Evolution of barrier-resistance noise in CoFeB/MgO/CoFeB tunnel junctions during annealing

Ryan Stearrett, W. G. Wang, L. R. Shah, Aisha Gokce, J. Q. Xiao, E. R. Nowak

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

The low-frequency resistance noise in sputtered-deposited magnetic tunnel junctions with MgO barriers has been measured as a function of annealing time at different annealing temperatures. The noise has a 1/f spectrum and it is quantified by a Hooge-like parameter α given in units of μ m 2. Unannealed devices have the highest noise levels and their α parameters exhibit a pronounced dependence on the voltage bias across the junction. A significant increase in tunneling magnetoresistance (TMR) is observed for short annealing times (on the order of minutes) at high temperatures and it is correlated with a large reduction in noise and in its bias dependence. The maximum TMR and minimum noise levels are reached at a later time that depends on temperature, being shorter at higher annealing temperatures. Devices annealed at 380 and at 430 °C exhibit the same minimum noise levels, α≈2× 10-10 μ m2. The origin of the resistance noise, its annealing time evolution, and its bias dependence are discussed and they are attributed to vacancy defects in the MgO barriers.

Original languageEnglish (US)
Article number064502
JournalJournal of Applied Physics
Volume107
Issue number6
DOIs
StatePublished - Apr 14 2010
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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