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

Abstract

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 (15-20 angstrom) 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. (C) 2005 American Institute of Physics.