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

✍ Scribed by Park, Sung-Min ;Chung, Ha-Chang ;Lee, Seong-Rae

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 259 KB
• Volume: 204
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/pssa.200777408

✦ Synopsis

Abstract

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. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)