報告題目：Anisotropic behavior in phosphorene and vdWs 2D topological insulators
主 講 人：寇良志Liangzhi Kou*
School of Chemistry, Physics and Mechanical Engineering,
Queensland University of Technology, Brisbane, Australia.
報告時間：2016年6月3日15：00
報告地點：化學樓二樓一號會議室
As the cousin of graphene, the new 2D material phosphorene has been exfoliated experimentally1. The unique anistropic properties originated from its puckered structure is distinguishing it from other 2D countpart2. From first principles calculations, we predicted the excellent gas sensor performance3, especially for N-based gas moleculars, like NO2, and anisotropic transport properties, which has been conformed from experiments. Meanwhile the unique direction selective out-plane deformation is also demonstrated, where ripple mainly occurs along zigzag direction, but not armchair direction. The electronic modulation is therefore direction selective4.
Although possessing these intriguing and unique properties, its practical application is obstructed by oxidation in the air2. Encapsulation technology is a possible solution, which can not only protect the vulnerable surface, but also enhance the spin orbit coupling (leading to QSH phase) due to the proximity effect when choose a suitable substrate. Take graphene as an example, we demonstrated from first principles calculations that, when sandwiched between two cladding layers, graphene can be turned into 2D topological insulators with nontrivial gap from 2-120 meV depending on the chosen substrate (Bi2Se3, MoTe2, or BiTeI)5-7. It provides a feasible approach to use graphene for innovative QSH device designs.
References
(1) L. Li, Y. Yu, G. J. Ye, Q. Ge, X. Ou, H. Wu, D. Feng, X. H. Chen, Y. Zhang, "Black Phosphorus Field-Effect Transistors, " Nat. Nanotechnol. 2014, 9, 372– 377.
(2) L. Kou, C. Chen, S. Smith, "Phosphorene: Fabrication, Properties, and Applications" J. Phys. Chem. Lett, 2015, 6, 2794-2805.
(3) L. Kou, T. Frauenheim, C. Chen, "Phosphorene as a Superior Gas Sensor: Selective Adsorption and Distinct IV Response" J. Phys. Chem. Lett, 2014, 5, 2675−2681.
(4) L. Kou, Y. Ma, C. Chen, S. Smith, "Anisotropic Ripple Deformation in Phosphorene” J. Phys. Chem. Lett, 2015, 6, 1509–1513.
(5) L. Kou, B. Yan, F. Hu, S. C. Wu, T. O. Wehling, C. Felser, C. Chen, T. Frauenheim, "Graphene-Based Topological Insulator with an Intrisinc Bulk Gap above Room Temperature" Nano Lett., 2013, 13, 6251-6255.
(6) L. Kou, F. Hu, B. Yan, T. O. Wehling, C. Felser, T. Frauenheim, C. Chen, "Proximity Enhanced Quantum Spin Hall State in Graphene" Carbon, 2015, 87, 418-423.
(7) L. Kou, S. C. Wu, C. Felser, T. Frauenheim, C. Chen, B. Yan, "Robust 2D Topological Insulators in van der Waals Heterostructures" ACS Nano, 2014, 8, 10448-10454.
