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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
Author(s) -
Park SungMin,
Chung HaChang,
Lee SeongRae
Publication year - 2007
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200777408
Subject(s) - equiaxed crystals , microstructure , materials science , oxide , annealing (glass) , magnetoresistance , barrier layer , tunnel magnetoresistance , grain size , metallurgy , doping , composite material , layer (electronics) , optoelectronics , magnetic field , physics , quantum mechanics
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)