Fachbereich 11 - Physik
Institut für Materialphysik
Nanoanalysis of Interreactions

Structural transformation of oxide tunnel barriers under electrical overloa

The project explores the possibilities to analyse the atomic distribution of oxide tunnel barriers by atomprobe tomography. This method had been proven to yield a local chemical analysis with outstanding spatial resolution at conductive metallic specimens. The successful application to oxides would be a great progress. For the experiments Co/Al₂O₃/NiFe triple layers has been deposited on top of tungsten substrate tips. The oxide barrier, having a thickness of 1.5 nm, were produced by various techniques, which let to different oxygen contents inside the barrier. With these thin layers embedded in metal matrix, indeed successful measurements were possible. Stoichiometric composition were found with sputtering under at least 10^-4 mbar partial pressure of oxygen, while the a-posteriori oxidation in an oxygen atmosphere of natural pressure yielded oxygen depleted barriers.

Drittmittelgeber:

Deutsche Forschungsgemeinschaft (SFB 602)

Beteiligte Wissenschaftler:

M. Kuduz, R. Kirchheim (Univ. Göttingen), G. Schmitz (Projektleiter)