Berlin 2012 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 37: Poster II: Focused electron beam induced processing for the fabrication of nanostructures (focused session, jointly with O); Nanoengineered thin films; Layer properties: electrical, optical, and mechanical properties; Thin film characterization: structure analysis and composition (XRD, TEM, XPS, SIMS, RBS,..); Application of thin films
DS 37.32: Poster
Donnerstag, 29. März 2012, 15:00–17:00, Poster E
Texture analysis of MgO layers in MgO-CoFeB thin film systems by HRTEM — •Patrick Peretzki1, Vladyslav Zbarsky2, Marvin Walter2, Henning Schuhmann1, Filip Podjaski1, Markus Münzenberg2, and Michael Seibt1 — 1IV. Physikalisches Institut, Georg-August-Universität Göttingen — 2I. Physikalisches Institut, Georg-August-Universität Göttingen
Magnetic tunnel junctions (MTJs) consisting of two ferromagnetic amorphous CoFeB electrodes separated by a crystalline MgO tunnel barrier are good and well-studied candidates for industrial use of the tunnel magnetoresistance (TMR) effect for a variety of applications. Practical use requires a clearly defined nanostructure of the MgO barrier which is only a few monolayers thick and tends to crystallize in a textured grain structure. However, the exact influence of the degree of texturing on the MTJ behaviour, for example the TMR value or the mechanism of dielectric breakdown, is not clear. To clarify this, first steps were taken in developing a quantitative assessment of the MgO degree of texturing in several layer stacks with varying deposition temperature, layer order and thicknesses. Two approaches have been implemented and evaluated to quantitatively analyse the MgO layer texture from High Resolution Transmission Electron Microscopy (HRTEM) images obtained from the layer stacks. They use Fourier transform and Hough transform of the images, respectively. Results indicate a cumulative roughness effect in the stacks with layers having high degrees of texturing. We thank the DFG for funding through SFB 602.