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Review
. 2016 Dec;11(1):371.
doi: 10.1186/s11671-016-1584-5. Epub 2016 Aug 22.

Electronic Structures of Silicene Nanoribbons: Two-Edge-Chemistry Modification and First-Principles Study

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Free PMC article
Review

Electronic Structures of Silicene Nanoribbons: Two-Edge-Chemistry Modification and First-Principles Study

Yin Yao et al. Nanoscale Res Lett. .
Free PMC article

Abstract

In this paper, we investigate the structural and electronic properties of zigzag silicene nanoribbons (ZSiNRs) with edge-chemistry modified by H, F, OH, and O, using the ab initio density functional theory method and local spin-density approximation. Three kinds of spin polarized configurations are considered: nonspin polarization (NM), ferromagnetic spin coupling for all electrons (FM), ferromagnetic ordering along each edge, and antiparallel spin orientation between the two edges (AFM). The H, F, and OH groups modified 8-ZSiNRs have the AFM ground state. The directly edge oxidized (O1) ZSiNRs yield the same energy and band structure for NM, FM, and AFM configurations, owning to the same s p (2) hybridization. And replacing the Si atoms on the two edges with O atoms (O2) yields FM ground state. The edge-chemistry-modified ZSiNRs all exhibit metallic band structures. And the modifications introduce special edge state strongly localized at the Si atoms in the edge, except for the O1 form. The modification of the zigzag edges of silicene nanoribbons is a key issue to apply the silicene into the field effect transistors (FETs) and gives more necessity to better understand the experimental findings.

Keywords: Density functional theory; Electronic structure; Localized edge states; Silicene.

Figures

Fig. 1
Fig. 1
Structures. The top and side views of the no spin polarization (NM) ZSiNRs with edge-chemistry modification by a H, b F, c OH, d O1: direct oxidation, and e O2: replacing two-edge Si atoms with O atoms. Some notable bond length (in angstroms) and angles (in degrees) are marked in the figure to describe the structure change of ZSiNRs with these modification. The blue dots represent the H atoms, the green dots represent the F atoms, the red dots represent the O atoms, and the black dots represent the Si atoms
Fig. 2
Fig. 2
H. The band structures with the two-edge-chemistry modified by hydrogen for three kinds of spin configuration: a no spin polarization (NM), b ferromagnetic spin coupling for all electrons (FM), and c ferromagnetic ordering along each edge and antiparallel spin orientation between the two edges (AFM). d Band-decomposed charge densities of the edge states are also given (the isosurface is set to 0.0027a03)(a 0: Bohr radius). For the FM and AFM, spin-up and spin-down states are represented by the black and red lines in the band structure. The projected density of states (pDOS) of the Si atoms at the edge are shown in e
Fig. 3
Fig. 3
F. The band structures with the two-edge-chemistry modified by fluorine for three kinds of spin configuration: a no spin polarization (NM), b ferromagnetic spin coupling for all electrons (FM), and c ferromagnetic ordering along each edge and antiparallel spin orientation between the two edges (AFM). d Band-decomposed charge densities of the edge states are also given (the isosurface is set to 0.0027a03)(a 0: Bohr radius). For the FM and AFM, spin-up and spin-down states are represented by the black and red lines in the band structure. The projected density of states (pDOS) of the Si atoms at the edge are shown in e
Fig. 4
Fig. 4
OH. The band structures with the two-edge-chemistry modified by hydroxyl for three kinds of spin configuration: a no spin polarization (NM), b ferromagnetic spin coupling for all electrons (FM), and c ferromagnetic ordering along each edge and antiparallel spin orientation between the two edges (AFM). d Band-decomposed charge densities of the edge states are also given (the isosurface is set to 0.0027a03)(a 0: Bohr radius). For the FM and AFM, spin-up and spin-down states are represented by the black and red lines in the band structure. The projected density of states (pDOS) of the Si atoms at the edge are shown in e
Fig. 5
Fig. 5
O1. a The non-spin-polarized band structures with the two-edge-chemistry modified by oxidation directly (O1: Si–O), which is almost the same with that of FM and AFM configurations. b Band-decomposed charge densities of the edge states (the isosurface is set to 0.0027a03)(a 0: Bohr radius)
Fig. 6
Fig. 6
O2. The band structures with the two-edge-chemistry modified by the oxygen atoms replaced the Si atoms (O2: Si–O–Si) for three kinds of spin configuration: a no spin polarization (NM), b ferromagnetic spin coupling for all electrons (FM), and c ferromagnetic ordering along each edge and antiparallel spin orientation between the two edges (AFM). d Band-decomposed charge densities of the edge states are also given (the isosurface is set to 0.0027a03)(a 0: Bohr radius). For the FM and AFM, spin-up and spin-down states are represented by the black and red lines in the band structure. The projected density of states (pDOS) of the Si atoms at the edge are shown in e

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