Journal of Magnetics

The Korean Magnetics Society (한국자기학회)
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Effect of Thermal Treatment on AIOx/Co90Fe10 Interface of Magnetic Tunnel Junctions Prepared by Radical Oxidation

  • Lee, Don-Koun (Ceramic Engineering, Advanced Materials Engineering, Yonsei University) ;
  • In, Jang-Sik (Ceramic Engineering, Advanced Materials Engineering, Yonsei University) ;
  • Hong, Jong-Ill (Ceramic Engineering, Advanced Materials Engineering, Yonsei University)
  • Published : 2005.12.01
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Abstract

We confirmed that the improvement in properties of magnetic tunnel junctions prepared by radical oxidation after thermal treatment was mostly resulted from the redistribution of oxygen at the $AIOx/Co_{90}Fe_{10}$ interface. The as-deposited Al oxide barrier was oxygen-deficient but most of it re-oxidized into $Al_2O_3$, the thermodynamically stable stoichiometric phase, through thermal treatment. As a result, the effective barrier height was increased from 1.52 eV to 2.27 eV. On the other hand, the effective barrier width was decreased from 8.2 ${\AA}$ to 7.5 ${\AA}$. X-ray absorption spectra of Fe and Co clearly showed that the oxygen in the CoFe layer diffused back into the Al barrier and thereby enriched the barrier to close to a stoichiometirc $Al_2O_3$ phase. The oxygen bonded with Co and Fe diffused back by 6.8 ${\AA}$ and 4.5 ${\AA}$ after thermal treatment, respectively. Our results confirm that controlling the chemical structures of the interface is important to improve the properties of magnetic tunnel junctions.

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