Role of interface traps on breakdown process of a magnetic tunnel junction

Time dependent dielectric breakdown (TDDB) measurements were carried out for magnetic tunneling junctions (MTJs) with different electron trap densities at the interface between a bottom electrode and an insulating barrier. The TDDB shows a strong bias-polarity dependence, which becomes bigger with increasing trap density. In addition, the current creep before total dielectric breakdown consistently shows bias-polarity dependence. The polarity dependence of the breakdown in MTJs with an ultrathin tunneling barrier (15–20Å) is believed to be caused by precursor effect of the traps at the bottom interface, which enhances the trap generation rate in a tunneling barrier, resulting in acceleration of the breakdown process.