Effect of Nb concentration on the microstructure of Al and the magneto resistive properties of the magnetic tunnel junction with a Nb-doped Al-oxide barrier

Sung Min Park, Ha Chang Chung, Seong Rae Lee

Research output: Contribution to journalArticle


We have investigated the composition dependence of magnetic tunnel junctions (MTJs) with Nb-alloyed Al-oxide (NbAlO x) and analyzed the microstructure changes and electrical property of Nb alloyed Al-oxide layer. After annealing, tunnel magnetoresistance (TMR) ratio of MTJ with Nb-alloyed Al-oxide barrier increased up to 38.5 % at 9.26 at. % Nb. As the Nb concentration increases, the grain size decreases and the microstructure becomes a dense, fine equiaxed-type structure with fine, continuous selected area diffraction (SAD) patterns, until Nb concentration reaches 9 at. %. The microstructural changes of Nb-alloyed Al layer results in smooth interface roughness, so that we could achieve a high TMR ratio. Resistance decreased from 900 Ω to 220 Ω and barrier height decreased from 1.62 eV to 0.847 eV at 9.26 at. % Nb. We speculated that the reduction of junction resistance of the MTJ with Nb-doped Al-oxide barrier was due to Nb d states formation in the band gap.

Original languageEnglish
Pages (from-to)3938-3941
Number of pages4
JournalPhysica Status Solidi (A) Applications and Materials Science
Issue number12
Publication statusPublished - 2007 Dec 1


ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Surfaces, Coatings and Films

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