO on Fe and vice versa is of primary importance.

Ultrathin films of ZnO were deposited on Fe(110) from a ZnO-rod heated by electron bombardment and by pulsed laser deposition using a stoichiometric ZnO target. For the ZnO(0001)/Fe(110) epitaxy the lattice mismatch is 12% for [1 1 2 0]_ZnO ∥ [0 0 1]_Fe. ZnO films up to 3 monolayers thickness exhibit a (1x1) pattern in low energy electron diffraction (LEED), although with reduced spot sharpness as compared to the clean Fe(110) surface. Structural order improves upon annealing to 520K, however at higher temperatures, the interface is subject to a reduction-oxidation reaction. Scanning tunneling microscopy on films in the same thickness range reveals a two dimensional growth of the ZnO.

For ZnO-deposition in ambient oxygen atmosphere (p(O₂)=10⁻⁷ mbar) photo electron spectroscopy in indicates an oxidation of the Fe substrate. This goes in parallel with the observation of extra spots in the LEED-pattern, indicative for a relaxed ZnO adlayer (hexagonal a-axis = 3.25 Å).

[1] C. Tusche et al., Phys. Rev. Lett. 95 (2005) 176101