Effects of electrodes and space charges on the tunneling electroresistance in the ferroelectric tunnel junction with a SrTiO_3/BaTiO_3 composite barrier

摘要

Using the lattice model for strained nanoscale ferroelectric films and quantum tunneling theory, we present a theoretical investigation of tunneling electroresistance (TER) in the ferroelectric tunnel junction (FTJ) with a SrTiO_3/BaTiO_3 composite barrier. The exact profile of local polarizations within the composite barrier is calculated from first principles. It is found that the TER will sensitively depend on the choice of electrode with the increase in SrTiO_3 barrier's thickness. The space charges, which exist at the interface between the two barriers, will enhance the TER, and provide an effective approach to achieving large TER in FTJs.