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

Document Type

Article

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.