Giant tunnel resistance effect in (SrTiO)/(BaTiO)/(CaTiO) asymmetric superlattice with enhanced polarization

In this work, we report the effectively enhanced tunneling electroresistance effect in Au/(SrTiO 3 ) 2 /(BaTiO 3 ) 4 /(CaTiO 3 ) 2 /Nb:SrTiO 3 superlattice ferroelectric tunnel junction (FTJ). The stable polarization switching and enhanced ferroelectricity were achieved in the nanoscale thickness high-quality epitaxial superlattice. A high ON/OFF current ratio of more than 10 5 was obtained at room temperature, which is an order of magnitude larger than the BaTiO 3 FTJ with the same structure. Nonvolatile resistance switching controlled by nonvolatile polarization switching was observed in the superlattice FTJ. Driven by increased polarization and intrinsic asymmetric ferroelectricity, a highly asymmetric depolarization field is generated compared with the Au/BaTiO 3 /Nb:SrTiO 3 FTJ, resulting in an enhanced tunneling electroresistance effect. These results provide a potential way to construct FTJ memory devices by constructing asymmetric three-component ferroelectric superlattices. By constructing a superlattice with an asymmetric structure of (SrTiO 3 ) 2 /(BaTiO 3 ) 4 /(CaTiO 3 ) 2 , polarization enhancement is achieved, thereby leading to an improvement in the ON/OFF ratio.