Stress-Induced Leakage Current in Magnetic Tunnel Junctions with Thin AlOx Barrier

Abstract

The degradation of magnetic tunnel junctions (MTJs) with AlOx barrier was experimentally investigated. Constant voltage stress was applied to MTJs, and time evolution of the conductance and the tunneling magnetoresistance (TMR) ratio were monitored. The gradual increase of the stress-induced leakage current (SILC) was observed prior to the breakdown following a power law function of the stress time, which is similar to the case of the ultrathin gate oxide films in Si-MOSFETs. The measured results suggest that the spin-dependent SILC component is involved in the early stage of the stress. Then, the spin-independent conduction becomes dominant as the degradation progresses, resulting in a reduction of TMR ratio.

Time Evolution of Resistance Drift of Magnetic Tunnel Junctions with Ultrathin AlOx Films

“…The tunnel barrier with a thickness of ~1 nm was formed by exposing a predeposited Al metal layer to oxygen plasma. CVS was applied to the MTJs and the current increase ∆I was monitored with stress time t. The time evolution of ∆I was found to be well fitted by a power law function [5]:…”