Reliability study of magnetic tunnel junction with naturally oxidized MgO barrier

We examined the breakdown characteristics of naturally oxidized MgO barriers using a time dependent dielectric breakdown (TDDB) technique. We found that the positive bias dependence of the breakdown time can be explained using the E-model and negative bias dependence can be explained using the power-law model. This asymmetric nature of the oxidized MgO barrier was due to unoxidized Mg metal at the reference/barrier interface. We also estimated the lifetime expansion under pulse voltage stress by taking the Joule heating effects into account.