Authors: Jürgen Thomas Rainer Reiche Hartmut Vinzelberg
Publish Date: 2004/04/14
Volume: 379, Issue: 4, Pages: 576-581
Abstract
The basic elements of tunnel magnetoresists are two magnetic layers separated by an insulating barrier layer The uniformity of this only 1–2 nm thick barrier layer up to dot edges and the chemical composition of the layers are properties important for the efficiency of tunnel magnetoresistance devices These keyproperties have been investigated by analytical TEM methods like high resolution TEM imaging and energyfiltered imaging With regard to the chemical composition the TEM results have been confirmed by XPS investigations The subsequent oxidation of the barrier is one of the most critical steps of the deposition procedure of the layer stacks An undersized oxygen dose leads to an incomplete oxidation of the barrier layer with uncontrollable tunnel behaviour An overdose of oxygen leads to oxygen diffusion in the layers beneath the barrier and uncontrollable magnetic hardness of the lower magnetic electrodeThe authors would like to thank A Schumann U Hartmann R Kaltofen C Krien I Mönch and S Sieber for producing and structuring of the TMR layer stacks and D Lohse for careful electron microscopic preparation This work was partially supported by the Deutsche Forschungsgemeinschaft DFG WE 1519/10
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