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M: Metallphysik

M 26: Nanoskalige Materialien I

M 26.2: Vortrag

Dienstag, 25. März 2003, 15:00–15:15, IFW D

Nanocharacterisation of oxide tunnelbarriers by atomprobe tomography — •Mario Kuduz¹ and Guido Schmitz² — ¹Institut für Materialphysik, D-37073 Göttingen — ²Institut für Materialphysik, D-48148 Münster

Tunnelbarriers (TMR) are currently of interest for application in sensors and storage devices. Compared to Giant Magneto Resistance (GMR) devices, tunnelbarriers are distinguished by an improved effect amplitude and a higher base resistivity, so that they may be used in ’current perpendicular to plane’ arrangements.
We investigate the nano-structure of such TMR devices using field ion microscopy in combination with a high atomic resolution 2D detection setup. TMR structures consisting of Co and Ni₇9Fe₂1 electrodes and Al₂O₃ barriers were prepared by sputter deposition on tips of only 30 to 50 nm curvature radius suitable for field ion microscopy. The 3D spatial distribution of the atomic species have been determined with sub-nanometer resolution. In particular, the dependence of the oxygen distribution on various deposition methods, i.e. deviations from the ideal stoichiometry within the barrier and partial oxidation of the metallic electrodes will be discussed.