Resonant band engineering of ferroelectric tunnel junctions

Authors

Jing Su, Shandong University
Xingwen Zheng, Shandong University
Zheng Wen, Qingdao University
Tao Li, Xi’an Jiaotong University
Shijie Xie, Shandong University
Karin M. Rabe, Rutgers University
Xiaohui Liu, Shandong University
Evgeny Y. Tsymbal, University of Nebraska at LincolnFollow

Date of this Version

8-2-2021

Citation

PHYSICAL REVIEW B 104, L060101 (2021). DOI: 10.1103/PhysRevB.104.L060101

Comments

Used by permission.

Abstract

We propose energy band engineering to enhance tunneling electroresistance (TER) in ferroelectric tunnel junctions (FTJs). We predict that an ultrathin dielectric layer with a smaller band gap, embedded into a ferroelectric barrier layer, acts as a switch controlling high- and low-conductance states of an FTJ depending on polarization orientation. Using first-principles modeling based on density functional theory, we investigate this phenomenon for a prototypical SrRuO₃/BaTiO₃/SrRuO₃ FTJ with a BaSnO₃ monolayer embedded in the BaTiO₃ barrier. We show that in such a composite-barrier FTJ, ferroelectric polarization of BaTiO₃ shifts the conduction-band minimum of the BaSnO₃ monolayer above or below the Fermi energy depending on polarization orientation. The resulting switching between direct and resonant tunneling leads to a TER effect with a giant ON/OFF conductance ratio. The proposed resonant band engineering of FTJs can serve as a viable tool to enhance their performance, useful for device applications.