Degradation and breakdown of plasma oxidized magnetic tunnel junctions:: Single trap creation in Al2O3 tunnel barriers

We present an in-depth analysis of the reliability of plasma oxidized magnetic tunnel junctions, using constant voltage stress until breakdown. In the stress measurements, prebreakdown current jumps were also observed. We show that the prebreakdown jumps, as well as the final breakdown are caused by the generation of single trap conduction paths in the barrier. Finally, we demonstrate that applying stress can also cause gradual resistance changes, which can either be reversible or irreversible.