Progress has been made in the construction of a single layer of graphene "protective layer" on the surface of silicone and its heterogeneity structure

Silicone is a honeycomb warp structure arranged by silicon atoms. Because of its geometric configuration similar to graphene, theoretical calculations have found that the energy belt structure of siliconene is similar to graphene, and dirac cones are also present at the top corner (K-point) of the Briyuan region, with the carrier being the massless Diracfemi. Since silicon atoms are heavier than carbon atoms, silicone has a stronger spin orbital coupling interaction, and the theory predicts that it is possible to observe the quantum spin Hall effect and the quantum abnormal Hall effect
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in silicone. Theoretical calculations have also found that the size of the energy gap at the Silicone Dirac point can be adjusted by means of the addition of electric field or alkali metal atom adsorption. However, silicone is highly susceptible to oxidation in the air due to its active chemical properties. L. Tao et al. successfully prepared silicone transistor devices for the first time in 2015 and measured the carrier migration rate of silicone, however, due to the instability of silicone in the air, the devices they prepared survived only two minutes. Nanotechnol., 2015, 10, 227. On the other hand, silicone-based heterogeneity structure is also theoretically predicted to have excellent physical and chemical properties, but because silicon does not exist in nature similar to graphite layer material, silicone can not be obtained through the traditional mechanical peeling method, and silicone-based heterogeneity structure system can not be prepared by the traditional "stacking" method. Therefore, how to prepare stable silicone and silicone-based two-dimensional heterogeneity structure is currently facing great challenges in experiments.
In recent years, the Institute of Physics of the Chinese Academy of Sciences/Beijing National Research Center for Condensed Physics Nanophysics and Devices Laboratory Gao Hongxuan team in graphene and graphene-like two-dimensional atomic crystal material preparation, material and application of the basis for research, and achieved a series of international cutting-edge research results. Over the past decade or so, they have used molecular beam extension growth methods, 1) to prepare large areas, high-quality graphene and graphene-like two-dimensional atomic crystal materials, such as: extended graphene (Chin. Phys. 16, 3151 (2007), Adv. Mater. 21, 2777 (2009) silene (Nano Lett. 13, 685 (2013), Nano Lett. 17, 1161 (2017)), niobium (Nano Lett. 13, 4671 (2013)), ene (Adv. Mater. 26, 4820 (2014), platinum dioxide and copper selenium 2D atomic crystals (Nano Lett. 15, 4013 (2015), Nat. Mater., 16, 717 (2017), etc.;2) enables the insertion of a variety of monomer elements of graphene . . . Phys. Lett. 100, 093101 (2012), Appl. Phys. Lett. 99, 163107 (2011);3) reveals the universal mechanism of graphene inserts on a single crystal surface. Chem. Soc. 137 (22), 7099 (2015), etc. This series of work has laid the foundation for exploring new two-dimensional materials and constructing heterogeneic structures of two-dimensional materials.Recently, the research team's Li Jing, Zhang Lizhi (co-first author) and Du Shixuan (co-communications author) combined STM experiments with theoretical calculations to make new progress in the study of silicone and its heterogeneous structure, which is "protected" by single-layer graphene. They first grew a layer of graphene on the Ru (0001) substrate and inserted silicon atoms under it to build it. At the same time, by controlling the amount of silicon, they prepared different types of silicon nanostructures under graphene and analyzed them by scanning tunnel microscopes (STM) imaging. At low doses, the periodic arrangement of silicene nano-fragment arrays at the top (atop) of the graphene molar pattern is a new type of patterned two-dimensional material, while at higher doses, the inserted Si forms a single layer of silicone. At higher Si doses, polysilene is formed between graphene and the substrate. This series of processes is confirmed by the calculation of the principle of first nature. The prepared graphene/silicon heterogenetic structure was exposed to air for two weeks without showing observable damage, indicating good air stability. The vertical transport characteristics of heterogeneity structure show the rectation effect.
related work is published in Advanced Materials. The work was supported by the Ministry of Science and Technology (2013CBA01600, 2016YFA020230, 2018 FYA0305800), the National Natural Science Foundation of China (61390501, 61474141, 11604373) and the Chinese Academy of Sciences.
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diagram 1. Schematic of the siene structure at the graphene/Ru (0001) interface. During the de-ignition process, the deposited Si atoms are inserted between graphene and the Ru substrate. When the deposits are small, Si atoms form honeycomb-shaped silicene nano flakes under the graphene molar map top region (the bulging region). With the increase of Si deposition, the laminated structure forms a single layer structure of silicone.
2. STM images and theoretical simulations of silicon nano-sheet arrays. (a) The STM shape shows the graphene/Ru (0001) structure behind the Si interpolation. The illustration is an enlarged image of (a). (b,c) Atomic-grade resolution images of silicone and graphene obtained in the same area at -0.5 V and -0.1 V bias, respectively. (d) A model of the atomic structure of a silicon sheet consisting of 26 Si atoms inserted under the graphene molar lattic top region. (e,f) the models in (d) calculated the simulated STM images using the principle of first nature at -0.5 eV and -0.1 eV, respectively, consistent with the experimental observations.
3. STM images and theoretical simulations of single-layer silicone. (a) STM images of graphene/silicon heterogenetic structures growing on the surface of Ru (0001). (b) Atomic resolution image of the surface graphene lattic. (c) (7×7) Ru (0001)/(√21×√21) silene/(8×8) top and side views of the graphene heterogeneity structure model (ultra-lattic cells are marked by red diamonds). (d) (c) The first nature principle of medium configuration simulates the STM image.
4. Electronic Local Area Function (ELF) calculation and transport characteristics of graphene/silicon heterogeneity structures. (a,b) An electron local area function (ELF) distribution map of silicon nanotubes and single-layer silicone in the silicon atomic plane. c) The current-voltage curve of the vertical heterogeneic structure of graphene/silicone/radon measured at 105 K, showing that the typical Schott-based type is popular. Illustrations are diagrams of device structures and measurements. d) A detentat of the V.A. curve. The ideal factor obtained by fitting it to the Schockley model is 1.5.