Regensburg 2000 – wissenschaftliches Programm
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AM: Magnetismus
AM 18: Magnetowiderstand II: Oxide und Tunnelmagnetowiderstand
AM 18.9: Vortrag
Donnerstag, 30. März 2000, 11:30–11:45, H10
Optical and in-situ characterization of plasma oxidized Al for magnetic tunnel junctions — •Patrick LeClair, Jürgen Kohlhepp, Bart Smits, Henk Swagten, Bert Koopmans, and Wim de Jonge — Department of Applied Physics, Eindhoven University of Technology, The Netherlands
An optical polarization modulation technique was adapted to provide a simple, fast, and flexible method for optimizing tunnel barrier fabrication and studying the kinetics and growth characteristics of tunnel barriers, using AlOx as an example. The optical technique allows precise determination of the amount of remaining metallic Al as a function of the initial Al thickness, while scanning a laser spot across the wedge. Optical data suggest that the oxide growth rate for the ultra-thin layers may be dependent on the specific microstructure. In-situ XPS performed on homogenous samples confirmed the interpretation of the optical experiments, and additionally, allowed the progressive oxidation of the underlying Co to be observed. Tunnel barriers formed utilizing optical data as well as the in situ XPS data yielded tunneling magnetoresistance (TMR) ratios (ΔR/Rp) of over 27% at 295K for Si(111)/Ta/Co/FeMn/Co/Al2O3/Co.