Ferroelectric Tunnel Junctions Enhanced by a Polar Oxide Barrier Layer

• DOI: 10.1021/acs.nanolett.9b03056
• Publication Date: 2019-09-13T08:03:55Z
• Authors: Qiong Yang; Lingling Tao; Yuke Zhang; Ming Li; Zhen Jiang; Evgeny Y. Tsymbal; Vitaly Alexandrov
• Keywords: Barrier layer; Tunnel junction

Ferroelectric tunnel junctions (FTJs) have recently aroused significant interest due to the interesting physics controlling their properties and potential application in nonvolatile memory devices. In this work, we propose a new concept design high-performance FTJs based on ferroelectric/polar-oxide composite barriers. Using density functional theory calculations, model electronic transport of LaNiO3/PbTiO3/LaAlO3/LaNiO3 demonstrate that an ultrathin polar LaAlO3(001) layer strongly enhances performance. We predict tunneling electroresistance (TER) effect these with OFF/ON resistance ratio exceeding factor 104 ON state as low about 1 kΩμm2. Such enhanced performance is driven by ionic charge at PbTiO3/LaAlO3 interface, which significantly increases transmission across FTJ when ferroelectric polarization PbTiO3 pointing against intrinsic electric field produced charge. This formation two-dimensional (2D) electron or hole gas, depending LaAlO3 termination being (LaO)+ (AlO2)-, respectively, formed screen nonuniform state. 2D (hole) gas can be switched OFF reversal polarization, resulting giant TER effect. The proposed suggests direction for creating stable reversible sizable effect, low-resistance-area product, required applications.