Yang Shuli, Kang Lili, Zheng Xiaohong, Jiang Peng, Zhao Gaofeng
Institute for Computational Materials Science, School of Physics and Electronics, International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, Henan University, Kaifeng 475004, China.
College of Information Science and Technology, Nanjing Forestry University, Nanjing 210037, China.
J Chem Phys. 2023 Oct 7;159(13). doi: 10.1063/5.0166849.
Two-dimensional (2D) ferroelectric tunnel junctions (FTJs) have great potential in the design of non-volatile memory devices due to the tunneling electroresistance (TER) effect and the fact that it is not constrained by critical thickness. Incorporation of 2D ferroelectric materials in realistic FTJs inevitably involves the contacts to the traditional three-dimensional (3D) metals. However, how to design the FTJs by combining the 2D ferroelectric materials with the 3D metals still needs to be studied. In this work, we design a vertical 3D FTJ by adopting the 3D metal Au as the left and right electrodes and the 2D ferroelectric material In2Se3 together with h-BN as the central scattering region. By density functional theory combined with the non-equilibrium Green's function (NEGF) method, we demonstrate that the h-BN intercalation with a large bandgap plays the role of good "insulator," which breaks the symmetry of the left and right electrodes. As a result, we obtain the TER ratio of about 170%, and it can be further improved to about 1200% if two layers of In2Se3 (2L-In2Se3) are adopted as the tunneling barrier layer. Our results provide another way for the design and application of ferroelectric memory devices based on 2D ferroelectric materials.
二维（2D）铁电隧道结（FTJ）由于隧穿电阻（TER）效应以及不受临界厚度限制这一事实，在非易失性存储器件设计中具有巨大潜力。在实际的FTJ中引入二维铁电材料不可避免地涉及到与传统三维（3D）金属的接触。然而，如何将二维铁电材料与三维金属相结合来设计FTJ仍有待研究。在这项工作中，我们设计了一种垂直三维FTJ，采用三维金属金作为左右电极，二维铁电材料In2Se3与h - BN作为中心散射区域。通过密度泛函理论结合非平衡格林函数（NEGF）方法，我们证明具有大能隙的h - BN插层起到了良好的“绝缘体”作用，打破了左右电极的对称性。结果，我们获得了约170%的TER比率，如果采用两层In2Se3（2L - In2Se3）作为隧穿势垒层，TER比率可进一步提高到约1200%。我们的结果为基于二维铁电材料的铁电存储器件的设计和应用提供了另一种途径。
