First-Principles Calculation on Geometric, Electronic and Optical Properties of Fully Fluorinated Stanene: a Large-Gap Quantum Spin Hall Insulator
Hong Wu1, Feng Li2**
1Department of Physics, Nanjing University of Posts and Telecommunications, Nanjing 210023 2College of Chemistry and Materials Science, Jiangsu Key Laboratory of Biofunctional Materials, Nanjing Normal University, Nanjing 210023
Abstract:The searches for large-gap quantum spin Hall insulators are important for both practical and fundamental interests. In this work, we present a theoretical observation of the two-dimensional fully fluorinated stanene (SnF) by means of density functional theory. Remarkably, a significant spin-orbit coupling is observed for the SnF monolayer in the valence band at the ${\it \Gamma}$ point, with a considerable indirect band gap of 278 meV. The direct gap of the SnF monolayer is at the ${\it \Gamma}$ point, which is slightly larger by as much as 381 meV. In addition, the elastic modulus of the SnF monolayer is about 20 J/m$^{2}$, which is comparable with the in-plane stiffness of black phosphorus monolayer along the $x$-direction ($\sim$28.94 J/m$^{2})$. Finally, the optical properties of stanene, SnF monolayer and stanene/SnF bilayer are calculated, in which the stanene/SnF bilayer is supposed to be an attractive sunlight absorber.
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